Trecora Resources (TREC) 10-K 15 Mar 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Mar. 04, 2019	Jun. 30, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	TRECORA RESOURCES
Entity Central Index Key	0000007039
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Public Float			$ 254
Entity Common Stock, Shares Outstanding		24,686,830
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Document Type	10-K
Amendment Flag	false
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Document Period End Date	Dec. 31, 2018

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
CURRENT ASSETS
Cash and cash equivalents	$ 6,735	$ 3,028
Trade receivables, net (Note 5)	27,112	25,779
Inventories (Note 7)	16,539	18,450
Prepaid expenses and other assets (Note 6)	4,664	3,645
Taxes receivable	182	5,584
Total current assets	55,232	56,486
PLANT, PIPELINE, AND EQUIPMENT – AT COST	268,419	245,761
LESS ACCUMULATED DEPRECIATION	(73,762)	(63,240)
PLANT, PIPELINE, AND EQUIPMENT, NET	194,657	182,521
GOODWILL (Note 9)	21,798	21,798
OTHER INTANGIBLE ASSETS, net (Note 9)	18,947	20,808
INVESTMENT IN AMAK (Note 10)	38,746	45,125
MINERAL PROPERTIES IN THE UNITED STATES (Note 11)	588	588
TOTAL ASSETS	329,968	327,326
CURRENT LIABILITIES
Accounts payable	19,106	18,347
Accrued liabilities (Note 13)	5,439	3,961
Current portion of post-retirement benefit (Note 22)	19	305
Current portion of long-term debt (Note 12)	4,194	8,061
Current portion of other liabilities	733	870
Total current liabilities	29,491	31,544
LONG-TERM DEBT, net of current portion (Note 12)	98,288	91,021
POST- RETIREMENT BENEFIT, net of current portion (Note 22)	358	897
OTHER LIABILITIES , net of current portion	994	1,611
DEFERRED INCOME TAXES (Note 16)	15,676	17,242
Total liabilities	144,807	142,315
COMMITMENTS AND CONTINGENCIES (Note 14)
EQUITY
Common Stock ‑ authorized 40 million shares of $.10 par value; issued 24.6 and 24.5 million in 2018 and 2017, respectively, and outstanding 24.5 and 24.3 million in 2018 and 2017, respectively	2,463	2,451
Additional Paid-in Capital	58,294	56,012
Common Stock in Treasury, at cost 0.1 million and 0.2 million shares in 2018 and 2017, respectively	(8)	(196)
Retained Earnings	124,123	126,455
Total Trecora Resources Stockholders' Equity	184,872	184,722
Noncontrolling interest	289	289
Total equity	185,161	185,011
TOTAL LIABILITIES AND EQUITY	$ 329,968	$ 327,326

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Common stock, shares authorized (in shares)	40,000,000	40,000,000
Common stock, par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, shares issued (in shares)	24,600,000	24,500,000
Common stock, shares outstanding (in shares)	24,500,000	24,300,000
Treasury stock (in shares)	100,000	200,000

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues
Revenues	$ 287,932	$ 245,143	$ 212,399
Operating costs and expenses
Cost of specialty petrochemical, product sales, and processing (including depreciation and amortization of $13,618, $10,089, and $9,016, respectively)	260,114	203,582	172,497
Gross Profit	27,818	41,561	39,902
General and Administrative Expenses
General and administrative	22,396	22,587	20,434
Restructuring and severance (Note 21)	2,347	0	0
Depreciation	740	872	761
Total General and Administrative Expenses	25,483	23,459	21,195
Operating income (loss)	2,335	18,102	18,707
Other income (expense)
Interest expense	(4,100)	(2,931)	(1,985)
Loss on extinguishment of debt	(315)	0	0
Bargain purchase gain from acquisition (Note 3)	0	0	11,549
Equity in losses of AMAK (Note 10)	(901)	(4,261)	(1,479)
Gain from additional equity issuance by AMAK (Note 10)	0	0	3,168
Miscellaneous expense	(158)	(60)	(28)
Total other income (expense)	(5,474)	(7,252)	11,225
Income (loss) before income tax expense	(3,139)	10,850	29,932
Income tax benefit (expense)	807	7,159	(10,504)
Net income (loss) attributable to Trecora Resources	$ (2,332)	$ 18,009	$ 19,428
Net income (loss) per common share
Basic earnings (loss) per share (in dollars per share)	$ (0.10)	$ 0.74	$ 0.80
Diluted earnings (loss) per share (in dollars per share)	$ (0.10)	$ 0.72	$ 0.78
Weighted average number of common shares outstanding
Basic (in shares)	24,438	24,294	24,284
Diluted (in shares)	24,438	25,129	24,982
Specialty petrochemical and product sales
Revenues
Revenues	$ 269,780	$ 227,334	$ 193,581
Processing fees
Revenues
Revenues	$ 18,152	$ 17,809	$ 18,818

CONSOLIDATED STATEMENTS OF OP_2

CONSOLIDATED STATEMENTS OF OPERATIONS (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Costs and Expenses [Abstract]
Depreciation and amortization included in the cost of specialty petrochemical, product sales, and processing	$ 13,618	$ 10,089	$ 9,016

CONSOLIDATED STATEMENT OF STOCK

CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Treasury Stock	Retained Earnings	Trecora Resources	Noncontrolling Interest
Balance (in shares) at Dec. 31, 2015		24,158,000
Balance at Dec. 31, 2015	$ 142,385	$ 2,416	$ 50,662	$ 0	$ 89,018	$ 142,096	$ 289
Stock options
Issued to Directors	173		173			173
Issued to Employees	1,234		1,234			1,234
Issued to Former Director	48		48			48
Restricted common stock
Issued to Directors	254		254			254
Issued to Employees	783		783			783
Common stock
Issued to Directors (in shares)		13,000
Issued to Directors	60	$ 2	58			60
Issued to Employees (in shares)		51,000
Issued to Employees	11	$ 3	(8)	16		11
Stock Exchange (see Notes 10 & 18)	0
Treasury stock transferred from TOCCO to TREC	0	$ 30	270	(300)
Net Income (Loss)	19,428				19,428	19,428
Balance (in shares) at Dec. 31, 2016		24,222,000
Balance at Dec. 31, 2016	164,376	$ 2,451	53,474	(284)	108,446	164,087	289
Stock options
Issued to Directors	100		100			100
Issued to Employees	1,171		1,171			1,171
Restricted common stock
Issued to Directors	310		310			310
Issued to Employees	1,136		1,136			1,136
Common stock
Issued to Directors (in shares)		29,000
Issued to Directors	(55)		(84)	29		(55)
Issued to Employees (in shares)		57,000
Issued to Employees	(36)		(92)	56		(36)
Stock Exchange (see Notes 10 & 18)	0
Warrants exercised (in shares)		3,000
Warrants exercised	0		(3)	3
Net Income (Loss)	$ 18,009				18,009	18,009
Balance (in shares) at Dec. 31, 2017	24,300,000	24,311,000
Balance at Dec. 31, 2017	$ 185,011	$ 2,451	56,012	(196)	126,455	184,722	289
Stock options
Issued to Directors	(10)		(10)			(10)
Issued to Employees	154		154			154
Cancellations (see Note 15)	(680)		(680)			(680)
Restricted common stock
Issued to Directors	338		338			338
Issued to Employees	1,939		1,939			1,939
Common stock
Issued to Directors (in shares)		188,000
Issued to Directors	588	$ 10	489	89		588
Issued to Employees (in shares)		183,000
Issued to Employees	284	$ 2	127	$ 155		284
Stock Exchange (see Notes 10 & 18) (in shares)		(65,000)		(65,000)
Stock Exchange (see Notes 10 & 18)	(131)		(66)	$ (65)		(131)
Warrants exercised (in shares)		9,000
Warrants exercised	0		(9)	9
Net Income (Loss)	$ (2,332)				(2,332)	(2,332)
Balance (in shares) at Dec. 31, 2018	24,500,000	24,626,000
Balance at Dec. 31, 2018	$ 185,161	$ 2,463	$ 58,294	$ (8)	$ 124,123	$ 184,872	$ 289

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net income (loss) attributable to Trecora Resources	$ (2,332)	$ 18,009	$ 19,428
Adjustments to reconcile net income (loss) attributable to Trecora Resources to net cash provided by operating activities:
Depreciation	12,497	9,100	7,896
Amortization of intangible assets	1,861	1,861	1,880
Unrealized gain on derivative instruments	0	(58)	(119)
Share-based compensation	1,753	2,707	2,552
Deferred income taxes	(1,566)	(5,841)	8,697
Postretirement obligation	(825)	(11)	271
Bargain purchase gain from acquisition	0	0	(11,549)
Equity in loss of AMAK	901	4,261	1,479
Gain from additional equity issuance by AMAK	0	0	(3,168)
Bad debt expense	152	0	90
Amortization of loan fees	261	247	272
Loss on extinguishment of debt	315	0	0
Changes in operating assets and liabilities:
Increase in trade receivables	(1,485)	(3,586)	(2,809)
(Increase) decrease in taxes receivable	5,401	(1,601)	3,689
(Increase) decrease in inventories	1,911	(579)	(2,067)
Increase in prepaid expenses and other assets	(1,222)	(806)	(1,022)
Increase (decrease) in other liabilities	33	142	(174)
Increase in accounts payable and accrued liabilities	2,240	6,983	3,168
Net cash provided by operating activities	19,895	30,828	28,514
Investing activities
Additions to plant, pipeline and equipment	(25,285)	(51,584)	(38,484)
Acquisition of B Plant	0	0	(2,011)
Proceeds from AMAK share repurchase (Note 10)	5,347	0	0
Advances to AMAK, net	67	(107)	(14)
Net cash used in investing activities	(19,871)	(51,691)	(40,509)
Financing Activities
Issuance of common stock	0	25	11
Net cash received (paid) related to stock-based compensation	860	(106)	0
Additions to long-term debt	18,177	26,000	8,000
Repayment of long-term debt	(15,354)	(10,417)	(6,250)
Net cash provided by in financing activities	3,683	15,502	1,761
Net increase (decrease) in cash and cash equivalents	3,707	(5,361)	(10,234)
Cash and cash equivalents at beginning of year	3,028	8,389	18,623
Cash and cash equivalents at end of year	6,735	3,028	8,389
Supplemental disclosure of cash flow information:
Cash payments for interest	4,560	3,540	2,545
Cash payments (net of refunds) for taxes	(4,182)	92	(1,630)
Supplemental disclosure of non-cash items:
Capital Expansion amortized to depreciation expense	787	840	1,047
Estimated earnout liability (Note 3)	0	0	733
Stock exchange (Notes 10 & 18)	$ 131	$ 0	$ 0

BUSINESS AND OPERATIONS OF THE

BUSINESS AND OPERATIONS OF THE COMPANY	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
BUSINESS AND OPERATIONS OF THE COMPANY	BUSINESS AND OPERATIONS OF THE COMPANY Trecora Resources, formerly Arabian American Development Company, (the "Company") was organized as a Delaware corporation in 1967. The Company's principal business activities are the manufacturing of various specialty petrochemical products, specialty waxes and providing custom processing services. The Company owns 33% of a Saudi Arabian joint stock company, Al Masane Al Kobra Mining Company ("AMAK") (see Note 10) and approximately 55% of the capital stock of a Nevada mining company, Pioche Ely Valley Mines, Inc. ("PEVM"), which does not conduct any substantial business activity but owns undeveloped properties in the United States. The Company's specialty petrochemical operations are primarily conducted through a wholly-owned subsidiary, Texas Oil and Chemical Co. II, Inc. ("TOCCO"). TOCCO owns all of the capital stock of South Hampton Resources, Inc. ("SHR") and Trecora Chemical, Inc. ("TC"). SHR owns all of the capital stock of Gulf State Pipe Line Company, Inc. ("GSPL"). SHR owns and operates a specialty petrochemical product facility near Silsbee, Texas which manufactures high purity hydrocarbons used primarily in polyethylene, packaging, polypropylene, expandable polystyrene, poly-iso/urethane foams, Canadian tar sands, and in the catalyst support industry. TC owns and operates a facility located in Pasadena, Texas which manufactures specialty waxes and provides custom processing services. These specialty waxes are used in the production of coatings, hot melt adhesives and lubricants. GSPL owns and operates pipelines that connect the SHR facility to a natural gas line, to SHR's truck and rail loading terminal and to a major petroleum pipeline owned by an unaffiliated third party. We attribute revenues to countries based upon the origination of the transaction. All of our revenues for the years ended December 31, 2018 , 2017 , and 2016 , originated in the United States. In addition, all of our long-lived assets are in the United States. For convenience in this report, the terms "Company", "our", "us" or "we" may be used to refer to Trecora Resources and its subsidiaries.

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Principles of Consolidation – The consolidated financial statements include the balance sheets, statements of income, stockholders' equity, and cash flows of the Company, TOCCO, TC, SHR, GSPL and PEVM. Other entities which are not controlled but over which the Company has the ability to exercise significant influence such as AMAK, are accounted for using the equity method of accounting. All intercompany profits, transactions and balances have been eliminated. Cash, Cash Equivalents and Short-Term Investments – Our principal banking and short-term investing activities are with local and national financial institutions. Short-term investments with an original maturity of three months or less are classified as cash equivalents. Inventories – Finished products and feedstock are recorded at the lower of cost, determined on the first-in, first-out method (FIFO), or market for SHR. For TC, inventory is recorded at the lower of cost or market as follows: (1) raw material cost is calculated using the weighted-average cost method and (2) product inventory cost is calculated using the specific cost method. Trade Receivables and Allowance for Doubtful Accounts – We evaluate the collectability of our trade receivables and adequacy of the allowance for doubtful accounts based upon historical experience and any specific customer financial difficulties of which we become aware. For the year ended December 31, 2018, we increased the balance by $152,000 due to concerns regarding collectability for a specific customer. For the year ended December 31, 2017, the allowance balance was not increased. In 2016, we increased the balance by $90,000 due to an increase in sales in countries where there is a greater risk of default and limited recourse should this occur. We track customer balances and past due amounts to determine if customers may be having financial difficulties. This, along with historical experience and a working knowledge of each customer, helps determine accounts that should be written off. No amounts were written off in 2018 or 2017. During 2016 we wrote off one account for approximately $93,000 . Notes Receivable – We periodically make changes in or expand our custom processing units at the request of the customer. The cost to make these changes is shared by the customer. Upon completion of a project a non-interest note receivable is recorded with an imputed interest rate. There were no notes receivable outstanding as of December 31, 2018. The interest rate used on outstanding notes during December 31, 2018 and 2017 was 4% . The unearned interest was reflected as a discount against the note balance. The Company evaluates the collectability of notes based upon a working knowledge of the customer. The notes are receivable from custom processing customers with whom we maintain a close relationship. Thus, all amounts due under the notes receivable are considered collectible, and no allowance was recorded at December 31, 2018 and 2017 , respectively. Plant, Pipeline and Equipment – Plant, pipeline and equipment are stated at cost. Depreciation is provided over the estimated service lives using the straight-line method. Gains and losses from disposition are included in operations in the period incurred. Maintenance and repairs are expensed as incurred. Major renewals and improvements are capitalized. Interest costs incurred to finance expenditures during construction phase are capitalized as part of the historical cost of constructing the assets. Construction commences with the development of the design and ends when the assets are ready for use. Capitalized interest costs are included in plant, pipeline and equipment and are depreciated over the service life of the related assets. Labor costs incurred to self-construct assets are capitalized as part of the historical cost the assets. Construction commences with the development of the design and ends when the assets are ready for use. Capitalized labor costs are included in plant, pipeline and equipment and are depreciated over the service life of the related assets. Platinum catalyst is included in plant, pipeline and equipment at cost. Amortization of the catalyst is based upon cost less estimated salvage value of the catalyst using the straight line method over the estimated useful life (see Note 8). Goodwill and Other Intangible Assets – Goodwill represents the future economic benefits arising from other assets acquired in the acquisition of TC that are not individually identified and separately recognized. Goodwill and indefinite-lived intangible assets are tested for impairment at least annually; however, these tests are performed more frequently when events or changes in circumstances indicate that the asset may be impaired. Impairment exists when carrying value exceeds fair value. Estimates of fair value are based on appraisals, market prices for comparable assets, or internal estimates of future net cash flows. Definite-lived intangible assets consist of customer relationships, licenses, permits and developed technology that were acquired as part of the Acquisition of TC. The majority of these assets are being amortized using discounted estimated future cash flows over the term of the related agreements. Intangible assets associated with customer relationships are being amortized using the discounted estimated future cash flows method based upon assumed rates of annual customer attrition. We continually evaluate the reasonableness of the useful lives of these assets. Once these assets are fully amortized, they will be removed from the consolidated balance sheets. Business Combinations and Related Business Acquisition Costs – Assets and liabilities associated with business acquisitions are recorded at fair value using the acquisition method of accounting. We allocate the purchase price of acquisitions based upon the fair value of each component which may be derived from various observable and unobservable inputs and assumptions. We may use third-party valuation specialists to assist us in this allocation. Initial purchase price allocations are preliminary and subject to revision within the measurement period, not to exceed one year from the date of acquisition. The fair value of property, plant and equipment and intangible assets are based upon the discounted cash flow method that involves inputs that are not observable in the market (Level 3). Goodwill assigned represents the amount of consideration transferred in excess of the fair value assigned to identifiable assets acquired and liabilities assumed. Business acquisition costs are expensed as incurred and are reported as general and administrative expenses in the consolidated statements of income. We define these costs to include finder's fees, advisory, legal, accounting, valuation, and other professional consulting fees, as well as, travel associated with the evaluation and effort to acquire specific businesses. Investment in AMAK – We account for our investment in AMAK using the equity method of accounting under which we record in income our share of AMAK's income or loss for each period. The amount recorded is also adjusted to reflect the amortization of certain differences between the basis in our investment in AMAK and our share of the net assets of AMAK as reflected in AMAK's financial statements (see Note 10). Any proceeds received from or payments made to AMAK are recorded as decreases or increases in the balance of our investment. We assess our investment in AMAK for impairment when events are identified, or there are changes in circumstances that may have an adverse effect on the fair value of the investment. We consider recoverable ore reserves, changes in commodity prices, and the amount and timing of the cash flows to be generated by the production of those reserves, as well as, recent equity transactions within AMAK. Other Assets – Other assets include a license used in specialty petrochemical operations, spare parts inventory and certain specialty petrochemical assets. Beginning January 1, 2017, due to the expansion of our plant assets at SHR and TC, we began inventorying spare parts for the repair and maintenance of our plant, pipeline and equipment. Spare parts are accounted for on the first-in, first-out method (FIFO). Long-Lived Assets Impairment – Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable based on the undiscounted net cash flows to be generated from the asset's use. The amount of the impairment loss to be recorded is calculated by the excess of the asset's carrying value over its fair value. Fair value is generally determined using a discounted cash flow analysis although other factors including the state of the economy are considered. Revenue Recognition – The Company adopted Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("ASC") Topic 606 ("ASC 606"), Revenue from Contracts with Customers, and its amendments with a date of the initial application of January 1, 2018. As a result, the Company has changed its accounting policy for revenue recognition as detailed below. ASC 606 outlines a single comprehensive model for an entity to use in accounting for revenue arising from all contracts with customers, except where revenues are in scope of another accounting standard. ASC 606 superseded the revenue recognition requirements in ASC Topic 605, " Revenue Recognition", and most industry specific guidance. ASC Topic 606 sets forth a five-step model for determining when and how revenue is recognized. Under the model, an entity is required to recognize revenue to depict the transfer of goods or services to a customer at an amount reflecting the consideration it expects to receive in exchange for those goods and services. ASC 606 also requires certain additional revenue-related disclosures. The Company applied the modified retrospective approach under ASC 606 which allows for the cumulative effect of adopting the new guidance on the date of initial application. Use of the modified retrospective approach means the Company's comparative periods prior to initial application are not restated. The initial application was applied to all contracts at the date of the initial application. The Company has determined that the adjustments using the modified retrospective approach did not have a material impact on the date of the initial application along with the disclosure of the effect on prior periods. Accounting Policy Beginning on January 1, 2018, revenue is measured based on a consideration specified in a contract with a customer. The Company recognizes revenue when it satisfies a performance obligation by transferring control over a product or service to a customer. In evaluating when a customer has control of the asset we primarily consider whether the transfer of legal title and physical delivery has occurred, whether the customer has significant risks and rewards of ownership, and whether the customer has accepted delivery and a right to payment exists. Taxes assessed by a governmental authority that are both imposed on and concurrent with a specific revenue-producing transaction, that are collected by the Company from a customer, are excluded from revenue. Shipping and handling costs associated with outbound freight after control over a product has transferred to a customer are accounted for as a fulfillment cost and are included in cost of product sales and processing. The Company does not offer material rights of return or service-type warranties. For the year ended December 31, 2017 the Company recognized revenue according to FASB ASC Topic 605 ("ASC 605"), " Revenue Recognition" , when: (1) the customer accepted delivery of the product and title had been transferred or when the service was performed and the Company had no significant obligations remaining to be performed; (2) a final understanding as to specific nature and terms of the agreed upon transaction had occurred; (3) price was fixed and determinable; and (4) collection was assured. Product sales generally met these criteria, and revenue was recognized, when the product was delivered or title was transferred to the customer. Sales revenue was presented net of discounts, allowances, and sales taxes. Freight costs billed to customers were recorded as a component of revenue. Revenues received in advance of future sales of products or prior to the performance of services were presented as deferred revenues. Shipping and handling costs were classified as cost of product sales and processing and were expensed as incurred. Nature of goods and services The following is a description of principal activities – separated by reportable segments – from which the Company generates its revenue. For more detailed information about reportable segments, disaggregation of revenues, and contract balance disclosures, see Note 17. Specialty petrochemical segment The specialty petrochemical segment of the Company produces eight high purity hydrocarbons and other petroleum based products including isopentane, normal pentane, isohexane and hexane. These products are used in the production of polyethylene, packaging, polypropylene, expandable polystyrene, poly-iso/urethane foams, crude oil from the Canadian tar sands, and in the catalyst support industry. SHR's specialty petrochemical products are typically transported to customers by rail car, tank truck, iso-container and ship. Product Sales – The Company sells individual (distinct) products to its customers on a stand-alone basis (point-of-sale) without any further integration. There is no significant modification of any one or more products sold to fulfill another promised product or service within any of the Company's product sale transactions. The amount of consideration received for product sales is stated within the executed invoice with the customer. Payment is typically due and collected 30 to 60 days subsequent to point of sale. Processing Fees – The Company's services consist of processing customer supplied feedstocks into custom products including, if requested, services for forming, packaging, and arranging shipping. Pursuant to Tolling Agreements the customer retains title to the feedstocks and processed products. The performance obligation in each Tolling Agreement transaction is the processing of customer provided feedstocks into custom products and is satisfied over time. The amount of consideration received for product sales is stated within the executed invoice with the customer. Payment is typically due and collected within 30 days subsequent to point of sale. Specialty Wax segment The specialty wax segment of the Company manufactures and sells specialty polyethylene and poly alpha olefin waxes and also provides custom processing services for customers. Product Sales – The Company sells individual (distinct) products to its customers on a stand-alone basis (point-of-sale) without any further integration. There is no significant modification of any one or more products sold to fulfill another promised product or service within any of the Company's product sale transactions. The amount of consideration received for product sales is stated within the executed invoice with the customer. Payment is typically due and collected within 30 days subsequent to point of sale. Processing Fees – The Company's promised services consist of processing customer supplied feedstocks into custom products including, if requested, services for forming, packaging, and arranging shipping. Pursuant to Tolling Agreements and Purchase Order Arrangements, the customer typically retains title to the feedstocks and processed products. The performance obligation in each Tolling Agreement transaction and Purchase Order Arrangement is the processing of customer provided feedstocks into custom products and is satisfied over time. The amount of consideration received for product sales is stated within the executed invoice with the customer. Payment is typically due and collected within 30 days subsequent to point of sale. Shipping and Handling Costs – Shipping and handling costs are classified as cost of product sales and processing and are expensed as incurred. Retirement Plan – We offer employees the benefit of participating in a 401(k) plan. We match 100% up to 6% of pay with vesting occurring over 2 years. For years ended December 31, 2018 , 2017 , and 2016 , matching contributions of approximately $1,502,000 , $1,412,000 , and $1,195,000 , respectively were made on behalf of employees. Environmental Liabilities – Remediation costs are accrued based on estimates of known environmental remediation exposure. Ongoing environmental compliance costs, including maintenance and monitoring costs, are expensed as incurred. Other Liabilities – We periodically make changes in or expand our custom processing units at the request of the customer. The cost to make these changes is shared by the customer. Upon completion of a project a note receivable and a deferred liability are recorded to recover the project costs which are then capitalized. At times instead of a note receivable being established, the customer pays an upfront cost. The amortization of other liabilities is recorded as a reduction to depreciation expense over the life of the contract with the customer. As of December 31 of each year, depreciation expense was offset and reduced by approximately $0.8 million , $0.8 million , and $1.0 million , for 2018 , 2017 , and 2016 , respectively. Net Income Per Share – We compute basic income per common share based on the weighted-average number of common shares outstanding. Diluted income per common share is computed based on the weighted-average number of common shares outstanding plus the number of additional common shares that would have been outstanding if potential dilutive common shares, consisting of stock options, unvested restricted stock units, and shares which could be issued upon conversion of debt, had been issued (see Note 18). Foreign Currency – The functional currency for the Company and each of the Company's subsidiaries is the US dollar (USD). Transaction gains or losses as a result of transactions denominated and settled in currencies other than the USD are reflected in the statements of income as foreign exchange transaction gains or losses. We do not employ any practices to minimize foreign currency risks. The functional and reporting currency of AMAK is the Saudi Riyal (SR). In June 1986 the SR was officially pegged to the USD at a fixed exchange rate of 1 USD to 3.75 SR; therefore, we translate SR into our reporting currency of the USD for income statement and balance sheet purposes using the fixed exchange rate. As of December 31, 2018 , 2017 and 2016 , foreign currency translation adjustments were not significant. Management Estimates – The preparation of consolidated financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. Significant estimates include allowance for doubtful accounts receivable and inventory obsolescence; assessment of impairment of our long-lived assets, goodwill, intangible assets and investments, litigation liabilities, post-retirement benefit obligations, guarantee obligations, environmental liabilities, income taxes and deferred tax valuation allowances. Actual results could differ from these estimates. Share-Based Compensation – We recognize share-based compensation of stock options granted based upon the fair value of options on the grant date using the Black-Scholes pricing model (see Note 15). Share-based compensation expense recognized during the period is based on the fair value of the portion of share-based payments awards that is ultimately expected to vest. Share-based compensation expense recognized in the consolidated statements of operations for the years ended December 31, 2018 , 2017 , and 2016 includes compensation expense based on the estimated grant date fair value for awards that are ultimately expected to vest, and accordingly has been reduced for estimated forfeitures. Estimated forfeitures at the time of grant are revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. Guarantees – We may enter into agreements which contain features that meet the definition of a guarantee under FASB ASC 460 "Guarantees" (see Note 14). These arrangements create two types of obligations: a) We have a non-contingent and immediate obligation to stand ready to make payments if certain future triggering events occur. For certain guarantees, a liability is recognized for the stand ready obligation at the inception of the guarantee; and b) We have an obligation to make future payments if those certain future triggering events do occur. A liability for the payment under the guarantee is recognized when 1) it becomes probable that one or more future events will occur, triggering the requirement to make payments under the guarantee and 2) when the payment can be reasonably estimated. Fair Value – The carrying value of cash and cash equivalents, trade receivables, taxes receivable, accounts payable, accrued liabilities, and other liabilities approximate fair value due to the immediate or short-term maturity of these financial instruments. The fair value of variable rate long term debt and notes payable reflect recent market transactions and approximate carrying value. We used other observable inputs that would qualify as Level 2 inputs to make our assessment of the approximate fair value of our cash and cash equivalents, trade receivables, taxes receivable, accounts payable, accrued liabilities, other liabilities, notes payable and variable rate long term debt. The fair value of the derivative instruments are described below. We measure fair value by ASC Topic 820 Fair Value. ASC Topic 820 defines fair value, establishes a framework for measuring fair value, and expands disclosures about fair value measurements. ASC Topic 820 applies to reported balances that are required or permitted to be measured at fair value under existing accounting pronouncements; accordingly, the standard amends numerous accounting pronouncements but does not require any new fair value measurements of reported balances. ASC Topic 820 emphasizes that fair value, among other things, is based on exit price versus entry price, should include assumptions about risk such as nonperformance risk in liability fair values, and is a market-based measurement, not an entity-specific measurement. When considering the assumptions that market participants would use in pricing the asset or liability, ASC Topic 820 establishes a fair value hierarchy that distinguishes between market participant assumptions based on market data obtained from sources independent of the reporting entity (observable inputs that are classified within Levels 1 and 2 of the hierarchy) and the reporting entity's own assumptions about market participant assumptions (unobservable inputs classified within Level 3 of the hierarchy). The fair value hierarchy prioritizes inputs used to measure fair value into three broad levels. In instances where the determination of the fair value measurement is based on inputs from different levels of the fair value hierarchy, the level in the fair value hierarchy within which the entire fair value measurement falls is based on the lowest level input that is significant to the fair value measurement in its entirety. Our assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment and considers factors specific to the asset or liability. Derivatives – We record derivative instruments as either an asset or liability measured at fair value. Changes in the derivative instrument's fair value are recognized currently in earnings unless specific hedge accounting criteria are met. Special accounting for qualifying hedges allows a derivative instrument's gains and losses to offset related results on the hedged item in the income statement, to the extent effective, and requires that a company must formally document, designate and assess the effectiveness of transactions that receive hedge accounting. Income Taxes – Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. The Company maintains a valuation allowance for a deferred tax asset when it is deemed to be more likely than not that some or all of the deferred tax asset will not be realized. Our estimate of the potential outcome of any uncertain tax issues is subject to management's assessment of relevant risks, facts, and circumstances existing at that time. We use a more likely than not threshold for financial statement recognition and measurement of tax position taken or expected to be taken in a tax return. To the extent that our assessment of such tax position changes, the change in estimate is recorded in the period in which the determination is made. We report tax-related interest and penalties as a component of income tax expense. On December 22, 2017, Public Law No. 115-97 known as the Tax Cuts and Jobs Act (TCJA) was enacted. The TCJA included a number of changes to existing U.S. tax laws that impact the Company, most notably a reduction of the U.S. federal corporate income tax rate from a maximum of 35 percent to a flat 21 percent for tax years effective January 1, 2018. The TCJA also implemented a territorial tax system, provided for a one-time deemed repatriation tax on unrepatriated foreign earnings, eliminated the alternative minimum tax (AMT), made AMT credit carryforwards refundable, and permitted the acceleration of depreciation for certain assets placed into service after September 27, 2017. In addition the TJCA created prospective changes beginning in 2018, including repeal of the domestic manufacturing deduction, acceleration of tax revenue recognition, capitalization of research and development expenditures, additional limitations on executive compensation and limitations on the deductibility of interest. The Company has elected to recognize the income tax effects of the TCJA in its financial statements in accordance with Staff Accounting Bulletin 118 (SAB 118), which provides guidance for the application of ASC Topic 740 Income Taxes , in the reporting period in which the TCJA was signed into law. Under SAB 118 when a Company does not have the necessary information available, prepared, or analyzed (including computations) in reasonable detail to complete the accounting for certain income tax effects of the TCJA it will recognize provisional amounts if a reasonable estimate can be made. If a reasonable estimate cannot be made then no impact is recognized for the effect of the TCJA. SAB 118 permits an up to one year measurement period to finalize the measurement of the impact of the TCJA. Reclassifications – Certain reclassifications have been made to prior year balances to conform with the current year presentation. Subsequent Events – The Company has evaluated subsequent events through March 15, 2019 , the date that the consolidated financial statements were approved by management. New Accounting Pronouncements In May 2014 the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2014-9, Revenue from Contracts with Customers ("ASU 2014-9"). ASU 2014-9 supersedes the revenue recognition requirements of FASB Accounting Standards Codification ("ASC") Topic 605, Revenue Recognition and most industry-specific guidance throughout the Accounting Standards Codification, resulting in the creation of FASB ASC Topic 606, Revenue from Contracts with Customers . ASU 2014-9 requires entities to recognize revenue in a way that depicts the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled to in exchange for those goods or services. This ASU provides alternative methods of retrospective adoption and is effective for fiscal years, and interim periods within those years, beginning after December 15, 2017. The Company completed its assessment of the impact of the adoption of ASU 2014-9 across all revenue streams. This included reviewing current accounting policies and practices to identify potential differences that would result from applying the requirements under the new standard. We completed contract reviews and validated results of applying the new revenue guidance (Note 2). See Revenue Recognition policy note. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842). This update will increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. This update is effective for annual and interim reporting periods beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. In July 2018, the FASB issued ASU No. 2018-11, Targeted Improvements to ASC 842, Leases. ASU 2018-11 provided entities with an alternative modified transition method to elect not to recast the comparative periods presented when adopting ASC 842. The new standard provides a number of optional practical expedients in transition. The Company expects to elect: (1) the ‘package of practical expedients’, which permits it not to reassess under the new standard its prior conclusions about lease identification, lease classification, and initial direct costs and (2) the use-of-hindsight. In addition, the new standard provides practical expedients for an entity’s ongoing accounting that the Company anticipates making, such as the (1) the election for certain classes of underlying asset to not separate non-lease components from lease components and (2) the election for short-term lease recognition exemption for all leases that qualify. The Company will adopt ASU 842 as of January 1, 2019, using the alternative modified transition method. In preparation of adopting ASC 842, the Company is implementing additional internal controls to enable future preparation of financial information in accordance with ASC 842. The Company has also substantially completed its evaluation of the impact on the Company’s lease portfolio. The Company believes the largest impact will be on the consolidated balance sheets for the accounting of rail cars, equipment and office leases, which represents a majority of its operating leases it has entered into as a lessee. These leases will be recognized under the new standard as right of use assets (“ROU”) operating lease liabilities. The Company will also be required to provide expanded disclosures for its leasing arrangements. As of December 31, 2018, the Company had approximately $ 18.1 million of undiscounted future minimum operating lease commitments that are not recognized on its consolidated balance sheets as determined under the current standard. For a lessee, the results of operations are not expected to significantly change after adoption of the new standard. While substantially complete, the Company is still in the process of finalizing its evaluation of the effect of ASU 842 on the Company’s financial statements and disclosures, including the determination of the Company’s incremental borrowing rate for each of the operating leases to estimate the interest rate we would have to pay to borrow on a collateralized basis over a similar term for an amount equal to the lease payments. The Company will finalize its accounting assessment and quantitative impact of the adoption during the first quarter of fiscal year 2019. In January 2017 the FASB issued ASU No. 2017-4, Intangibles – Goodwill and Other (Topic 350) . The amendments in ASU 2017-4 simplify the measurement of goodwill

ACQUISITION OF B PLANT

ACQUISITION OF B PLANT	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
ACQUISITION OF B PLANT	ACQUISITION OF B PLANT On May 2, 2016, we purchased the idle BASF facility adjacent to our TC facility in exchange for $2.0 million in cash, transaction costs of approximately $11,000 plus an earnout provision calculated through calendar year 2020 based upon revenue generated by the facility but limited to $1.8 million . The cash payment was funded by working capital. The purchased facility includes production equipment similar to TC's plus equipment that broadens TC's capabilities and potential markets. The 6.5 -acre site also includes substantial storage capacity, several rail and truck loading sites and utility tie-ins to TC. We refer to the facility as "B Plant". We have accounted for the purchase in accordance with the acquisition method of accounting under Financial Accounting Standards Board Accounting Standards Codification Topic 805 "Business Combinations" ("ASC 805"). In accordance with ASC 805, we used our best estimates and assumptions to assign fair value to the tangible assets and liabilities acquired at the acquisition date. The assets and liabilities acquired have been included in our consolidated balance sheets and our consolidated statements of income since the date of acquisition. We recorded an $11.5 million bargain purchase gain on the transaction as calculated in the table below (in thousands). Cash paid $ 2,011 Estimated earnout liability 733 Purchase Price $ 2,744 Fixed assets at FMV Land 980 Site improvements 30 Buildings 1,350 Production equipment 11,933 14,293 Bargain purchase gain $ 11,549 The business acquired had been idle for the periods presented thus proforma financial presentation would be identical to our consolidated results. We began operating the new facility in June 2016.

CONCENTRATIONS OF REVENUES AND

CONCENTRATIONS OF REVENUES AND CREDIT RISK	12 Months Ended
	Dec. 31, 2018
Risks and Uncertainties [Abstract]
CONCENTRATIONS OF REVENUES AND CREDIT RISK	CONCENTRATIONS OF REVENUES AND CREDIT RISK We sell our products and services to companies in the chemical, plastics, and petroleum industries. We perform periodic credit evaluations of our customers and generally do not require collateral from our customers. For the year ended December 31, 2018 , one customer accounted for 17.0% of consolidated product revenue. For the year ended December 31, 2017 , one customer accounted for 19.6% of consolidated product revenue. For the year ended December 31, 2016 , one customer accounted for 20.1% of consolidated product revenue. The associated accounts receivable balances for those customers were approximately $11.0 million at December 31, 2018 , and $5.8 million at December 31, 2017 . The carrying amount of accounts receivable approximates fair value at December 31, 2018 , and 2017 . Accounts receivable serves as collateral for our amended and restated loan agreement (see Note 12). We market our products in many foreign jurisdictions. For the years ended December 31, 2018 , 2017 and 2016 , specialty petrochemical product sales revenue in foreign jurisdictions accounted for approximately 35.4% , 20.8% , and 23.5% of total product sales revenue, respectively. SHR utilizes one major supplier for its feedstock supply. The feedstock is a commodity product commonly available from other suppliers if needed. The percentage of feedstock purchased from the supplier during 2018 , 2017 , and 2016 was 100% , 100.0% and 99% , respectively. At December 31, 2018 , and 2017 , we owed the supplier approximately $4.7 million and $8.5 million , respectively for feedstock purchases. We hold our cash with various financial institutions that are insured by the Federal Deposit Insurance Corporation up to $250,000 . At times during the year, cash balances may exceed this limit. We have not experienced any losses in such accounts and do not believe we are exposed to any significant risk of loss related to cash.

TRADE RECEIVABLES

TRADE RECEIVABLES	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
TRADE RECEIVABLES	TRADE RECEIVABLES Trade receivables, net, at December 31, consisted of the following: 2018 2017 (thousands of dollars) Trade receivables $ 27,564 $ 26,079 Less allowance for doubtful accounts (452 ) (300 ) Trade receivables, net $ 27,112 $ 25,779 Trade receivables serves as collateral for our amended and restated loan agreement with a domestic bank (see Note 12).

PREPAID EXPENSES AND OTHER ASSE

PREPAID EXPENSES AND OTHER ASSETS	12 Months Ended
	Dec. 31, 2018
Prepaid Expense and Other Assets, Current [Abstract]
PREPAID EXPENSES AND OTHER ASSETS	PREPAID EXPENSES AND OTHER ASSETS Prepaid expenses and other assets at December 31 are summarized as follows: 2018 2017 (thousands of dollars) Prepaid license $ 2,419 $ 1,919 Spare parts 1,597 954 Other prepaid expenses and assets 648 772 Total $ 4,664 $ 3,645 Beginning January 1, 2017, due to the expansion of our plant assets at SHR and TC, we began inventorying spare parts for the repair and maintenance of our plant, pipeline and equipment. Prepaid catalyst has been reclassified into Plant, Pipeline & Equipment to conform to current year reporting.

INVENTORIES

INVENTORIES	12 Months Ended
	Dec. 31, 2018
Inventory Disclosure [Abstract]
INVENTORIES	INVENTORIES Inventories include the following at December 31: 2018 2017 (thousands of dollars) Raw material $ 4,742 $ 3,703 Work in process 173 27 Finished products 11,624 14,720 Total inventory $ 16,539 $ 18,450 Inventory serves as collateral for our amended and restated loan agreement with a domestic bank (see Note 12). Inventory included products in transit valued at approximately $4.1 million and $3.7 million at December 31, 2018 , and 2017 , respectively.

PLANT, PIPELINE AND EQUIPMENT

PLANT, PIPELINE AND EQUIPMENT	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
PLANT, PIPELINE AND EQUIPMENT	PLANT, PIPELINE AND EQUIPMENT Plant, pipeline and equipment include the following at December 31: 2018 2017 (thousands of dollars) Platinum catalyst $ 1,612 $ 1,612 Catalyst 3,131 779 Land 5,428 5,428 Plant, pipeline and equipment 253,905 186,946 Construction in progress 4,343 50,996 Total plant, pipeline and equipment 268,419 245,761 Less accumulated depreciation (73,762 ) (63,240 ) Net plant, pipeline and equipment $ 194,657 $ 182,521 Plant, pipeline and equipment serve as collateral for our amended and restated loan agreement with a domestic bank (see Note 12). Interest capitalized for construction for 2018 , 2017 and 2016 was approximately $731,000 , $937,000 and $450,000 , respectively. Labor capitalized for construction for 2018 , 2017 and 2016 was approximately $2,307,000 , $4,344,000 and $2,889,000 , respectively. Catalyst amortization relating to the platinum catalyst which is included in cost of sales was approximately $59,000 , $25,000 and $98,000 for 2018 , 2017 and 2016 , respectively.

GOODWILL AND INTANGIBLE ASSETS,

GOODWILL AND INTANGIBLE ASSETS, NET	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND INTANGIBLE ASSETS, NET	GOODWILL AND INTANGIBLE ASSETS, NET Goodwill We performed an impairment analysis on the value of Goodwill at December 31, 2018 , and 2017 , and determined that no impairment existed. Intangible Assets The following table summarizes the gross carrying amounts and accumulated amortization of intangible assets by major class (in thousands): December 31, 2018 Intangible assets subject to amortization (Definite-lived) Gross Accumulated Amortization Net Customer relationships $ 16,852 $ (4,775 ) $ 12,077 Non-compete agreements 94 (80 ) 14 Licenses and permits 1,471 (495 ) 976 Developed technology 6,131 (2,606 ) 3,525 24,548 (7,956 ) 16,592 Intangible assets not subject to amortization (Indefinite-lived) Emissions Allowance 197 — 197 Trade name 2,158 — 2,158 Total $ 26,903 $ (7,956 ) $ 18,947 December 31, 2017 Intangible assets subject to amortization (Definite-lived) Gross Accumulated Amortization Net Customer relationships $ 16,852 $ (3,651 ) $ 13,201 Non-compete agreements 94 (61 ) 33 Licenses and permits 1,471 (390 ) 1,081 Developed technology 6,131 (1,993 ) 4,138 24,548 (6,095 ) 18,453 Intangible assets not subject to amortization (Indefinite-lived) Emissions Allowance 197 — 197 Trade name 2,158 — 2,158 Total $ 26,903 $ (6,095 ) $ 20,808 Amortization expense for intangible assets included in cost of sales for the years ended December 31, 2018 , 2017 , and 2016 , was approximately $1,861,000 , $1,861,000 , and $1,880,000 respectively. Based on identified intangible assets that are subject to amortization as of December 31, 2018 , we expect future amortization expenses for each period to be as follows (in thousands): Total 2019 2020 2021 2022 2023 Thereafter Customer relationships $ 12,077 $ 1,123 $ 1,123 $ 1,123 $ 1,123 $ 1,123 $ 6,462 Non-compete agreements 14 14 — — — — — Licenses and permits 976 106 106 101 86 86 491 Developed technology 3,525 613 613 613 613 613 460 Total future amortization expense $ 16,592 $ 1,856 $ 1,842 $ 1,837 $ 1,822 $ 1,822 $ 7,413

INVESTMENT IN AL MASANE AL KOBR

INVESTMENT IN AL MASANE AL KOBRA MINING COMPANY ("AMAK")	12 Months Ended
	Dec. 31, 2018
Equity Method Investments and Joint Ventures [Abstract]
INVESTMENT IN AL MASANE AL KOBRA MINING COMPANY (AMAK)	INVESTMENT IN AL MASANE AL KOBRA MINING COMPANY ("AMAK") We have concluded that we have significant influence over the operating and financial policies of AMAK and, accordingly, should account for our investment in AMAK using the equity method. As of December 31, 2018 , and 2017 , we had a non-controlling equity interest of approximately $38.7 million and $45.1 million , respectively. We have received and attached to this Form 10-K the financial statements of AMAK prepared in accordance with generally accepted accounting principles in the United States of America as of December 31, 2018 , and 2017 , and for each of the three years ended December 31, 2018 . These financial statements have been prepared in the functional currency of AMAK which is the Saudi Riyal (SR). In June 1986 the SR was officially pegged to the U.S. Dollar (USD) at a fixed exchange rate of 1 USD to 3.75 SR. The summarized results of operation and financial position for AMAK are as follows: Results of Operations Years Ended December 31, 2018 2017 2016 (Thousands of Dollars) Sales $ 70,234 $ 36,435 $ 9,921 Cost of sales (68,084 ) (43,304 ) (27,132 ) Gross loss 2,150 (6,869 ) (17,211 ) General, administrative and other expenses 8,879 9,903 9,690 Loss from operations $ (6,729 ) $ (16,772 ) $ (26,901 ) Gain on settlement with former operator — — 17,425 Net loss $ (6,729 ) $ (16,772 ) $ (9,476 ) Depreciation and amortization 33,469 22,419 11,672 Net income before depreciation and amortization $ 26,740 $ 5,648 $ 2,196 Financial Position December 31, 2018 2017 (Thousands of Dollars) Current assets $ 44,093 $ 23,333 Noncurrent assets 212,291 237,875 Total assets $ 256,384 $ 261,208 Current liabilities $ 17,160 $ 24,439 Long term liabilities 77,366 68,837 Shareholders' equity 161,858 167,932 Total liabilities and equity $ 256,384 $ 261,208 The equity in the income or loss of AMAK reflected on the consolidated statements of income for the years ended December 31, 2018 , 2017 , and 2016 , is comprised of the following: 2018 2017 2016 AMAK Net Loss $ (6,729 ) $ (16,772 ) $ (9,476 ) Zakat tax applicable to Saudi Arabian shareholders only — — 320 AMAK Net Loss before Saudi Arabian shareholders' portion of Zakat $ (6,729 ) $ (16,772 ) $ (9,156 ) Company's share of loss reported by AMAK (33.41% beginning July 10, 2016 and 35.25% prior to July 10, 2016) $ (2,248 ) $ (5,608 ) $ (2,826 ) Amortization of difference between Company's investment in AMAK and Company's share of net assets of AMAK 1,347 1,347 1,347 Equity in loss of AMAK $ (901 ) $ (4,261 ) $ (1,479 ) In 2016 the difference between our effective share of income (loss) from our investment and our actual ownership percentage is attributable to the change in our ownership percentage during the third quarter of 2016. A gain of approximately $16.2 million for the difference between our initial investment in AMAK and our share of AMAK's initial assets recorded at fair value was not recognized in 2008. This basis difference is being amortized over the life of AMAK's mine which is estimated to be twelve years beginning with its commencement of production in July 2012 as an adjustment to our equity in AMAK's income or loss. In July 2016 AMAK issued four million shares to provide additional funds for ongoing exploration work and mine start-up activities. Arab Mining Co. ("Armico") purchased 3.75 million shares at SR 20 per share (USD 5.33 per share) and the remaining 250,000 shares are for future use as employee incentives. We did not participate in the offering, thereby reducing our ownership percentage in AMAK to 33.44% from 35.25% . As a result of the equity issuance, our share of the net assets of AMAK increased approximately $3.2 million which we recognized as a gain (with a corresponding increase in our investment) in accordance with ASC 323-10-40-1. In 2018, we completed an exchange of shares with certain shareholders whereby such shareholders traded 65,000 common shares of TREC in exchange for 24,489 shares of our AMAK stock. The 65,000 shares were accounted for as treasury stock. This transaction reduced our ownership percentage from 33.44% to 33.41% . The following table shows AMAK shareholders and percentages owned at December 31, 2018: Name Percentage Owned Various Saudi shareholders 46.73 % Trecora Resources 33.41 % Armico 19.86 % Total 100.00 % As previously announced, AMAK initiated a share repurchase program from its existing shareholders in December 2018. We participated in this share repurchase and received approximately $5.3 million in proceeds from AMAK. We had previously reported, based on information available at the time, that AMAK was repurchasing 10% of its outstanding shares from its existing shareholders on a pro-rata basis. We have since learned that, while a redemption of up to 10% of AMAK's 82 million outstanding shares had been approved by the shareholders, the repurchase program approved by AMAK's board of directors and initiated in December 2018 was with respect to 2.5 million shares. AMAK expects to complete the share repurchase program in 2019, at which point all shares repurchased from AMAK shareholders will be registered as treasury shares. Upon completion of the share repurchase program, the Company does not believe its ownership percentage in AMAK will change from 33.4% . At December 31, 2018 and 2017, we had a receivable from AMAK of approximately $54,000 and $121,000 , respectively, relating to unreimbursed travel and Board expenses which is included in prepaid and other assets. We assess our investment in AMAK for impairment when events are identified, or there are changes in circumstances that may have an adverse effect on the fair value or recoverability of the investment. We consider recoverable ore reserves and the amount and timing of the cash flows to be generated by the production of those reserves, as well as, recent equity transactions within AMAK. No impairment charges were recorded in 2018 , 2017 , or 2016 .

MINERAL PROPERTIES IN THE UNITE

MINERAL PROPERTIES IN THE UNITED STATES	12 Months Ended
	Dec. 31, 2018
Mineral Industries Disclosures [Abstract]
MINERAL PROPERTIES IN THE UNITED STATES	MINERAL PROPERTIES IN THE UNITED STATES The principal assets of PEVM are an undivided interest in 48 patented and 5 unpatented mining claims totaling approximately 1,500 acres, and a 300 ton-per-day mill located on the aforementioned properties in the PEVM Mining District in southeast Nevada. In August 2001 seventy-five unpatented claims were abandoned since they were deemed to have no future value to PEVM. The properties held by PEVM have not been commercially operated for approximately 35 years.

LONG-TERM DEBT AND LONG-TERM OB

LONG-TERM DEBT AND LONG-TERM OBLIGATIONS	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
LONG-TERM DEBT AND LONG-TERM OBLIGATIONS	LONG-TERM DEBT AND LONG-TERM OBLIGATIONS ARC Agreement In October 2014, TOCCO, SHR, GSPL and TC (SHR, GSPL and TC collectively the “Guarantors”) entered into an amended and restated credit agreement (as amended to the date hereof, the “ARC Agreement”), which originally provided (i) a revolving credit facility (the “Revolving Facility”) with revolving commitments of $40.0 million and (ii) term loan borrowings consisting of (A) a $70.0 million single advance term loan incurred to partially finance the acquisition of TC (which we refer to as the “Acquisition loan”) and (B) a $25.0 multiple advance term loan facility for which borrowing availability ended on December 31, 2015 (collectively, the “Term Loan Facility” and, together with the Revolving Facility, the “Credit Facilities”). Only July 31, 2018, TOCCO and the Guarantors entered into a Fourth Amendment to the ARC Agreement (the “Fourth Amendment”) pursuant to which the revolving commitments under the Revolving Facility were increased to $75.0 million . Pursuant to the Fourth Amendment, total borrowings under the Term Loan Facility were increased to $87.5 million under a single combined term loan, which comprised new term loan borrowings together with approximately $60.4 million of previously outstanding term loans under the Term Loan Facility. The $60.4 million of previously outstanding term loans included the remaining outstanding balances on the Acquisition loan and the multiple advance term loan facility described above. Proceeds of the new borrowings under the Term Loan Facility were used to repay a portion of the outstanding borrowings under the Revolving Facility and pay fees and expenses of the transaction. As of December 31, 2018, we had $18 million in borrowings outstanding under the Revolving Facility and $84.5 million in borrowings outstanding under the Term Loan Facility. In addition, we had approximately $18 million of available borrowings under our Revolving Facility at December 31, 2018. TOCCO’s ability to make additional borrowings under the Revolving Credit Facility at December 31, 2018 was limited by, and in the future may be limited by our obligation to maintain compliance with the covenants contained in the ARC Agreement (including maintenance of a maximum Consolidated Leverage Ratio and minimum Consolidated Fixed Charge Coverage Ratio (each as defined in the ARC Agreement)). The maturity date for the ARC Agreement is July 31, 2023. Subject to the lenders acceptance of any increased commitment and other conditions, we have the option, at any time, to request an increase to the commitment under the Revolving Facility and/or the Term Loan Facility by an additional amount of up to $50.0 million in the aggregate. Borrowings under each of the Credit Facilities bear interest on the outstanding principal amount at a rate equal to LIBOR plus an applicable margin of 1.25% to 2.50% or, at our option, the Base Rate plus an applicable margin of 0.25% to 1.50% , in each case, with the applicable margin being determined based on the Consolidated Leverage Ratio of TOCCO. A commitment fee between 0.20% and 0.375% is also payable quarterly on the unused portion of the Revolving Facility. For 2018, the effective interest rate for the Credit Facilities was 4.19% . Borrowings under the Term Loan Facility are subject to quarterly amortization payments based on a commercial style amortization method over a twenty year period; provided, that the final principal installment will be paid on the maturity date and will be in an amount equal to the outstanding borrowings under the Term Loan Facility on such date. Pursuant to the terms of the ARC Agreement, TOCCO must maintain a maximum Consolidated Leverage Ratio of 4.75 to 1.00 for the four fiscal quarters ended December 31, 2018, 4.25 to 1.00 for the four fiscal quarters ended March 31, 2019, 4.00 to 1.00 for the four fiscal quarters ended June 30, 2019 and 3.75 to 1.00 for the four fiscal quarters ended September 30, 2019. For the four fiscal quarters ended December 31, 2019 and each fiscal quarter thereafter, TOCCO must maintain a Consolidated Leverage Ratio of 3.50 to 1.00 (subject to temporary increase following certain acquisitions). Additionally, TOCCO must maintain a minimum Consolidated Fixed Charge Coverage Ratio as of the end of any fiscal quarter of 1.15 to 1.00 . The ARC Agreement contains, among other things, other customary covenants, including restrictions on the incurrence of additional indebtedness, the granting of additional liens, the making of investments, the disposition of assets and other fundamental changes, transactions with affiliates and the declaration of dividends and other restricted payments. The ARC Agreement further includes customary representations and warranties and events of default, and upon occurrence of such events of default the outstanding obligations under the ARC Agreement may be accelerated and become immediately due and payable and the commitment of the lenders to make loans under the ARC Agreement may be terminated. We were in compliance with all covenants at December 31, 2018. Principal payments of long-term debt for the next five years and thereafter ending December 31 are as follows: Year Ending December 31, Long-Term Debt (thousands of dollars) 2019 4,375 2020 4,375 2021 4,375 2022 4,375 2023 85,812 Total 103,312 Debt Issuance Costs Debt issuance costs of approximately $0.9 million were incurred in connection with the Fourth Amendment and the remaining debt issuance costs of $0.3 million from the previous agreements were expensed and are shown as a loss on the extinguishment of debt on the consolidated statements of operations for the year ended December 31, 2018. Unamortized debt issuance costs of approximately $0.8 million and $0.5 million for the years ended December 31, 2018 and December 31, 2017, have been netted against outstanding loan balances. Long-term debt and long-term obligations at December 31 are summarized as follows: 2018 2017 (thousands of dollars) Revolving facility $ 18,000 $ 35,000 Term loan facility 85,312 47,250 Acquisition loan — 17,333 Loan fees (830 ) (501 ) Total long-term debt 102,482 99,082 Less current portion including loan fees 4,194 8,061 Total long-term debt, less current portion including loan fees $ 98,288 $ 91,021

ACCRUED LIABILITIES

ACCRUED LIABILITIES	12 Months Ended
	Dec. 31, 2018
Accrued Liabilities [Abstract]
ACCRUED LIABILITIES	ACCRUED LIABILITIES Accrued liabilities at December 31 are summarized as follows: 2018 2017 (thousands of dollars) Accrued state taxes $ 210 $ 272 Accrued payroll 936 1,407 Accrued interest 31 30 Accrued officer compensation — 500 Accrued restructuring & severance expenses (Note 21) 1,221 — Accrued foreign taxes 802 — Other liabilities 2,239 1,752 Total $ 5,439 $ 3,961

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Guarantees On October 24, 2010, we executed a limited guarantee in favor of the Saudi Industrial Development Fund ("SIDF") whereby we agreed to guaranty up to 41% of the SIDF loan to AMAK in the principal amount of 330.0 million Saudi Riyals (US $88.0 million ) (the "Loan"). The term of the loan is currently through June 2022. As a condition of the Loan, SIDF required all shareholders of AMAK to execute personal or corporate guarantees; as a result, the Company's guarantee is for approximately 135.3 million Saudi Riyals (US $36.1 million ). The loan was necessary to continue construction of the AMAK facilities and provide working capital needs. Our current assessment is that the probability of contingent performance is remote based on our analysis of the contingent portion of the guarantee which included but was not limited to the following: (1) the SIDF has historically not called guarantees, (2) the value of the assets exceeds the amount of the loan (3) the other shareholders have indicated that they would prioritize their personal guarantees ahead of the corporate guarantee, and (4) according to Saudi Arabian legal counsel, assets outside of Saudi Arabia are protected from the Saudi Court System. We received no consideration in connection with extending the guarantee and did so to maintain and enhance the value of our investment. Our non-contingent and immediate obligation to stand ready to make payments if the events of default under the guarantee occur was not material to the financial statements. The total amount outstanding to the SIDF at December 31, 2018 , and 2017 was 305.0 million and 305.0 million Saudi Riyals (US $81.3 million and $81.3 million ), respectively. Operating Lease Commitments We have operating leases for the rental of approximately 346 railcars for shipping purposes with expiration dates through 2026 . Invoices are received and paid on a monthly basis. The total amount of the commitment is approximately $17.3 million over the next 9 years. We also have an operating lease for our office space in Sugar Land, Texas. The expiration date for this lease is September 2023 . The total amount of the commitment is approximately $587,000 . In addition, we are required to make periodic payments for property taxes, utilities and common area operating expenses. In addition, we have operating leases for other equipment such as forklifts and copiers with varying expiration dates through 2023 . These commitments are approximately $207,000 . Future minimum property and equipment lease payments under the non-cancelable operating leases at December 31, 2018 , are as follows: Year Ending December 31, (thousands of dollars) 2019 $ 3,670 2020 3,583 2021 3,418 2022 3,107 2023 2,288 Thereafter 2,065 Total $ 18,131 Rental expense for these operating leases for the years ended December 31, 2018 , 2017 , and 2016 was $4.4 million , $4.4 million and $4.2 million , respectively. Litigation From time to time, we may become party to litigation or other legal proceedings that we consider to be a part of the ordinary course of our business. We are not currently involved in any legal proceedings that we believe could reasonably be expected to have a material adverse effect on our business, prospects, financial condition or results of operations. We may become involved in material legal proceedings in the future. On March 21, 2011, Mr. El Khalidi filed suit against the Company in Texas alleging breach of contract and other claims. The 88th Judicial District Court of Hardin County, Texas dismissed all claims and counterclaims for want of prosecution in this matter on July 24, 2013. The Ninth Court of Appeals subsequently affirmed the dismissal for want of prosecution and the Supreme Court of Texas denied Mr. El Khalidi's petition for review. On May 1, 2014, Mr. El Khalidi refiled his lawsuit against the Company for breach of contract and defamation in the 356th Judicial District Court of Hardin County, Texas. The case was transferred to the 88th Judicial District Court of Hardin County, Texas. The Trial Court dismissed all of Mr. El Khalidi's claims and causes of action with prejudice and the Ninth Court of Appeals affirmed. Mr. El Khalidi filed a petition for review with the Supreme Court of Texas, which was denied April 6, 2018. Mr. El Khalidi filed a motion for rehearing of his petition for review with the Supreme Court of Texas on April 23, 2018. On May 25, 2018, the Supreme Court of Texas denied the motion for rehearing and the matter is considered closed. Supplier Agreements From time to time, we may incur shortfall fees due to feedstock purchases being below the minimum amounts as prescribed by our agreements with our suppliers. The shortfall fee expenses were not significant for the years ended December 31, 2018 , 2017 , and 2016 . Environmental Remediation Amounts charged to expense for various activities related to environmental monitoring, compliance, and improvements were approximately $745,000 in 2018 , $593,000 in 2017 and $622,000 in 2016 .

SHARE-BASED COMPENSATION

SHARE-BASED COMPENSATION	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
SHARE-BASED COMPENSATION	SHARE-BASED COMPENSATION The Stock Option Plan for Key Employees, as well as, the Non-Employee Director Stock Option Plan (hereinafter collectively referred to as the “Stock Option Plans”), were approved by the Company’s shareholders in July 2008. The Stock Option Plans allot for the issuance of up to 1,000,000 shares. The Trecora Resources Stock and Incentive Plan (the “Plan”) was approved by the Company’s shareholders in June 2012. The Plan allots for the issuance of up to 1,500,000 shares in the form of stock options or restricted stock unit awards. Share-based compensation of approximately $ 1.8 million, $2.7 million, and $2.6 million was recognized in 2018, 2017, and 2016, respectively. The Company reclassified approximately $318,000 for 2018 from share-based compensation expense in connection with the restructuring described in Note 21. Stock Options and Warrant Awards Stock options and warrants granted under the provisions of the Stock Option Plans permit the purchase of our common stock at exercise prices equal to the closing price of Company common stock on the date the options were granted. The options have terms of 10 years and generally vest ratably over terms of 4 to 5 years. There were no stock options or warrant awards issued during 2018, 2017, or 2016. A summary of the status of the Company’s stock option and warrant awards is as follows: Stock Options and Warrants Weighted Average Exercise Price Per Share Weighted Average Remaining Contractual Life Intrinsic Value (in thousands) Outstanding at January 1, 2018 1,323,587 $ 7.82 Granted — — Expired — — Exercised (377,757 ) 5.21 Forfeited (200,000 ) 3.40 Outstanding at December 31, 2018 745,830 $ 10.33 4.6 $ — Expected to vest — $ — 0.0 $ — Exercisable at December 31, 2018 745,830 $ 10.33 4.6 $ — The aggregate intrinsic value of options was calculated as the difference between the exercise price of the underlying awards and the quoted price of our common stock. At December 31, 2018, options to purchase approximately 0.5 million shares of common stock were in-the-money. Since no options were granted, the weighted average grant-date fair value per share of options granted during the years 2018, 2017, and 2016 was $0 . During 2018, 2017, and 2016 the aggregate intrinsic value of options and warrants exercised was approximately $2,630,000 , $164,000 and $237,000 respectively, determined as of the date of option exercise. The Company received approximately $912,000 , $25,000 and $11,000 in cash from the exercise of options during 2018, 2017 and 2016, respectively. Of the approximately 378,000 stock options and warrants exercised, the Company only issued approximately 268,000 shares due to cashless transactions. The tax benefit realized from the exercise was insignificant. A summary of the status of the Company's non-vested options that are expected to vest is presented below: Shares Weighted Average Grant-Date Fair Value Per Share Non-vested at January 1, 2018 325,000 $ 6.81 Granted — — Forfeited (200,000 ) 3.40 Vested (125,000 ) 12.26 Non-vested at December 31, 2018 — $ — Total fair value of options that vested during 2018 was approximately $1,533,000 . As of December 31, 2018 , there was no unrecognized compensation costs related to non-vested share-based compensation. Post-retirement compensation of approximately $680,000 and $0 during the years ended December 31, 2018 and 2017 , respectively, was reversed related to options awarded to Mr. Hatem El Khalidi in July 2009. On May 9, 2010, the Board of Directors determined that Mr. El Khalidi forfeited these options and other retirement benefits when he made various demands against the Company and other AMAK shareholders which would benefit him personally and were not in the best interests of the Company and its shareholders. The Company was successful in litigating its right to withdraw the options and benefits and as such, these options and benefits were reversed during the second quarter of 2018. Restricted Stock and Restricted Stock Unit Awards Generally, restricted stock and restricted stock unit awards are granted annually to officers and directors of the Company under the provisions of the Plan. Restricted stock units are also granted ad hoc to attract or retain key personnel, and the terms and conditions under which these restricted stock units vest vary by award. The fair market value of restricted stock units granted is equal to the Company’s closing stock price on the date of grant. Restricted stock units granted generally vest ratably over periods ranging from 2.5 to 5 years. Certain awards also include vesting provisions based on performance metrics. Upon vesting, the restricted stock units are settled by issuing one share of Company common stock per unit. A summary of the status of the Company's restricted stock units activity is as follows: Shares of Restricted Stock Units Weighted Average Grant Date Price per Share Outstanding at January 1, 2018 387,702 $ 11.39 Granted 226,908 11.45 Forfeited (103,637 ) 11.39 Vested (105,298 ) 11.99 Outstanding at December 31, 2018 405,675 $ 11.27 Expected to vest 405,675 As of December 31, 2018 , there was approximately $2.5 million of unrecognized compensation costs related to non-vested restricted share-based compensation that is expected to be recognized over a weighted average period of 1.9 years.

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES The provision for income taxes consisted of the following: Year ended December 31, 2018 2017 2016 (thousands of dollars) Current federal provision (benefit) $ (74 ) $ (1,202 ) $ 1,691 Current state provision 31 282 18 Deferred federal provision (benefit) (974 ) (6,320 ) 8,645 Deferred state provision 210 81 150 Income tax expense (benefit) $ (807 ) $ (7,159 ) $ 10,504 In connection with the AMAK share repurchase discussed in Note 10, the Company anticipates a Saudi Arabian income tax liability of approximately $802,000 . This amount is included in accrued liabilities and will be paid once the transaction is complete. We had no Saudi Arabian income tax expense or liability in 2017 or 2016 . The difference between the effective tax rate in income tax expense and the Federal statutory rate of 21% for the year ended December 31, 2018 , and 35% for the years ended December 31 2017 and 2016 , is as follows: 2018 2017 2016 (thousands of dollars) Income taxes at U.S. statutory rate $ (822 ) $ 3,885 $ 10,476 State taxes, net of federal benefit 234 235 285 Net operating loss carryback — (961 ) — Research and development credits (263 ) — — Permanent and other items 44 (11 ) (257 ) Deferred tax impact of US tax reform — (10,307 ) — Total tax expense (benefit) $ (807 ) $ (7,159 ) $ 10,504 Permanent differences are primarily due to the Federal manufacturer's deduction, research and development credit, and stock based compensation. The Company has recognized the provisional tax impacts related to the acceleration of depreciation and included these amounts in its consolidated financial statements for the year ended December 31, 2018 . After the analysis, the Company did not identify items for which the income tax effects of the TCJA have not been completed and a reasonable estimate could not be determined as of December 31, 2018 . The changes to existing U.S. tax laws as a result of the TCJA, which will have the most significant impact on the Company's federal income taxes are as follows: Reduction of the U.S. Corporate Income Tax Rate - The Company uses the asset and liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to reverse. As a result of the reduction in the U.S. corporate income tax rate from 35% to 21% under the TCJA, the Company revalued its ending net deferred tax liabilities at December 31, 2017 . Acceleration of Depreciation - The Company recognized a provisional reduction to net deferred tax assets attributable to the accelerated depreciation for certain assets placed into service after September 27, 2017. The provisional estimate was finalized including consideration of TCJA on long term construction projects. Tax effects of temporary differences that give rise to significant portions of federal and state deferred tax assets and deferred tax liabilities were as follows: December 31, 2018 2017 (thousands of dollars) Deferred tax liabilities: Plant, pipeline and equipment $ (25,169 ) $ (17,014 ) Intangible assets (1,075 ) (778 ) Other assets (40 ) (4 ) Investment in AMAK (671 ) (1,023 ) Total deferred tax liabilities $ (26,955 ) $ (18,819 ) Deferred tax assets: Accounts receivable 238 198 Inventory 133 156 Mineral interests 226 226 Foreign tax credit 802 — Net operating loss carryforward 9,073 — Post-retirement benefits 79 252 Stock-based compensation 954 971 Gross deferred tax assets 11,505 1,803 Valuation allowance (226 ) (226 ) Total net deferred tax assets $ 11,279 $ 1,577 Net deferred tax liabilities $ (15,676 ) $ (17,242 ) In connection with the proceeds received from AMAK in connection with its share repurchase program, the Company accrued a deferred tax asset (foreign tax credit) and the corresponding liability for the anticipated Saudi Arabian tax. We provided a valuation allowance in 2018 and 2017 against certain deferred tax assets because of uncertainties regarding their realization. There was no change in the valuation allowance for 2018 or 2017 . We file an income tax return in the U.S. federal jurisdiction and a margin tax return in Texas. We received notification from the Internal Revenue Service ("IRS") in November 2016 on the selection of the December 31, 2014 tax return for audit. The IRS expanded its audit to include the Research and Development ("R&D") Credits for the year ended December 31, 2015. The IRS closed its audit without change in March 2018. We also received notification that Texas will audit our R&D credit calculations for 2014 and 2015. The state of Texas has suspended the audit of the Company's R&D credit. Texas is comprehensively reviewing their audit procedures for consistency. We do not expect any changes related to the Texas audits. Our federal and Texas tax returns remain open for examination for the years 2015 through 2018. We recognized no adjustment for uncertain tax positions. As of December 31, 2018 , and 2017 , no interest or penalties related to uncertain tax positions had been accrued.

SEGMENT INFORMATION

SEGMENT INFORMATION	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
SEGMENT INFORMATION	SEGMENT INFORMATION We operate in two business segments; specialty petrochemical and specialty waxes. We operate through business segments according to the nature and economic characteristics of our products as well as the manner in which the information is used internally by our key decision maker, who is our Chief Executive Officer. The accounting policies of the reporting segments are the same as those described in Note 2. Our specialty petrochemical segment includes SHR and GSPL. Our specialty wax segment includes TC. We also separately identify our corporate overhead which includes financing and administrative activities such as legal, accounting, consulting, investor relations, officer and director compensation, corporate insurance, and other administrative costs. Year Ended December 31, 2018 Specialty Petrochemical Specialty Wax Corporate Consolidated (in thousands) Net revenues $ 249,679 $ 38,253 $ — $ 287,932 Operating profit (loss) before depreciation and amortization 23,021 1,949 (8,275 ) 16,695 Operating profit (loss) 14,089 (3,427 ) (8,327 ) 2,335 Profit (loss) before taxes 10,705 (4,660 ) (9,184 ) (3,139 ) Depreciation and amortization 8,932 5,376 50 14,358 Capital expenditures 22,431 2,854 — 25,285 Year Ended December 31, 2018 Specialty Petrochemical Specialty Wax Corporate Eliminations Consolidated (in thousands) Goodwill and intangible assets, net $ — $ 40,745 $ — $ — $ 40,745 Total assets 284,367 115,366 91,474 (161,239 ) 329,968 Year Ended December 31, 2017 Specialty Petrochemical Specialty Wax Corporate Consolidated (in thousands) Net revenues $ 210,381 $ 34,762 $ — $ 245,143 Operating profit (loss) before depreciation and amortization 36,511 (35 ) (7,413 ) 29,063 Operating profit (loss) 30,201 (4,624 ) (7,475 ) 18,102 Profit (loss) before taxes 27,852 (5,238 ) (11,764 ) 10,850 Depreciation and amortization 6,310 4,589 62 10,961 Capital expenditures 38 14,015 — 14,053 Year Ended December 31, 2017 Specialty Petrochemical Specialty Wax Corporate Eliminations Consolidated (in thousands) Goodwill and intangible assets, net $ — $ 42,606 $ — $ — $ 42,606 Total assets 265,213 117,579 97,880 (153,346 ) 327,326

NET INCOME (LOSS) PER COMMON SH

NET INCOME (LOSS) PER COMMON SHARE	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
NET INCOME (LOSS) PER COMMON SHARE	NET INCOME (LOSS) PER COMMON SHARE Year ended December 31, 2018 2017 2016 (thousands of dollars) Net income (loss) $ (2,332 ) $ 18,009 $ 19,428 Basic earnings (loss) per common share: Weighted average shares outstanding 24,438 24,294 24,284 Per share amount (dollars) $ (0.10 ) $ 0.74 $ 0.80 Diluted earnings (loss) per common share: Weighted average shares outstanding 24,438 25,129 24,982 Per share amount (dollars) $ (0.10 ) $ 0.72 $ 0.78 Weighted average shares-denominator basic computation 24,438 24,294 24,284 Unvested restricted stock unit grant — 367 310 Effect of dilutive stock options — 468 388 Weighted average shares, as adjusted denominator diluted computation 24,438 25,129 24,982 At December 31, 2018 , 2017 , and 2016 , 745,830 , 1,323,587 and 1,348,437 potential common stock shares, respectively, were issuable upon the exercise of options and warrants. At December 31, 2018, the Company had 397 unvested restricted stock units and 264 stock options that were not included in the computation of diluted earnings per share because the effect of conversion would be anti-dilutive due to the Company incurring net loss for operations for the year ended December 31, 2018. In 2018, we completed an exchange of shares with certain shareholders whereby such shareholders traded 65,000 common shares of TREC in exchange for 24,489 shares of our AMAK stock. The 65,000 shares were accounted for as treasury stock.

QUARTERLY RESULTS OF OPERATIONS

QUARTERLY RESULTS OF OPERATIONS (UNAUDITED)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
QUARTERLY RESULTS OF OPERATIONS (UNAUDITED)	QUARTERLY RESULTS OF OPERATIONS (UNAUDITED) The quarterly results of operations shown below are derived from unaudited financial statements for the eight quarters ended December 31, 2018 (in thousands, except per share data, rounding may apply): Year Ended December 31, 2018 First Quarter Second Quarter Third Quarter Fourth Quarter Total Revenues $ 71,741 $ 68,106 $ 73,416 $ 74,669 $ 287,932 Gross profit 10,140 8,142 6,842 2,694 27,818 Net income (loss) 2,352 2,215 (1,609 ) (5,290 ) (2,332 ) Basic EPS (1) $ 0.10 $ 0.09 $ (0.07 ) $ (0.22 ) $ (0.10 ) Diluted EPS (1) $ 0.09 $ 0.09 $ (0.07 ) $ (0.22 ) $ (0.10 ) Year Ended December 31, 2017 First Quarter Second Quarter Third Quarter Fourth Quarter (2) Total Revenues $ 55,542 $ 62,115 $ 61,508 $ 65,978 $ 245,143 Gross profit 10,618 11,107 9,870 9,966 41,561 Net income 1,487 832 1,718 13,972 18,009 Basic EPS (1) $ 0.06 $ 0.03 $ 0.07 $ 0.58 $ 0.74 Diluted EPS (1) $ 0.06 $ 0.03 $ 0.07 $ 0.56 $ 0.72 (1) Basic and diluted earnings per share are computed independently for each of the quarters presented based on the weighted average number of common shares outstanding during that period. Therefore, the sum of quarterly basic and diluted per share information may not equal annual basic and diluted earnings per share. (2) As discussed in Note 16 the TCJA changed the federal corporate income tax rates from 35% to 21% resulting in a benefit from deferred taxes of approximately $10.3 million .

RELATED PARTY TRANSACTIONS

RELATED PARTY TRANSACTIONS	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
RELATED PARTY TRANSACTIONS	RELATED PARTY TRANSACTIONS Consulting fees of approximately $28,000 , $27,000 and $33,000 were incurred during 2018 , 2017 , and 2016 , respectively from IHS Global FZ LLC of which Company Director Gary K. Adams held the position of Chief Advisor – Chemicals until April 1, 2017. At December 31, 2018 , and 2017 , we had no outstanding liability payable to IHS Global FZ LLC. Consulting fees of approximately $94,000 , $74,000 and $73,000 were incurred during 2018 , 2017 , and 2016 , respectively, from Chairman of the Board, Nicholas Carter. Due to his history and experience with the Company and to provide continuity after his retirement, a three year consulting agreement was entered into with Mr. Carter in July 2015. At December 31, 2018 , and 2017 , we had no outstanding liability payable to Mr. Carter.

RESTRUCTURING AND SEVERANCE EXP

RESTRUCTURING AND SEVERANCE EXPENSES	12 Months Ended
	Dec. 31, 2018
Restructuring and Related Activities [Abstract]
RESTRUCTURING AND SEVERANCE EXPENSES	NOTE 21 – RESTRUCTURING AND SEVERENCE EXPENSES During 2018, the Company incurred restructuring and severance expenses of approximately $2.3 million related to changes in executive management and the completion of projects in our specialty petrochemical segment. These expenses relate to severance, stock compensation for continued vesting of time-vested shares issued under the Company's long-term incentive plans, and certain employee benefits including medical insurance and vacation. As of December 31, 2018, approximately $1.2 million remains unpaid and is included in accrued liabilities.

POST-RETIREMENT OBLIGATIONS

POST-RETIREMENT OBLIGATIONS	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
POST-RETIREMENT OBLIGATIONS	POST-RETIREMENT OBLIGATIONS In January 2008, an amended retirement agreement was entered into with Mr. Hatem El Khalidi; however, on May 9, 2010, the Board of Directors terminated the agreement due to actions of Mr. El Khalidi. See Note 14. All amounts which had not met termination dates remained recorded until a resolution was achieved. The matter was resolved on May 25, 2018 and as of June 30, 2018, post-retirement obligations of approximately $1.0 million for Mr. El Khalidi have been reversed. As of December 31, 2017, approximately $1.0 million remained outstanding and was included in post-retirement benefits. In July 2015 and June 2018, we entered into retirement agreements with our former CEO, Nicholas Carter, and our former VP of Accounting & Compliance, Connie Cook. Mr. Carter's agreement provides continued welfare benefits for him and his wife for life at the same cost sharing basis as regular employees. Ms. Cook's agreement provides continued welfare benefits for her and her husband until eligible for Medicare. Approximately $377,000 and $249,000 was outstanding at December 31, 2018 , and 2017 , respectively, and included in post-retirement benefits. For the period ended December 31, 2018 , and 2017 , approximately $18,000 and $16,000 , respectively had been paid.

VALUATION AND QUALIFYING ACCOUN

VALUATION AND QUALIFYING ACCOUNTS	12 Months Ended
	Dec. 31, 2018
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
VALUATION AND QUALIFYING ACCOUNTS	TRECORA RESOURCES AND SUBSIDIARIES VALUATION AND QUALIFYING ACCOUNTS Three years ended December 31, 2018 Description Beginning balance Charged (credited) to earnings Deductions Ending balance ALLOWANCE FOR DEFERRED TAX ASSET December 31, 2016 376,037 — — 376,037 December 31, 2017 376,037 (150,415 ) — 225,622 December 31, 2018 225,622 — — 225,622 Description Beginning balance Charged to earnings Deductions Ending balance ALLOWANCE FOR DOUBTFUL ACCOUNTS December 31, 2016 210,000 183,339 (93,339 ) 300,000 December 31, 2017 300,000 — — 300,000 December 31, 2018 300,000 152,000 — 452,000

AMAK FINANCIAL STATEMENTS

AMAK FINANCIAL STATEMENTS	12 Months Ended
	Dec. 31, 2018
AMAK
Schedule of Equity Method Investments [Line Items]
FINANCIAL STATEMENTS	AL MASANE AL KOBRA MINING COMPANY Balance Sheets December 31, 2018 2017 (Expressed in Saudi Riyals) ASSETS Current assets: Cash and cash equivalents 31,510,496 32,325,537 Accounts receivable 16,235,035 8,213,816 Inventories 45,871,120 27,226,932 Advances to shareholders (Note 1) 52,562,028 — Advances to contractors and other 19,168,765 19,731,780 Total current assets 165,347,444 87,498,065 Non-current assets: Property and equipment, net 634,856,075 693,801,671 Development costs, net 155,281,525 191,528,180 Deferred mine closure costs 5,955,999 6,700,499 Total non-current assets 796,093,599 892,030,350 961,441,043 979,528,415 LIABILITIES AND SHAREHOLDERS' EQUITY Current liabilities: Accounts payable and accrued liabilities 28,756,945 22,672,618 Zakat and income tax liability 5,400,000 3,516,673 Due to shareholders — 453,816 Capital lease obligation, current portion 193,206 — Long-term debt, current portion 30,000,000 65,000,000 Total current liabilities 64,350,151 91,643,107 Non-current liabilities Provision for mine closure costs 16,063,136 15,519,938 Capital lease obligation, net of current portion 359,811 — Long-term debt, net of current portion and deferred finance costs 266,258,712 229,082,810 End-of-service indemnities 3,649,889 2,518,529 Deferred income taxes 3,792,785 11,017,714 Total non-current liabilities 290,124,333 258,138,991 AL MASANE AL KOBRA MINING COMPANY Balance Sheets - (Continued) December 31, 2018 2017 (Expressed in Saudi Riyals) Commitments and contingencies (Note 14) Shareholders' equity Share capital 820,000 780,000 Share premium — 37,546 Accumulated deficit (213,033 ) (187,800 ) Total shareholders' equity 606,967 629,746 961,441 979,528 AL MASANE AL KOBRA MINING COMPANY Statements of Operations December 31, 2018 2017 2016 (Expressed in Saudi Riyals) Revenues 263,377,273 136,629,881 37,202,504 Costs of revenues 255,313,296 162,388,373 101,743,839 Operating income (loss) 8,063,977 (25,758,492 ) (64,541,335 ) General and administrative expenses 29,475,998 28,299,733 26,957,555 Loss from operations (21,412,021 ) (54,058,225 ) (91,498,890 ) Other income (expense) Gain on forgiveness of liabilities and spare parts (Note 8) — — 65,345,250 Finance charges (5,969,821 ) (6,103,680 ) (6,043,410 ) Other income 323,575 893,524 260,953 (5,646,246 ) (5,210,156 ) 59,562,793 Loss before Zakat and income tax (27,058,267 ) (59,268,381 ) (31,936,097 ) Zakat and income tax benefit (expense) 1,824,929 (3,627,193 ) (3,596,244 ) Net loss (25,233,338 ) (62,895,574 ) (35,532,341 ) AL MASANE AL KOBRA MINING COMPANY Statements of Changes in Shareholders' Equity (Expressed in Saudi Riyals) Retained Earnings Share Share (Accumulated Capital Premium Deficit) Total Balance at December 31, 2015 740,000,000 — (89,372,188 ) 650,627,812 Issuance of share capital and premium 40,000,000 37,546,420 — 77,546,420 Net loss — — (35,532,341 ) (35,532,341 ) Balance at December 31, 2016 780,000,000 37,546,420 (124,904,529 ) 692,641,891 Net loss — — (62,895,574 ) (62,895,574 ) Balance at December 31, 2017 780,000,000 37,546,420 (187,800,103 ) 629,746,317 Issuance of share premium — 2,453,580 — 2,453,580 Conversion of share premium to share capital 40,000,000 (40,000,000 ) — — Net loss — — (25,233,338 ) (25,233,338 ) Balance at December 31, 2018 820,000,000 — (213,033,441 ) 606,966,559 AL MASANE AL KOBRA MINING COMPANY Statements of Cash Flows December 31, 2018 2017 2016 (Expressed in Saudi Riyals) Cash flows from operating activities: Net loss (25,233,338 ) (62,895,574 ) (35,532,341 ) Adjustments to reconcile net loss to net cash provided by (used in) operating activities: Depreciation and amortization 125,507,864 83,547,586 43,768,238 Accretion of deferred mine closure costs 543,198 524,829 507,081 Amortization of deferred finance costs 2,175,902 1,610,733 2,147,644 Gain on forgiveness of liabilities — — (65,345,250 ) Deferred income taxes (7,224,929 ) 417,966 1,718,258 Changes in operating assets and liabilities: Accounts receivable (8,021,219 ) (8,213,816 ) 28,351,618 Inventories (18,644,188 ) (11,351,752 ) 15,754,952 Advances to contractors and other 563,016 (3,944,995 ) (6,186,357 ) Accounts payable and accrued liabilities 6,084,327 9,638,009 3,511,632 Zakat and income tax liability 1,883,327 1,583,048 679,206 Pre-export advance payment — — (9,150,880 ) End-of-service indemnities 1,131,360 1,037,893 (264,797 ) Net cash provided by (used in) operating activities 78,765,320 11,953,927 (20,040,996 ) Cash flows from investing activities: Additions to property and equipment (28,945,309 ) (31,550,443 ) (29,246,001 ) AL MASANE AL KOBRA MINING COMPANY Statements of Cash Flows - (Continued) December 31, 2018 2017 2016 (Expressed in Saudi Riyals) Cash flows from financing activities: Issuance of share capital and premium 2,453,580 — 75,092,840 Payments on capital lease obligations (72,788 ) — — Payments on long-term debt — (5,000,000 ) — Net advances from (to) shareholders (53,015,844 ) 403,147 299,231 Net cash provided by (used in) financing activities (50,635,052 ) (4,596,853 ) 75,392,071 Increase (decrease) in cash and cash equivalents (815,041 ) (24,193,369 ) 26,105,074 Cash and cash equivalents, beginning of year 32,325,537 56,518,906 30,413,832 Cash and cash equivalents, end of year 31,510,496 32,325,537 56,518,906 Supplemental cash flow information Cash paid for interest 3,927,778 3,686,000 3,895,766 Cash paid for Zakat and income tax 3,212,813 1,626,179 1,198,780 Supplemental disclosure of non-cash items Assets acquired through capital lease obligations 625,805 — —

AMAK ORGANIZATION AND BUSINESS

AMAK ORGANIZATION AND BUSINESS	12 Months Ended
	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
ORGANIZATION AND BUSINESS	BUSINESS AND OPERATIONS OF THE COMPANY Trecora Resources, formerly Arabian American Development Company, (the "Company") was organized as a Delaware corporation in 1967. The Company's principal business activities are the manufacturing of various specialty petrochemical products, specialty waxes and providing custom processing services. The Company owns 33% of a Saudi Arabian joint stock company, Al Masane Al Kobra Mining Company ("AMAK") (see Note 10) and approximately 55% of the capital stock of a Nevada mining company, Pioche Ely Valley Mines, Inc. ("PEVM"), which does not conduct any substantial business activity but owns undeveloped properties in the United States. The Company's specialty petrochemical operations are primarily conducted through a wholly-owned subsidiary, Texas Oil and Chemical Co. II, Inc. ("TOCCO"). TOCCO owns all of the capital stock of South Hampton Resources, Inc. ("SHR") and Trecora Chemical, Inc. ("TC"). SHR owns all of the capital stock of Gulf State Pipe Line Company, Inc. ("GSPL"). SHR owns and operates a specialty petrochemical product facility near Silsbee, Texas which manufactures high purity hydrocarbons used primarily in polyethylene, packaging, polypropylene, expandable polystyrene, poly-iso/urethane foams, Canadian tar sands, and in the catalyst support industry. TC owns and operates a facility located in Pasadena, Texas which manufactures specialty waxes and provides custom processing services. These specialty waxes are used in the production of coatings, hot melt adhesives and lubricants. GSPL owns and operates pipelines that connect the SHR facility to a natural gas line, to SHR's truck and rail loading terminal and to a major petroleum pipeline owned by an unaffiliated third party. We attribute revenues to countries based upon the origination of the transaction. All of our revenues for the years ended December 31, 2018 , 2017 , and 2016 , originated in the United States. In addition, all of our long-lived assets are in the United States. For convenience in this report, the terms "Company", "our", "us" or "we" may be used to refer to Trecora Resources and its subsidiaries.
AMAK
Schedule of Equity Method Investments [Line Items]
ORGANIZATION AND BUSINESS	Note 1 – Organization and Business Organization Al Masane Al Kobra Mining Company is a Saudi Arabian closed joint stock company approved by the Minister of Commerce and Industry Decree Number 247/Q dated 9/10/1428 (October 21, 2007) and registered in Jeddah under Commercial Registration No. 4030175345 on 7/1/1429 (January 16, 2008). During 2015, the head office was moved from Jeddah to Najran. Accordingly, Najran Commercial Registration No. 5950017523 dated 03/11/1431H (October 11, 2010) was modified to be the main Commercial Registration. Unless the context requires otherwise, references to “we”, “us”, “our”, “AMAK”, and the “Company” are intended to mean Al Masane Al Kobra Mining Company. All amounts are expressed in Saudi Riyals (SR) unless otherwise noted. During 2009 the authorized capital of the Company was 450,000,000 consisting of 45 million shares of 10 each of which 50% were issued for cash. The remaining 50% were issued for the contribution of mining rights and assets from Trecora Resources (Trecora) subject to Trecora’s liability for a loan in the amount of 41,250,000 due to the Ministry of Finance and National Economy. The mining rights in Al Masane mine were originally granted by Royal Decree Number M/17 effective 1/12/1413 (May 22, 1993) for a period of thirty years, with a right of renewal for a further period of twenty years to Trecora. The mining rights granted Trecora the right of exploitation in Al Masane mine located in Najran, Saudi Arabia, with an area of 44 square kilometers for a surface rental of 10,000 per square kilometer per year, i.e. 440,000 per year. As per the Ministry of Petroleum and Mineral Resources resolution dated 13/9/1429 (13/9/2008) and the ministry subsequent letter dated 2/1/1430 (30/12/2008), the aforementioned rights were transferred to us. During 2011 the Company increased its authorized share capital by SR 50,000,000 to SR 500,000,000 and issued 5,000,000 shares of 10 each at a price of SR 28 each resulting in a share premium of SR 90,000,000 . The entire 5,000,000 shares were issued for cash to Arab Mining Company (ARMICO) headquartered in Amman, Jordan. During 2013 the Company increased its authorized share capital by SR 50,000,000 to SR 550,000,000 and issued 5,000,000 shares of 10 each at a price of SR 30 each resulting in a share premium of SR 100,000,000 . The shares were issued for cash to existing shareholders. During 2015 the Company increased its authorized share capital by SR 190,000,000 to SR 740,000,000 and issued 19,000,000 shares of 10 each by transferring from share premium accounts. During 2016 the Company increased its authorized share capital by SR 40,000,000 to SR 780,000,000 and issued 4,000,000 shares of 10 each at a price of SR 20 each resulting in a share premium of SR 35,092,840 . During 2018 the Company increased share premium by SR 2,453,580 for shares that were previously issued. During 2018 the Company increased its authorized share capital by SR 40,000,000 to SR 820,000,000 and issued 4,000,000 shares of 10 each by transferring from share premium accounts. During the Company’s Extraordinary General Assembly Meeting in October of 2018, the shareholders approved to repurchase 2,500,000 shares from the shareholders at a price of SR 30 each and to register these shares as treasury shares. In December 2018, the Board unanimously approved this proposal and authorized the CEO to proceed with the repurchase. The Company began advancing shareholders their portion of these proceeds in anticipation of completing and finalizing the treasury stock repurchase in 2019. As of December 31, 2018, the Company had advanced SR 52,562,028 to shareholders. Except for Trecora and ARMICO, all other shareholders are Saudi nationals or companies wholly owned by Saudi nationals. Our ownership is as follows: Shares Ownership Percentage Saudi shareholders 38,349,184 46.8 Trecora (US Company) 27,402,876 33.4 ARMICO (Pan Arab Organization) 16,247,940 19.8 82,000,000 100.00 Business and operations Our principal activity is to produce zinc and copper concentrates and silver and gold doré as per the license Number 993/2 dated 16/7/1428 (July 31, 2007) issued by Saudi Arabian General Investment Authority (SAGIA). We commenced our commercial production on July 1, 2012. During 2015, we received a new mining lease for an area near our current mining area for the Guyan ancient mine. On 16/11/1428 (November 26, 2007), while the Company was in the registration process, the Company signed a contract with China National Geological and Mining Corporation (CGM) for underground mine rehabilitation, pre-production activity, and on-going mine development/production and with Nesma & Partners Contracting Company Limited (Nesma) for engineering, procurement, construction, commissioning and hand over of the concentrator surface works and the related infrastructure facilities. The handover of these facilities was finalized on November 28, 2011. In late 2014, we renegotiated a more favorable plant operations and maintenance contract with CGM. CGM ran our mining operations until November 2015, at which time the Board of Directors cancelled the CGM and Nesma contract and temporarily suspended operations of the Company. See Note 8. This planned, temporary shutdown of the facility was due to the continued depressed commodity price environment as well as needs for renovation and maintenance. Our focus during the renovation focused on improving recoveries overall and upgrading the precious metals circuit through the installation of SART (sulfidization, acidification, recycling, and thickening) modifications which are expected to lower chemical use, thereby reducing operating costs. In February 2016, we entered into a new operating and rehabilitation contract with a different vendor under more favorable terms. We resumed operations in the first quarter of 2017 and generated enough ore for two shipments in 2017. In 2018, we resumed our schedule of 4 shipments a year.

AMAK SUMMARY OF SIGNIFICANT ACC

AMAK SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
AMAK SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Principles of Consolidation – The consolidated financial statements include the balance sheets, statements of income, stockholders' equity, and cash flows of the Company, TOCCO, TC, SHR, GSPL and PEVM. Other entities which are not controlled but over which the Company has the ability to exercise significant influence such as AMAK, are accounted for using the equity method of accounting. All intercompany profits, transactions and balances have been eliminated. Cash, Cash Equivalents and Short-Term Investments – Our principal banking and short-term investing activities are with local and national financial institutions. Short-term investments with an original maturity of three months or less are classified as cash equivalents. Inventories – Finished products and feedstock are recorded at the lower of cost, determined on the first-in, first-out method (FIFO), or market for SHR. For TC, inventory is recorded at the lower of cost or market as follows: (1) raw material cost is calculated using the weighted-average cost method and (2) product inventory cost is calculated using the specific cost method. Trade Receivables and Allowance for Doubtful Accounts – We evaluate the collectability of our trade receivables and adequacy of the allowance for doubtful accounts based upon historical experience and any specific customer financial difficulties of which we become aware. For the year ended December 31, 2018, we increased the balance by $152,000 due to concerns regarding collectability for a specific customer. For the year ended December 31, 2017, the allowance balance was not increased. In 2016, we increased the balance by $90,000 due to an increase in sales in countries where there is a greater risk of default and limited recourse should this occur. We track customer balances and past due amounts to determine if customers may be having financial difficulties. This, along with historical experience and a working knowledge of each customer, helps determine accounts that should be written off. No amounts were written off in 2018 or 2017. During 2016 we wrote off one account for approximately $93,000 . Notes Receivable – We periodically make changes in or expand our custom processing units at the request of the customer. The cost to make these changes is shared by the customer. Upon completion of a project a non-interest note receivable is recorded with an imputed interest rate. There were no notes receivable outstanding as of December 31, 2018. The interest rate used on outstanding notes during December 31, 2018 and 2017 was 4% . The unearned interest was reflected as a discount against the note balance. The Company evaluates the collectability of notes based upon a working knowledge of the customer. The notes are receivable from custom processing customers with whom we maintain a close relationship. Thus, all amounts due under the notes receivable are considered collectible, and no allowance was recorded at December 31, 2018 and 2017 , respectively. Plant, Pipeline and Equipment – Plant, pipeline and equipment are stated at cost. Depreciation is provided over the estimated service lives using the straight-line method. Gains and losses from disposition are included in operations in the period incurred. Maintenance and repairs are expensed as incurred. Major renewals and improvements are capitalized. Interest costs incurred to finance expenditures during construction phase are capitalized as part of the historical cost of constructing the assets. Construction commences with the development of the design and ends when the assets are ready for use. Capitalized interest costs are included in plant, pipeline and equipment and are depreciated over the service life of the related assets. Labor costs incurred to self-construct assets are capitalized as part of the historical cost the assets. Construction commences with the development of the design and ends when the assets are ready for use. Capitalized labor costs are included in plant, pipeline and equipment and are depreciated over the service life of the related assets. Platinum catalyst is included in plant, pipeline and equipment at cost. Amortization of the catalyst is based upon cost less estimated salvage value of the catalyst using the straight line method over the estimated useful life (see Note 8). Goodwill and Other Intangible Assets – Goodwill represents the future economic benefits arising from other assets acquired in the acquisition of TC that are not individually identified and separately recognized. Goodwill and indefinite-lived intangible assets are tested for impairment at least annually; however, these tests are performed more frequently when events or changes in circumstances indicate that the asset may be impaired. Impairment exists when carrying value exceeds fair value. Estimates of fair value are based on appraisals, market prices for comparable assets, or internal estimates of future net cash flows. Definite-lived intangible assets consist of customer relationships, licenses, permits and developed technology that were acquired as part of the Acquisition of TC. The majority of these assets are being amortized using discounted estimated future cash flows over the term of the related agreements. Intangible assets associated with customer relationships are being amortized using the discounted estimated future cash flows method based upon assumed rates of annual customer attrition. We continually evaluate the reasonableness of the useful lives of these assets. Once these assets are fully amortized, they will be removed from the consolidated balance sheets. Business Combinations and Related Business Acquisition Costs – Assets and liabilities associated with business acquisitions are recorded at fair value using the acquisition method of accounting. We allocate the purchase price of acquisitions based upon the fair value of each component which may be derived from various observable and unobservable inputs and assumptions. We may use third-party valuation specialists to assist us in this allocation. Initial purchase price allocations are preliminary and subject to revision within the measurement period, not to exceed one year from the date of acquisition. The fair value of property, plant and equipment and intangible assets are based upon the discounted cash flow method that involves inputs that are not observable in the market (Level 3). Goodwill assigned represents the amount of consideration transferred in excess of the fair value assigned to identifiable assets acquired and liabilities assumed. Business acquisition costs are expensed as incurred and are reported as general and administrative expenses in the consolidated statements of income. We define these costs to include finder's fees, advisory, legal, accounting, valuation, and other professional consulting fees, as well as, travel associated with the evaluation and effort to acquire specific businesses. Investment in AMAK – We account for our investment in AMAK using the equity method of accounting under which we record in income our share of AMAK's income or loss for each period. The amount recorded is also adjusted to reflect the amortization of certain differences between the basis in our investment in AMAK and our share of the net assets of AMAK as reflected in AMAK's financial statements (see Note 10). Any proceeds received from or payments made to AMAK are recorded as decreases or increases in the balance of our investment. We assess our investment in AMAK for impairment when events are identified, or there are changes in circumstances that may have an adverse effect on the fair value of the investment. We consider recoverable ore reserves, changes in commodity prices, and the amount and timing of the cash flows to be generated by the production of those reserves, as well as, recent equity transactions within AMAK. Other Assets – Other assets include a license used in specialty petrochemical operations, spare parts inventory and certain specialty petrochemical assets. Beginning January 1, 2017, due to the expansion of our plant assets at SHR and TC, we began inventorying spare parts for the repair and maintenance of our plant, pipeline and equipment. Spare parts are accounted for on the first-in, first-out method (FIFO). Long-Lived Assets Impairment – Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable based on the undiscounted net cash flows to be generated from the asset's use. The amount of the impairment loss to be recorded is calculated by the excess of the asset's carrying value over its fair value. Fair value is generally determined using a discounted cash flow analysis although other factors including the state of the economy are considered. Revenue Recognition – The Company adopted Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("ASC") Topic 606 ("ASC 606"), Revenue from Contracts with Customers, and its amendments with a date of the initial application of January 1, 2018. As a result, the Company has changed its accounting policy for revenue recognition as detailed below. ASC 606 outlines a single comprehensive model for an entity to use in accounting for revenue arising from all contracts with customers, except where revenues are in scope of another accounting standard. ASC 606 superseded the revenue recognition requirements in ASC Topic 605, " Revenue Recognition", and most industry specific guidance. ASC Topic 606 sets forth a five-step model for determining when and how revenue is recognized. Under the model, an entity is required to recognize revenue to depict the transfer of goods or services to a customer at an amount reflecting the consideration it expects to receive in exchange for those goods and services. ASC 606 also requires certain additional revenue-related disclosures. The Company applied the modified retrospective approach under ASC 606 which allows for the cumulative effect of adopting the new guidance on the date of initial application. Use of the modified retrospective approach means the Company's comparative periods prior to initial application are not restated. The initial application was applied to all contracts at the date of the initial application. The Company has determined that the adjustments using the modified retrospective approach did not have a material impact on the date of the initial application along with the disclosure of the effect on prior periods. Accounting Policy Beginning on January 1, 2018, revenue is measured based on a consideration specified in a contract with a customer. The Company recognizes revenue when it satisfies a performance obligation by transferring control over a product or service to a customer. In evaluating when a customer has control of the asset we primarily consider whether the transfer of legal title and physical delivery has occurred, whether the customer has significant risks and rewards of ownership, and whether the customer has accepted delivery and a right to payment exists. Taxes assessed by a governmental authority that are both imposed on and concurrent with a specific revenue-producing transaction, that are collected by the Company from a customer, are excluded from revenue. Shipping and handling costs associated with outbound freight after control over a product has transferred to a customer are accounted for as a fulfillment cost and are included in cost of product sales and processing. The Company does not offer material rights of return or service-type warranties. For the year ended December 31, 2017 the Company recognized revenue according to FASB ASC Topic 605 ("ASC 605"), " Revenue Recognition" , when: (1) the customer accepted delivery of the product and title had been transferred or when the service was performed and the Company had no significant obligations remaining to be performed; (2) a final understanding as to specific nature and terms of the agreed upon transaction had occurred; (3) price was fixed and determinable; and (4) collection was assured. Product sales generally met these criteria, and revenue was recognized, when the product was delivered or title was transferred to the customer. Sales revenue was presented net of discounts, allowances, and sales taxes. Freight costs billed to customers were recorded as a component of revenue. Revenues received in advance of future sales of products or prior to the performance of services were presented as deferred revenues. Shipping and handling costs were classified as cost of product sales and processing and were expensed as incurred. Nature of goods and services The following is a description of principal activities – separated by reportable segments – from which the Company generates its revenue. For more detailed information about reportable segments, disaggregation of revenues, and contract balance disclosures, see Note 17. Specialty petrochemical segment The specialty petrochemical segment of the Company produces eight high purity hydrocarbons and other petroleum based products including isopentane, normal pentane, isohexane and hexane. These products are used in the production of polyethylene, packaging, polypropylene, expandable polystyrene, poly-iso/urethane foams, crude oil from the Canadian tar sands, and in the catalyst support industry. SHR's specialty petrochemical products are typically transported to customers by rail car, tank truck, iso-container and ship. Product Sales – The Company sells individual (distinct) products to its customers on a stand-alone basis (point-of-sale) without any further integration. There is no significant modification of any one or more products sold to fulfill another promised product or service within any of the Company's product sale transactions. The amount of consideration received for product sales is stated within the executed invoice with the customer. Payment is typically due and collected 30 to 60 days subsequent to point of sale. Processing Fees – The Company's services consist of processing customer supplied feedstocks into custom products including, if requested, services for forming, packaging, and arranging shipping. Pursuant to Tolling Agreements the customer retains title to the feedstocks and processed products. The performance obligation in each Tolling Agreement transaction is the processing of customer provided feedstocks into custom products and is satisfied over time. The amount of consideration received for product sales is stated within the executed invoice with the customer. Payment is typically due and collected within 30 days subsequent to point of sale. Specialty Wax segment The specialty wax segment of the Company manufactures and sells specialty polyethylene and poly alpha olefin waxes and also provides custom processing services for customers. Product Sales – The Company sells individual (distinct) products to its customers on a stand-alone basis (point-of-sale) without any further integration. There is no significant modification of any one or more products sold to fulfill another promised product or service within any of the Company's product sale transactions. The amount of consideration received for product sales is stated within the executed invoice with the customer. Payment is typically due and collected within 30 days subsequent to point of sale. Processing Fees – The Company's promised services consist of processing customer supplied feedstocks into custom products including, if requested, services for forming, packaging, and arranging shipping. Pursuant to Tolling Agreements and Purchase Order Arrangements, the customer typically retains title to the feedstocks and processed products. The performance obligation in each Tolling Agreement transaction and Purchase Order Arrangement is the processing of customer provided feedstocks into custom products and is satisfied over time. The amount of consideration received for product sales is stated within the executed invoice with the customer. Payment is typically due and collected within 30 days subsequent to point of sale. Shipping and Handling Costs – Shipping and handling costs are classified as cost of product sales and processing and are expensed as incurred. Retirement Plan – We offer employees the benefit of participating in a 401(k) plan. We match 100% up to 6% of pay with vesting occurring over 2 years. For years ended December 31, 2018 , 2017 , and 2016 , matching contributions of approximately $1,502,000 , $1,412,000 , and $1,195,000 , respectively were made on behalf of employees. Environmental Liabilities – Remediation costs are accrued based on estimates of known environmental remediation exposure. Ongoing environmental compliance costs, including maintenance and monitoring costs, are expensed as incurred. Other Liabilities – We periodically make changes in or expand our custom processing units at the request of the customer. The cost to make these changes is shared by the customer. Upon completion of a project a note receivable and a deferred liability are recorded to recover the project costs which are then capitalized. At times instead of a note receivable being established, the customer pays an upfront cost. The amortization of other liabilities is recorded as a reduction to depreciation expense over the life of the contract with the customer. As of December 31 of each year, depreciation expense was offset and reduced by approximately $0.8 million , $0.8 million , and $1.0 million , for 2018 , 2017 , and 2016 , respectively. Net Income Per Share – We compute basic income per common share based on the weighted-average number of common shares outstanding. Diluted income per common share is computed based on the weighted-average number of common shares outstanding plus the number of additional common shares that would have been outstanding if potential dilutive common shares, consisting of stock options, unvested restricted stock units, and shares which could be issued upon conversion of debt, had been issued (see Note 18). Foreign Currency – The functional currency for the Company and each of the Company's subsidiaries is the US dollar (USD). Transaction gains or losses as a result of transactions denominated and settled in currencies other than the USD are reflected in the statements of income as foreign exchange transaction gains or losses. We do not employ any practices to minimize foreign currency risks. The functional and reporting currency of AMAK is the Saudi Riyal (SR). In June 1986 the SR was officially pegged to the USD at a fixed exchange rate of 1 USD to 3.75 SR; therefore, we translate SR into our reporting currency of the USD for income statement and balance sheet purposes using the fixed exchange rate. As of December 31, 2018 , 2017 and 2016 , foreign currency translation adjustments were not significant. Management Estimates – The preparation of consolidated financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. Significant estimates include allowance for doubtful accounts receivable and inventory obsolescence; assessment of impairment of our long-lived assets, goodwill, intangible assets and investments, litigation liabilities, post-retirement benefit obligations, guarantee obligations, environmental liabilities, income taxes and deferred tax valuation allowances. Actual results could differ from these estimates. Share-Based Compensation – We recognize share-based compensation of stock options granted based upon the fair value of options on the grant date using the Black-Scholes pricing model (see Note 15). Share-based compensation expense recognized during the period is based on the fair value of the portion of share-based payments awards that is ultimately expected to vest. Share-based compensation expense recognized in the consolidated statements of operations for the years ended December 31, 2018 , 2017 , and 2016 includes compensation expense based on the estimated grant date fair value for awards that are ultimately expected to vest, and accordingly has been reduced for estimated forfeitures. Estimated forfeitures at the time of grant are revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. Guarantees – We may enter into agreements which contain features that meet the definition of a guarantee under FASB ASC 460 "Guarantees" (see Note 14). These arrangements create two types of obligations: a) We have a non-contingent and immediate obligation to stand ready to make payments if certain future triggering events occur. For certain guarantees, a liability is recognized for the stand ready obligation at the inception of the guarantee; and b) We have an obligation to make future payments if those certain future triggering events do occur. A liability for the payment under the guarantee is recognized when 1) it becomes probable that one or more future events will occur, triggering the requirement to make payments under the guarantee and 2) when the payment can be reasonably estimated. Fair Value – The carrying value of cash and cash equivalents, trade receivables, taxes receivable, accounts payable, accrued liabilities, and other liabilities approximate fair value due to the immediate or short-term maturity of these financial instruments. The fair value of variable rate long term debt and notes payable reflect recent market transactions and approximate carrying value. We used other observable inputs that would qualify as Level 2 inputs to make our assessment of the approximate fair value of our cash and cash equivalents, trade receivables, taxes receivable, accounts payable, accrued liabilities, other liabilities, notes payable and variable rate long term debt. The fair value of the derivative instruments are described below. We measure fair value by ASC Topic 820 Fair Value. ASC Topic 820 defines fair value, establishes a framework for measuring fair value, and expands disclosures about fair value measurements. ASC Topic 820 applies to reported balances that are required or permitted to be measured at fair value under existing accounting pronouncements; accordingly, the standard amends numerous accounting pronouncements but does not require any new fair value measurements of reported balances. ASC Topic 820 emphasizes that fair value, among other things, is based on exit price versus entry price, should include assumptions about risk such as nonperformance risk in liability fair values, and is a market-based measurement, not an entity-specific measurement. When considering the assumptions that market participants would use in pricing the asset or liability, ASC Topic 820 establishes a fair value hierarchy that distinguishes between market participant assumptions based on market data obtained from sources independent of the reporting entity (observable inputs that are classified within Levels 1 and 2 of the hierarchy) and the reporting entity's own assumptions about market participant assumptions (unobservable inputs classified within Level 3 of the hierarchy). The fair value hierarchy prioritizes inputs used to measure fair value into three broad levels. In instances where the determination of the fair value measurement is based on inputs from different levels of the fair value hierarchy, the level in the fair value hierarchy within which the entire fair value measurement falls is based on the lowest level input that is significant to the fair value measurement in its entirety. Our assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment and considers factors specific to the asset or liability. Derivatives – We record derivative instruments as either an asset or liability measured at fair value. Changes in the derivative instrument's fair value are recognized currently in earnings unless specific hedge accounting criteria are met. Special accounting for qualifying hedges allows a derivative instrument's gains and losses to offset related results on the hedged item in the income statement, to the extent effective, and requires that a company must formally document, designate and assess the effectiveness of transactions that receive hedge accounting. Income Taxes – Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. The Company maintains a valuation allowance for a deferred tax asset when it is deemed to be more likely than not that some or all of the deferred tax asset will not be realized. Our estimate of the potential outcome of any uncertain tax issues is subject to management's assessment of relevant risks, facts, and circumstances existing at that time. We use a more likely than not threshold for financial statement recognition and measurement of tax position taken or expected to be taken in a tax return. To the extent that our assessment of such tax position changes, the change in estimate is recorded in the period in which the determination is made. We report tax-related interest and penalties as a component of income tax expense. On December 22, 2017, Public Law No. 115-97 known as the Tax Cuts and Jobs Act (TCJA) was enacted. The TCJA included a number of changes to existing U.S. tax laws that impact the Company, most notably a reduction of the U.S. federal corporate income tax rate from a maximum of 35 percent to a flat 21 percent for tax years effective January 1, 2018. The TCJA also implemented a territorial tax system, provided for a one-time deemed repatriation tax on unrepatriated foreign earnings, eliminated the alternative minimum tax (AMT), made AMT credit carryforwards refundable, and permitted the acceleration of depreciation for certain assets placed into service after September 27, 2017. In addition the TJCA created prospective changes beginning in 2018, including repeal of the domestic manufacturing deduction, acceleration of tax revenue recognition, capitalization of research and development expenditures, additional limitations on executive compensation and limitations on the deductibility of interest. The Company has elected to recognize the income tax effects of the TCJA in its financial statements in accordance with Staff Accounting Bulletin 118 (SAB 118), which provides guidance for the application of ASC Topic 740 Income Taxes , in the reporting period in which the TCJA was signed into law. Under SAB 118 when a Company does not have the necessary information available, prepared, or analyzed (including computations) in reasonable detail to complete the accounting for certain income tax effects of the TCJA it will recognize provisional amounts if a reasonable estimate can be made. If a reasonable estimate cannot be made then no impact is recognized for the effect of the TCJA. SAB 118 permits an up to one year measurement period to finalize the measurement of the impact of the TCJA. Reclassifications – Certain reclassifications have been made to prior year balances to conform with the current year presentation. Subsequent Events – The Company has evaluated subsequent events through March 15, 2019 , the date that the consolidated financial statements were approved by management. New Accounting Pronouncements In May 2014 the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2014-9, Revenue from Contracts with Customers ("ASU 2014-9"). ASU 2014-9 supersedes the revenue recognition requirements of FASB Accounting Standards Codification ("ASC") Topic 605, Revenue Recognition and most industry-specific guidance throughout the Accounting Standards Codification, resulting in the creation of FASB ASC Topic 606, Revenue from Contracts with Customers . ASU 2014-9 requires entities to recognize revenue in a way that depicts the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled to in exchange for those goods or services. This ASU provides alternative methods of retrospective adoption and is effective for fiscal years, and interim periods within those years, beginning after December 15, 2017. The Company completed its assessment of the impact of the adoption of ASU 2014-9 across all revenue streams. This included reviewing current accounting policies and practices to identify potential differences that would result from applying the requirements under the new standard. We completed contract reviews and validated results of applying the new revenue guidance (Note 2). See Revenue Recognition policy note. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842). This update will increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. This update is effective for annual and interim reporting periods beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. In July 2018, the FASB issued ASU No. 2018-11, Targeted Improvements to ASC 842, Leases. ASU 2018-11 provided entities with an alternative modified transition method to elect not to recast the comparative periods presented when adopting ASC 842. The new standard provides a number of optional practical expedients in transition. The Company expects to elect: (1) the ‘package of practical expedients’, which permits it not to reassess under the new standard its prior conclusions about lease identification, lease classification, and initial direct costs and (2) the use-of-hindsight. In addition, the new standard provides practical expedients for an entity’s ongoing accounting that the Company anticipates making, such as the (1) the election for certain classes of underlying asset to not separate non-lease components from lease components and (2) the election for short-term lease recognition exemption for all leases that qualify. The Company will adopt ASU 842 as of January 1, 2019, using the alternative modified transition method. In preparation of adopting ASC 842, the Company is implementing additional internal controls to enable future preparation of financial information in accordance with ASC 842. The Company has also substantially completed its evaluation of the impact on the Company’s lease portfolio. The Company believes the largest impact will be on the consolidated balance sheets for the accounting of rail cars, equipment and office leases, which represents a majority of its operating leases it has entered into as a lessee. These leases will be recognized under the new standard as right of use assets (“ROU”) operating lease liabilities. The Company will also be required to provide expanded disclosures for its leasing arrangements. As of December 31, 2018, the Company had approximately $ 18.1 million of undiscounted future minimum operating lease commitments that are not recognized on its consolidated balance sheets as determined under the current standard. For a lessee, the results of operations are not expected to significantly change after adoption of the new standard. While substantially complete, the Company is still in the process of finalizing its evaluation of the effect of ASU 842 on the Company’s financial statements and disclosures, including the determination of the Company’s incremental borrowing rate for each of the operating leases to estimate the interest rate we would have to pay to borrow on a collateralized basis over a similar term for an amount equal to the lease payments. The Company will finalize its accounting assessment and quantitative impact of the adoption during the first quarter of fiscal year 2019. In January 2017 the FASB issued ASU No. 2017-4, Intangibles – Goodwill and Other (Topic 350) . The amendments in ASU 2017-4 simplify the measurement of goodwill
AMAK
Schedule of Equity Method Investments [Line Items]
AMAK SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	Summary of Significant Accounting Policies The accompanying financial statements have been prepared using U.S. generally accepted accounting principles. The following is a summary of our significant accounting policies: Cash and cash equivalents We consider all highly-liquid investments purchased with an original maturity of three months or less to be cash equivalents. Accounts receivable We evaluate the collectability of our accounts receivable and the adequacy of the allowance for doubtful accounts based upon historical experience and any specific customer financial difficulties of which the Company becomes aware. During the years ended December 31, 2018, 2017, and 2016, we sold our concentrates and doré pursuant to a sales contract with one customer. No amounts have been written off for the years ended December 31, 2018, 2017, and 2016. In addition, we determined that an allowance for doubtful accounts was not necessary at December 31, 2018 and 2017. Inventories The components of inventories include mill stockpiles, precious metal doré, chemicals, and mining supplies. Inventories are stated at the lower of weighted-average cost or market. Costs of mill stockpiles inventory include labor and benefits, supplies, energy, depreciation, depletion, amortization, and other necessary costs incurred with the extraction and processing of ore. Corporate general and administrative costs are not included in inventory costs. Because it is generally impracticable to determine the minerals contained in mill stockpiles by physical count, reasonable estimation methods are employed. The quantity of material delivered to the mill stockpiles is based on surveyed volumes of mined material and daily production records. Expected mineral recovery rates from the mill stockpiles are determined by various metallurgical testing methods. Property and equipment Property and equipment is carried at cost less accumulated depreciation. Expenditures for replacements and improvements are capitalized. Costs related to periodic maintenance are expensed as incurred. Depletion of the mining assets is determined using the unit-of-production method based on total estimated proven and probable reserves. Depletion and amortization using the unit-of-production method is recorded upon extraction of the ore, at which time it is allocated to inventory cost and then included as a component of cost of goods sold. Other assets are depreciated on a straight-line basis over their estimated useful lives ranging from 3 to 20 years. Borrowing costs that are directly attributable to the acquisition, construction or production of assets are capitalized as part of the cost of those assets. Assets under construction are capitalized in the construction in progress account. Upon completion, the cost of the related asset is transferred to the appropriate category of property and equipment. Development costs Mineral exploration costs, as well as drilling and other costs incurred for the purpose of converting mineral resources to proven and probable reserves or identifying new mineral resources are charged to expense as incurred. Development costs are capitalized beginning after proven and probable reserves have been established. Development costs include costs incurred in mine pre-production activities undertaken to gain access to proven and probable reserves, including shafts, drifts, ramps, permanent excavations, infrastructure and removal of overburden. These costs are deferred net of the proceeds from the sale of any production during the development period and then amortized using an estimated unit-of-production method. If a mine is no longer considered economical, the accumulated costs are charged to the statement of operations in the year in which the determination is made. Asset impairment We review and evaluate our long-lived assets for impairment when events or changes in circumstances indicate that the carrying amounts may not be recoverable. Long-lived assets are evaluated for impairment under the two-step model. When events or circumstance suggest impairment of long-lived assets, estimated undiscounted future net cash flows are calculated using future estimated commodity prices, proven and probable reserves, and estimated net proceeds from the disposition of assets on retirement, less operating, sustaining capital, and reclamation costs. If it is determined that an impairment exists, an impairment loss is measured as the amount by which the asset carrying value exceeds its fair value. Fair value is generally determined using valuation techniques such as estimated future cash flows. Because the cash flows used to assess recoverability of our long-lived assets and measure fair value of our mining operations require us to make several estimates and assumptions that are subject to risk and uncertainty, changes in these estimates and assumptions could result in the impairment of our long-lived asset values. Based on our evaluation, we recorded no impairment losses during the years ended December 31, 2018, 2017 and 2016. End-of-service indemnities Employee end-of-service benefits are accrued for the benefit of employees under the terms and conditions of Saudi Labor Law and Regulations and their employment contracts. End-of-service indemnities are provided for and accrued in the financial statements based on the respective employees' salaries and length of service. Pre-export Advances At times we receive advances on a pre-export basis against a portion of our inventory on hand prior to shipment. These advances bear interest at 2.5% and are repaid from the proceeds from final concentrate sales. We did not have an outstanding advance liability at December 31, 2018 and 2017. Foreign currency Our functional currency is the Saudi Riyal (SR). In June 1986, the Saudi Riyal was officially pegged to the U.S. Dollar at a fixed exchange rate of 1 U.S. Dollar to 3.75 riyals. Foreign currency transactions are translated into Saudi Riyals at the rates of exchange prevailing at the time of the transactions. Monetary assets and liabilities denominated in foreign currencies at the balance sheet date are translated at the exchange rates prevailing at that date. Any gains and losses from settlement and translation of foreign currency transactions are included in the statement of operations. There were no material foreign-currency exchange gains or losses or translation adjustments during the years ended December 31, 2018, 2017, and 2016. Leasing arrangements We periodically lease operating equipment, facilities, and office buildings. Rentals payable under operating leases are charged to the statements of operations on a straight-line basis over the term of the relevant lease. For any capital leases, the present value of future minimum lease payments at the inception of the lease is reflected as an asset and a liability in the balance sheet. Amounts due within one year are classified as short-term liabilities and the remaining balance as long-term liabilities. Finance charges are charged to the statement of operations. Operating lease expense amounted to approximately SR 1,619,000 , SR 1,454,000 and SR 442,000 for the years ended December 31, 2018, 2017 and 2016, respectively. Environmental costs Environmental costs are expensed or capitalized, depending upon their future economic benefits. Accruals for such expenditures are recorded when it is probable that obligations have been incurred and the costs can reasonably be estimated. Ongoing compliance costs are expensed as incurred. Asset retirement obligations and costs We record the fair value of our estimated asset retirement obligations (AROs) associated with tangible long-lived assets in the period in which the obligation is incurred. AROs associated with long-lived assets are those for which there is a legal obligation to settle under various laws, statues, or regulations. These obligations, which are initially estimated based on discounted cash flow estimates, are accreted to full value over time through charges to cost of revenues. In addition, asset retirement costs (ARCs) are capitalized as part of the related asset’s carrying value and are depreciated (primarily on a unit-of-production basis) over the asset’s respective useful life. Our AROs consist primarily of costs associated with mine reclamation and closure activities and are included in deferred mine closure costs on the accompanying balance sheets. At least annually, we review our ARO estimates for changes in the projected timing and changes in cost estimates and additional AROs incurred during the period. Zakat and income tax We are subject to the Regulations of the General Authority of Zakat and Tax (GAZT) in the Kingdom of Saudi Arabia. Under these regulations, Zakat is payable at 2.5% on the basis of the portion of our Zakat base attributable to our Saudi stockholders, and income tax is payable at 20% on the portion of our taxable income attributable to our non-Saudi stockholders. Zakat and income tax are provided on an accrual basis. Any difference in the estimate is recorded when the final assessment is approved, at which time the provision is cleared. We account for deferred income taxes on non-Saudi owners utilizing an asset and liability method, whereby deferred tax assets and liabilities are recognized based on the tax effects of temporary differences between the financial statements and the income tax basis of assets and liabilities, as measured by the effective tax rate. When appropriate, we evaluate the need for a valuation allowance based on a more likely than not threshold to reduce deferred tax assets to estimated recoverable amounts. We account for uncertain income tax positions using a threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. We report tax-related interest and penalties as a component of Zakat and income tax expense. We recognized no material adjustment for unrecognized income tax liabilities. Zakat and income tax returns for the years from 2010 to 2017 are currently under review with GAZT. Reclassifications Certain reclassifications have been made to the prior periods to conform with current year presentation. Revenue recognition We sell our products pursuant to sales contracts entered into with a customer who acts as an intermediary and resells our products to end users. Revenue is recognized when title and risk of loss pass to the customer and when collectability is reasonably assured. The passing of title and risk of loss to the customer is based on terms of the sales contract, generally upon shipment or delivery of product. Sales are recorded based on a provisional sales price or a final sales price calculated in accordance with the terms specified in the relevant sales contract. Under the long-established structure of sales agreements prevalent in the industry, the copper and zinc contained in concentrate is generally provisionally priced at the time of shipment. The provisional price received at the time of shipment is later adjusted to a final price based on quoted monthly average spot prices on the London Metal Exchange (LME) for a specified future month. We record revenues at the time of shipment (when title and risk of loss pass) based on then-current LME prices, and we account for any changes between the sales price recorded at the time of shipment and subsequent changes in the LME prices through the date of final pricing as gains or losses from a derivative embedded in the sales contract (a futures contract initiated at the date of shipment and settled upon the determination of the final price) which is bifurcated and separately accounted for at fair value. See Note 16. Revenues from concentrate sales are recorded net of treatment and refining charges. These allowances are a negotiated term of each contract. Treatment and refining charges represent payments or price adjustments to smelters and refiners and are either fixed, or in certain cases, vary with the price of metals (referred to as price participation). Management estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting periods. The most significant areas requiring the use of management estimates include mineral reserve estimation; useful asset lives for depreciation and amortization; zakat and income taxes; environmental obligations; reclamation and closure costs; estimates of recoverable materials in mill stockpiles; fair value of embedded derivatives; end-of-service indemnities; and asset impairment, including estimates used to derive future cash flows associated with those assets. Actual results could differ from these estimates. Recent accounting pronouncements In May 2014 the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2014-09, Revenue from Contracts with Customers ("ASU 2014-09"). ASU 2014-09 supersedes the revenue recognition requirements of FASB Accounting Standards Codification ("ASC") Topic 605, Revenue Recognition and most industry-specific guidance throughout the Accounting Standards Codification, resulting in the creation of FASB ASC Topic 606, Revenue from Contracts with Customers. ASU 2014-09 requires entities to recognize revenue in a way that depicts the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled to in exchange for those goods or services. For nonpublic companies this ASU provides alternative methods of retrospective adoption and is effective for fiscal years and interim periods beginning after December 15, 2018. Early adoption is permitted. The Company is evaluating the impact of these amendments, although it does not expect the amendments to have a significant impact to the Company’s financial position or results of operation. In February 2016 the FASB issued ASU No. 2016-02, Leases (Topic 842), to increase transparency and comparability among organizations by recognizing all lease transactions (with terms in excess of 12 months) on the balance sheet as a lease liability and a right-of-use asset (as defined). The ASU is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, with earlier application permitted. Upon adoption, the lessee will apply the new standard retrospectively to all periods presented or retrospectively using a cumulative effect adjustment in the year of adoption. The Company has several lease agreements for which the amendments will require the Company to recognize a lease liability to make lease payments and a right-of-use asset which will represent its right to use the underlying asset for the lease term. As permitted by the amendments, the Company is anticipating electing an accounting policy to not recognize lease assets and lease liabilities for leases with a term of twelve months or less. The Company is currently reviewing the amendments to ensure it is fully compliant by the adoption date and does not expect to early adopt. In addition, the Company will change its current accounting policies to comply with the amendments with such changes as mentioned above. Subsequent events We have evaluated events and transactions subsequent to the date of the financial statements for matters requiring recognition or disclosure in the financial statements. The accompanying financial statements consider events through March 6, 2019, the date on which the financial statements were available to be issued.

AMAK LIQUIDITY AND CAPITAL RESO

AMAK LIQUIDITY AND CAPITAL RESOURCES	12 Months Ended
	Dec. 31, 2018
AMAK
Schedule of Equity Method Investments [Line Items]
LIQUIDITY AND CAPITAL RESOURCES	Liquidity and Capital Resources As shown in the financial statements, we have incurred three consecutive years of net losses however, the Company resumed full operations and had operating income and cash provided from operations during the year ended December 31, 2018. In addition, we expect to update our mineral resources and life of mine in 2019 with the expectation that the life of mine will be extended another two years. We believe that our continued operations and the adjusted repayment terms of our outstanding debt will provide us the necessary liquidity and capital resources.

AMAK INVENTORIES

AMAK INVENTORIES	12 Months Ended
	Dec. 31, 2018
Inventory [Line Items]
INVENTORIES	INVENTORIES Inventories include the following at December 31: 2018 2017 (thousands of dollars) Raw material $ 4,742 $ 3,703 Work in process 173 27 Finished products 11,624 14,720 Total inventory $ 16,539 $ 18,450 Inventory serves as collateral for our amended and restated loan agreement with a domestic bank (see Note 12). Inventory included products in transit valued at approximately $4.1 million and $3.7 million at December 31, 2018 , and 2017 , respectively.
AMAK
Inventory [Line Items]
INVENTORIES	Inventories Inventories consisted of the following at: December 31, 2018 2017 Ore concentrates 17,020,657 12,118,132 Stockpile ore 19,134,297 9,417,626 Precious metal dore 2,159,192 — Explosives 1,134,728 485,668 Chemicals and other 6,422,246 5,205,506 45,871,120 27,226,932 As discussed in Note 2, we can receive advances on a pre-export basis on our mill stockpiles.

AMAK ADVANCES TO CONTRACTORS AN

AMAK ADVANCES TO CONTRACTORS AND OTHER	12 Months Ended
	Dec. 31, 2018
AMAK
Schedule of Equity Method Investments [Line Items]
ADVANCES TO CONTRACTORS AND OTHER	Advances to Contractors and Other Advances to contractors and other consisted of the following at: December 31, 2018 2017 Advances to contractors 15,127,502 11,992,870 Prepaid expenses 1,196,218 4,385,449 Other miscellaneous advances and receivables 2,845,045 3,353,461 19,168,765 19,731,780

AMAK PROPERTY AND EQUIPMENT

AMAK PROPERTY AND EQUIPMENT	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
PROPERTY AND EQUIPMENT	PLANT, PIPELINE AND EQUIPMENT Plant, pipeline and equipment include the following at December 31: 2018 2017 (thousands of dollars) Platinum catalyst $ 1,612 $ 1,612 Catalyst 3,131 779 Land 5,428 5,428 Plant, pipeline and equipment 253,905 186,946 Construction in progress 4,343 50,996 Total plant, pipeline and equipment 268,419 245,761 Less accumulated depreciation (73,762 ) (63,240 ) Net plant, pipeline and equipment $ 194,657 $ 182,521 Plant, pipeline and equipment serve as collateral for our amended and restated loan agreement with a domestic bank (see Note 12). Interest capitalized for construction for 2018 , 2017 and 2016 was approximately $731,000 , $937,000 and $450,000 , respectively. Labor capitalized for construction for 2018 , 2017 and 2016 was approximately $2,307,000 , $4,344,000 and $2,889,000 , respectively. Catalyst amortization relating to the platinum catalyst which is included in cost of sales was approximately $59,000 , $25,000 and $98,000 for 2018 , 2017 and 2016 , respectively.
AMAK
Property, Plant and Equipment [Line Items]
PROPERTY AND EQUIPMENT	Property and Equipment Property and equipment, net consisted of the following at: December 31, 2018 2017 Buildings 191,041,157 191,041,157 Leasehold improvements 1,838,317 1,838,317 Heavy equipment 118,125,568 110,259,122 Motor vehicles 22,467,300 22,783,108 Civil works 15,662,671 15,582,921 Tailings dam 23,042,594 22,684,394 Plant and machinery 324,372,695 315,029,454 Mining assets – rehabilitation costs 98,894,826 98,894,826 Mining assets – underground development costs 267,128,896 254,832,012 Construction in progress 5,106,409 5,532,817 1,067,680,433 1,038,478,128 Less accumulated depreciation, depletion and amortization (432,824,358 ) (344,676,457 ) 634,856,075 693,801,671 Property and equipment serve as collateral for the SIDF loan agreement (see Note 10). Depreciation, depletion and amortization expense related to property and equipment was approximately, SR 88,000,000 and SR 64,300,000 for years ended December 31, 2018 and 2017. During 2016, the mine was temporarily closed for renovation, therefore, no amortization or depletion was recorded on certain mining assets.

AMAK DEVELOPMENT COSTS

AMAK DEVELOPMENT COSTS	12 Months Ended
	Dec. 31, 2018
AMAK
Schedule of Equity Method Investments [Line Items]
DEVELOPMENT COSTS	Development Costs Development costs, net consisted of the following at: December 31, 2018 2017 Cost 289,973,237 289,973,237 Accumulated amortization (134,691,712 ) (98,445,057 ) 155,281,525 191,528,180 Development costs are amortized using the unit of production method upon extraction of the ore. Amortization expenses related to development costs was approximately SR 36,250,000 and SR 18,200,000 for the year ended December 31, 2018 and 2017, respectively.

AMAK ACCOUNTS PAYABLE, ACCRUED

AMAK ACCOUNTS PAYABLE, ACCRUED LIABILITIES AND FORGIVENESS OF LIABILITIES	12 Months Ended
	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
ACCOUNTS PAYABLE, ACCRUED LIABILITIES AND FORGIVENESS OF LIABILITIES	ACCRUED LIABILITIES Accrued liabilities at December 31 are summarized as follows: 2018 2017 (thousands of dollars) Accrued state taxes $ 210 $ 272 Accrued payroll 936 1,407 Accrued interest 31 30 Accrued officer compensation — 500 Accrued restructuring & severance expenses (Note 21) 1,221 — Accrued foreign taxes 802 — Other liabilities 2,239 1,752 Total $ 5,439 $ 3,961
AMAK
Schedule of Equity Method Investments [Line Items]
ACCOUNTS PAYABLE, ACCRUED LIABILITIES AND FORGIVENESS OF LIABILITIES	Accounts Payable, Accrued Liabilities and Forgiveness of Liabilities Accounts payable and accrued liabilities consisted of the following at: December 31, 2018 2017 Accounts payable and accrued liabilities 26,925,170 17,858,012 Other 381,763 2,802,493 Accrued salaries and payroll expenses 1,450,012 2,012,113 28,756,945 22,672,618 On March 31, 2016, the Company entered into finalization and discharge memorandums of understanding (MOU’s) with their former mine operator CGM and subcontractor Nesma where certain contracts were cancelled. These contracts included the EPC Surface Works Contract and Subcontract (CGM/NESMA) dated November 26, 2007, the Underground Mining Contract (CGM) dated June 29, 2010, the 1st Surface Works O&M Contract (CGM) dated July 3, 2011, and the 2nd Surface Works O&M Contract (CGM) dated November 3, 2014 (collectively, the Contracts). The MOU’s were binding agreements between the Company, CGM and Nesma. All of CGM’s spare parts on site related to the Contracts reverted to and became the property of the Company. CGM received payment of approximately SR 4,500,000 and forfeited their rights to the spare parts that had an economic value of approximately SR 34,477,500 . The spare parts were recorded at SR 4,500,000 and were included in property and equipment, net on the balance sheets. Under the MoU’s, CGM and Nesma did not receive any further payments from the Company as full settlement against the deterioration of property, plant and equipment which exceeded normal wear and tear and any other breach of contracts. In recognition of certain financial losses incurred by the Company, CGM and NESMA forfeited the recovery of all remaining amounts due under the Contracts. The total amounts of liabilities recorded on the Company’s books as of March 31, 2016 were approximately SR 65,345,000 which were written off to other income on the statement of operations for the year ended December 31, 2016. There were no outstanding or unresolved claims and all parties have fulfilled their obligations in connection with the Contracts.

AMAK ZAKAT AND INCOME TAX

AMAK ZAKAT AND INCOME TAX	12 Months Ended
	Dec. 31, 2018
Income Tax Contingency [Line Items]
ZAKAT AND INCOME TAX	INCOME TAXES The provision for income taxes consisted of the following: Year ended December 31, 2018 2017 2016 (thousands of dollars) Current federal provision (benefit) $ (74 ) $ (1,202 ) $ 1,691 Current state provision 31 282 18 Deferred federal provision (benefit) (974 ) (6,320 ) 8,645 Deferred state provision 210 81 150 Income tax expense (benefit) $ (807 ) $ (7,159 ) $ 10,504 In connection with the AMAK share repurchase discussed in Note 10, the Company anticipates a Saudi Arabian income tax liability of approximately $802,000 . This amount is included in accrued liabilities and will be paid once the transaction is complete. We had no Saudi Arabian income tax expense or liability in 2017 or 2016 . The difference between the effective tax rate in income tax expense and the Federal statutory rate of 21% for the year ended December 31, 2018 , and 35% for the years ended December 31 2017 and 2016 , is as follows: 2018 2017 2016 (thousands of dollars) Income taxes at U.S. statutory rate $ (822 ) $ 3,885 $ 10,476 State taxes, net of federal benefit 234 235 285 Net operating loss carryback — (961 ) — Research and development credits (263 ) — — Permanent and other items 44 (11 ) (257 ) Deferred tax impact of US tax reform — (10,307 ) — Total tax expense (benefit) $ (807 ) $ (7,159 ) $ 10,504 Permanent differences are primarily due to the Federal manufacturer's deduction, research and development credit, and stock based compensation. The Company has recognized the provisional tax impacts related to the acceleration of depreciation and included these amounts in its consolidated financial statements for the year ended December 31, 2018 . After the analysis, the Company did not identify items for which the income tax effects of the TCJA have not been completed and a reasonable estimate could not be determined as of December 31, 2018 . The changes to existing U.S. tax laws as a result of the TCJA, which will have the most significant impact on the Company's federal income taxes are as follows: Reduction of the U.S. Corporate Income Tax Rate - The Company uses the asset and liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to reverse. As a result of the reduction in the U.S. corporate income tax rate from 35% to 21% under the TCJA, the Company revalued its ending net deferred tax liabilities at December 31, 2017 . Acceleration of Depreciation - The Company recognized a provisional reduction to net deferred tax assets attributable to the accelerated depreciation for certain assets placed into service after September 27, 2017. The provisional estimate was finalized including consideration of TCJA on long term construction projects. Tax effects of temporary differences that give rise to significant portions of federal and state deferred tax assets and deferred tax liabilities were as follows: December 31, 2018 2017 (thousands of dollars) Deferred tax liabilities: Plant, pipeline and equipment $ (25,169 ) $ (17,014 ) Intangible assets (1,075 ) (778 ) Other assets (40 ) (4 ) Investment in AMAK (671 ) (1,023 ) Total deferred tax liabilities $ (26,955 ) $ (18,819 ) Deferred tax assets: Accounts receivable 238 198 Inventory 133 156 Mineral interests 226 226 Foreign tax credit 802 — Net operating loss carryforward 9,073 — Post-retirement benefits 79 252 Stock-based compensation 954 971 Gross deferred tax assets 11,505 1,803 Valuation allowance (226 ) (226 ) Total net deferred tax assets $ 11,279 $ 1,577 Net deferred tax liabilities $ (15,676 ) $ (17,242 ) In connection with the proceeds received from AMAK in connection with its share repurchase program, the Company accrued a deferred tax asset (foreign tax credit) and the corresponding liability for the anticipated Saudi Arabian tax. We provided a valuation allowance in 2018 and 2017 against certain deferred tax assets because of uncertainties regarding their realization. There was no change in the valuation allowance for 2018 or 2017 . We file an income tax return in the U.S. federal jurisdiction and a margin tax return in Texas. We received notification from the Internal Revenue Service ("IRS") in November 2016 on the selection of the December 31, 2014 tax return for audit. The IRS expanded its audit to include the Research and Development ("R&D") Credits for the year ended December 31, 2015. The IRS closed its audit without change in March 2018. We also received notification that Texas will audit our R&D credit calculations for 2014 and 2015. The state of Texas has suspended the audit of the Company's R&D credit. Texas is comprehensively reviewing their audit procedures for consistency. We do not expect any changes related to the Texas audits. Our federal and Texas tax returns remain open for examination for the years 2015 through 2018. We recognized no adjustment for uncertain tax positions. As of December 31, 2018 , and 2017 , no interest or penalties related to uncertain tax positions had been accrued.
AMAK
Income Tax Contingency [Line Items]
ZAKAT AND INCOME TAX	Zakat and Income Tax We have submitted our Zakat and income tax return for the year ended December 31, 2017 and have obtained our 2017 Zakat certificate. We are in the process of preparing and submitting our Zakat and income tax return for the year 2018. The Zakat base for the Saudi shareholders was positive in 2018, 2017 and 2016 and the corresponding Zakat expense and liability has been recorded. There was a taxable profit attributable to our non–Saudi (foreign) shareholders in 2018 and the current income tax expense and liability has also been recorded. There was no taxable profit attributable to our non-Saudi (foreign) shareholders for 2017 and 2016, therefore, no current income tax liability is due in those years. The components of Zakat and income tax benefit (expense) are as follows: Years ended December 31, 2018 2017 2016 Deferred income tax benefit 12,961,569 8,617,706 6,694,909 Change in valuation allowance (5,736,640 ) (9,035,670 ) (8,413,167 ) Current Zakat and income tax expense (5,400,000 ) (3,209,229 ) (1,877,986 ) Zakat and income tax benefit (expense) 1,824,929 (3,627,193 ) (3,596,244 ) The difference between the effective income tax rate and the statutory rate for non-Saudi shareholders of 20% for the years ended December 31, 2018, 2017, and 2016, relates to changes in the valuation allowance and adjustments to estimates in depreciation. Tax effects of temporary differences that give rise to significant portions of non-Saudi owners deferred tax assets and deferred tax liabilities were as follows: December 31, 2018 2017 Deferred tax assets: Loss carryforward 42,194 42,884 Other 657 469 42,851 43,352 Deferred tax liabilities: Property and Equipment (7,806 ) (21,236 ) Net deferred tax asset 35,045 22,116 Valuation allowance (38,837 ) (33,134 ) Net deferred tax liability (3,793 ) (11,018 ) At December 31, 2018 and 2017, we had tax loss carryforwards totaling approximately SR 210,970,000 and SR 214,418,000 . Tax losses may be carried forward indefinitely subject to certain annual limitations for non-Saudi shareholders. We have provided a valuation allowance in 2018 and 2017 against a portion of our gross deferred tax assets because of uncertainties regarding their realization.

AMAK LONG-TERM DEBT

AMAK LONG-TERM DEBT	12 Months Ended
	Dec. 31, 2018
AMAK
Debt Instrument [Line Items]
LONG-TERM DEBT	Long-term Debt During 2010, the Company entered into a loan agreement with the Saudi Industrial Development Fund (SIDF) for SR 330,000,000 to finish the development of the mine and provide working capital. The loan originally matured in 2019, however, the agreement was amended during 2015 to adjust the maturity date to 2022 as well as the repayment schedule. We did not make certain scheduled loan repayments due in 2017 and 2018 and engaged with SIDF to renegotiate the terms of the debt. In July 2018, we amended our agreement with SIDF to adjust the repayment schedule and extend the maturity date to 2024. Under the terms of the agreement with SIDF, we are required to maintain certain financial covenants, among other requirements. The loan agreement is collateralized by all the assets of Company and is guaranteed by the shareholders. Long-term debts are summarized as follows at: December 31, 2018 2017 SIDF loan agreement 305,000,000 305,000,000 Deferred finance charges (8,741,288 ) (10,917,190 ) Total debt 296,258,712 294,082,810 Less current portion 30,000,000 65,000,000 Total long-term debt, less current portion 266,258,712 229,082,810 Deferred finance costs are comprised of SIDF loan origination charges which are capitalized and amortized over the period of the related loan which approximates the interest method. Loan fees of SR 8,741,288 and SR 10,917,190 net of accumulated amortization are included net with long-term debt at December 31, 2018 and 2017. Amortization of loan fees amounted to approximately SR 1,639,000 , SR 1,611,000 , and SR 2,148,000 for the years ended December 31, 2018, 2017, and 2016, respectively. The repayment schedule is as follows: Years Ending December 31, 2019 30,000,000 2020 50,000,000 2021 60,000,000 2022 60,000,000 2023 70,000,000 Thereafter 35,000,000 305,000,000

AMAK END-OF-SERVICE INDEMNITIES

AMAK END-OF-SERVICE INDEMNITIES	12 Months Ended
	Dec. 31, 2018
AMAK
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
END-OF-SERVICE INDEMNITIES	End-of-Service Indemnities The change in the end-of-service indemnities provision is as follows: Years Ended December 31, 2018 2017 Balance, beginning of year 2,518,529 1,480,636 Provision for the year 1,347,418 1,375,024 Paid during the year (216,058 ) (337,131 ) Balance, end of year 3,649,889 2,518,529

AMAK ASSET RETIREMENT OBLIGATIO

AMAK ASSET RETIREMENT OBLIGATIONS	12 Months Ended
	Dec. 31, 2018
AMAK
Schedule of Equity Method Investments [Line Items]
ASSET RETIREMENT OBLIGATIONS	Asset Retirement Obligations During 2012, we recorded an ARO for deferred mine closure costs of approximately SR 12,843,000 . These deferred mine closure costs are being amortized over the estimated life of the mine. Amortization expense was approximately SR 745,000 , SR 1,117,000 , and SR 1,117,000 for the years ended December 31, 2018, 2017, and 2016. Deferred mine closure costs consisted of the following at: December 31, 2018 2017 Cost 12,842,625 12,842,625 Accumulated amortization (6,886,626 ) (6,142,126 ) 5,955,999 6,700,499 A summary of changes in our provision for mine closure costs is as follows: Years Ended December 31, 2018 2017 2016 Balance, beginning of year 15,519,938 14,995,109 14,488,028 Accretion expense 543,198 524,829 507,081 Balance, end of year 16,063,136 15,519,938 14,995,109 ARO costs may increase or decrease significantly in the future as a result of changes in regulations, changes in engineering designs and technology, permit modifications or updates, changes in mine plans, inflation or other factors and as actual reclamation spending occurs.

AMAK GENERAL AND ADMINISTRATIVE

AMAK GENERAL AND ADMINISTRATIVE EXPENSES	12 Months Ended
	Dec. 31, 2018
AMAK
Schedule of Equity Method Investments [Line Items]
GENERAL AND ADMINISTRATIVE EXPENSES	General and Administrative Expenses A summary of general and administrative expenses is as follows: Years Ended December 31, 2018 2017 2016 Wages, salaries and related costs 17,036,965 14,837,901 10,195,511 Mine closure and environmental 1,287,698 1,641,580 1,623,831 Office expenses 9,287,218 6,589,090 5,491,679 Travel and accommodation 593,046 2,958,938 1,477,413 Professional fees 1,271,071 2,272,224 8,169,121 29,475,998 28,299,733 26,957,555

AMAK COMMITMENTS AND CONTINGENC

AMAK COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2018
Loss Contingencies [Line Items]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Guarantees On October 24, 2010, we executed a limited guarantee in favor of the Saudi Industrial Development Fund ("SIDF") whereby we agreed to guaranty up to 41% of the SIDF loan to AMAK in the principal amount of 330.0 million Saudi Riyals (US $88.0 million ) (the "Loan"). The term of the loan is currently through June 2022. As a condition of the Loan, SIDF required all shareholders of AMAK to execute personal or corporate guarantees; as a result, the Company's guarantee is for approximately 135.3 million Saudi Riyals (US $36.1 million ). The loan was necessary to continue construction of the AMAK facilities and provide working capital needs. Our current assessment is that the probability of contingent performance is remote based on our analysis of the contingent portion of the guarantee which included but was not limited to the following: (1) the SIDF has historically not called guarantees, (2) the value of the assets exceeds the amount of the loan (3) the other shareholders have indicated that they would prioritize their personal guarantees ahead of the corporate guarantee, and (4) according to Saudi Arabian legal counsel, assets outside of Saudi Arabia are protected from the Saudi Court System. We received no consideration in connection with extending the guarantee and did so to maintain and enhance the value of our investment. Our non-contingent and immediate obligation to stand ready to make payments if the events of default under the guarantee occur was not material to the financial statements. The total amount outstanding to the SIDF at December 31, 2018 , and 2017 was 305.0 million and 305.0 million Saudi Riyals (US $81.3 million and $81.3 million ), respectively. Operating Lease Commitments We have operating leases for the rental of approximately 346 railcars for shipping purposes with expiration dates through 2026 . Invoices are received and paid on a monthly basis. The total amount of the commitment is approximately $17.3 million over the next 9 years. We also have an operating lease for our office space in Sugar Land, Texas. The expiration date for this lease is September 2023 . The total amount of the commitment is approximately $587,000 . In addition, we are required to make periodic payments for property taxes, utilities and common area operating expenses. In addition, we have operating leases for other equipment such as forklifts and copiers with varying expiration dates through 2023 . These commitments are approximately $207,000 . Future minimum property and equipment lease payments under the non-cancelable operating leases at December 31, 2018 , are as follows: Year Ending December 31, (thousands of dollars) 2019 $ 3,670 2020 3,583 2021 3,418 2022 3,107 2023 2,288 Thereafter 2,065 Total $ 18,131 Rental expense for these operating leases for the years ended December 31, 2018 , 2017 , and 2016 was $4.4 million , $4.4 million and $4.2 million , respectively. Litigation From time to time, we may become party to litigation or other legal proceedings that we consider to be a part of the ordinary course of our business. We are not currently involved in any legal proceedings that we believe could reasonably be expected to have a material adverse effect on our business, prospects, financial condition or results of operations. We may become involved in material legal proceedings in the future. On March 21, 2011, Mr. El Khalidi filed suit against the Company in Texas alleging breach of contract and other claims. The 88th Judicial District Court of Hardin County, Texas dismissed all claims and counterclaims for want of prosecution in this matter on July 24, 2013. The Ninth Court of Appeals subsequently affirmed the dismissal for want of prosecution and the Supreme Court of Texas denied Mr. El Khalidi's petition for review. On May 1, 2014, Mr. El Khalidi refiled his lawsuit against the Company for breach of contract and defamation in the 356th Judicial District Court of Hardin County, Texas. The case was transferred to the 88th Judicial District Court of Hardin County, Texas. The Trial Court dismissed all of Mr. El Khalidi's claims and causes of action with prejudice and the Ninth Court of Appeals affirmed. Mr. El Khalidi filed a petition for review with the Supreme Court of Texas, which was denied April 6, 2018. Mr. El Khalidi filed a motion for rehearing of his petition for review with the Supreme Court of Texas on April 23, 2018. On May 25, 2018, the Supreme Court of Texas denied the motion for rehearing and the matter is considered closed. Supplier Agreements From time to time, we may incur shortfall fees due to feedstock purchases being below the minimum amounts as prescribed by our agreements with our suppliers. The shortfall fee expenses were not significant for the years ended December 31, 2018 , 2017 , and 2016 . Environmental Remediation Amounts charged to expense for various activities related to environmental monitoring, compliance, and improvements were approximately $745,000 in 2018 , $593,000 in 2017 and $622,000 in 2016 .
AMAK
Loss Contingencies [Line Items]
COMMITMENTS AND CONTINGENCIES	Commitments and Contingencies Operating lease obligations Our lease commitment for our surface mining lease was initially granted for a period of 30 years through 2024. The lease allows for renewal for an additional 20 years. We also have leases for our corporate offices and three residential villas in Najran through 2025. There is also a mining lease that covers the Guyan area for a period of 20 years. A summary of these commitments are as follows: Years Ending December 31, 2019 990,000 2020 990,000 2021 990,000 2022 990,000 2023 550,000 Thereafter 1,650,000 6,160,000 Capital lease obligations We lease certain equipment vehicles under capital lease obligations that are set to expire at various dates through 2021. The future minimum lease payments under the capital lease obligations are as follows for the years ending December 31,: 2019 250,526 2020 250,526 2021 147,558 Total minimum lease payments 648,610 Less deferred financial charges (95,593 ) Total capital lease obligations 553,017 Less: current portion of capital lease obligations 193,206 Total long term portion, net current portion 359,811

AMAK FAIR VALUE MEASUREMENT

AMAK FAIR VALUE MEASUREMENT	12 Months Ended
	Dec. 31, 2018
AMAK
Schedule of Equity Method Investments [Line Items]
Fair Value Measurement	Fair Value Measurement Fair value accounting guidance includes a hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 inputs) and the lowest priority to unobservable inputs (Level 3 inputs). Level 1 Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities; Level 2 Quoted prices in markets that are not active, quoted prices for similar assets or liabilities in active markets, inputs other than quoted prices that are observable for the asset or liability, or inputs that are derived principally from or corroborated by observable market data by correlation or other means; and Level 3 Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (supported by little or no market activity). We did not have any significant transfers in or out of Levels 1, 2, or 3 in 2018 or 2017 . The embedded derivatives in our provisional sales contracts are considered Level 2 measurements.

AMAK EMBEDDED DERIVATIVES

AMAK EMBEDDED DERIVATIVES	12 Months Ended
	Dec. 31, 2018
AMAK
Schedule of Equity Method Investments [Line Items]
Embedded Derivatives	Embedded Derivatives As described in Note 2 under Revenue Recognition, our concentrate sales contracts provide for provisional pricing based on the LME price at the time of shipment as specified in the contract. Sales contracts with a provisional sales price contain an embedded derivative (i.e., the price settlement mechanism that is settled after the time of delivery) that is required to be bifurcated from the host contract. The host contract is the sale of the metals contained in the concentrates at the then-current LME price as defined in the contract. Mark-to-market price fluctuations recorded through the settlement date are reflected in revenues for sales contracts. Our embedded derivatives at December 31, 2018 and 2017, were not significant to the financial statements.

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Principles of Consolidation	Principles of Consolidation – The consolidated financial statements include the balance sheets, statements of income, stockholders' equity, and cash flows of the Company, TOCCO, TC, SHR, GSPL and PEVM. Other entities which are not controlled but over which the Company has the ability to exercise significant influence such as AMAK, are accounted for using the equity method of accounting. All intercompany profits, transactions and balances have been eliminated.
Cash, Cash Equivalents and Short-Term Investments	Cash, Cash Equivalents and Short-Term Investments – Our principal banking and short-term investing activities are with local and national financial institutions. Short-term investments with an original maturity of three months or less are classified as cash equivalents.
Inventories	Inventories – Finished products and feedstock are recorded at the lower of cost, determined on the first-in, first-out method (FIFO), or market for SHR. For TC, inventory is recorded at the lower of cost or market as follows: (1) raw material cost is calculated using the weighted-average cost method and (2) product inventory cost is calculated using the specific cost method.
Trade Receivables and Allowance for Doubtful Accounts	Trade Receivables and Allowance for Doubtful Accounts – We evaluate the collectability of our trade receivables and adequacy of the allowance for doubtful accounts based upon historical experience and any specific customer financial difficulties of which we become aware. For the year ended December 31, 2018, we increased the balance by $152,000 due to concerns regarding collectability for a specific customer. For the year ended December 31, 2017, the allowance balance was not increased. In 2016, we increased the balance by $90,000 due to an increase in sales in countries where there is a greater risk of default and limited recourse should this occur. We track customer balances and past due amounts to determine if customers may be having financial difficulties. This, along with historical experience and a working knowledge of each customer, helps determine accounts that should be written off. No amounts were written off in 2018 or 2017.
Notes and Accounts Receivable	Notes Receivable – We periodically make changes in or expand our custom processing units at the request of the customer. The cost to make these changes is shared by the customer. Upon completion of a project a non-interest note receivable is recorded with an imputed interest rate. There were no notes receivable outstanding as of December 31, 2018. The interest rate used on outstanding notes during December 31, 2018 and 2017 was 4% . The unearned interest was reflected as a discount against the note balance. The Company evaluates the collectability of notes based upon a working knowledge of the customer. The notes are receivable from custom processing customers with whom we maintain a close relationship. Thus, all amounts due under the notes receivable are considered collectible, and no allowance was recorded at December 31, 2018 and 2017 , respectively.
Plant, Pipeline and Equipment	Plant, Pipeline and Equipment – Plant, pipeline and equipment are stated at cost. Depreciation is provided over the estimated service lives using the straight-line method. Gains and losses from disposition are included in operations in the period incurred. Maintenance and repairs are expensed as incurred. Major renewals and improvements are capitalized. Interest costs incurred to finance expenditures during construction phase are capitalized as part of the historical cost of constructing the assets. Construction commences with the development of the design and ends when the assets are ready for use. Capitalized interest costs are included in plant, pipeline and equipment and are depreciated over the service life of the related assets. Labor costs incurred to self-construct assets are capitalized as part of the historical cost the assets. Construction commences with the development of the design and ends when the assets are ready for use. Capitalized labor costs are included in plant, pipeline and equipment and are depreciated over the service life of the related assets. Platinum catalyst is included in plant, pipeline and equipment at cost. Amortization of the catalyst is based upon cost less estimated salvage value of the catalyst using the straight line method over the estimated useful life (see Note 8).
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets – Goodwill represents the future economic benefits arising from other assets acquired in the acquisition of TC that are not individually identified and separately recognized. Goodwill and indefinite-lived intangible assets are tested for impairment at least annually; however, these tests are performed more frequently when events or changes in circumstances indicate that the asset may be impaired. Impairment exists when carrying value exceeds fair value. Estimates of fair value are based on appraisals, market prices for comparable assets, or internal estimates of future net cash flows. Definite-lived intangible assets consist of customer relationships, licenses, permits and developed technology that were acquired as part of the Acquisition of TC. The majority of these assets are being amortized using discounted estimated future cash flows over the term of the related agreements. Intangible assets associated with customer relationships are being amortized using the discounted estimated future cash flows method based upon assumed rates of annual customer attrition. We continually evaluate the reasonableness of the useful lives of these assets. Once these assets are fully amortized, they will be removed from the consolidated balance sheets.
Business Combinations and Related Business Acquisition Costs	Business Combinations and Related Business Acquisition Costs – Assets and liabilities associated with business acquisitions are recorded at fair value using the acquisition method of accounting. We allocate the purchase price of acquisitions based upon the fair value of each component which may be derived from various observable and unobservable inputs and assumptions. We may use third-party valuation specialists to assist us in this allocation. Initial purchase price allocations are preliminary and subject to revision within the measurement period, not to exceed one year from the date of acquisition. The fair value of property, plant and equipment and intangible assets are based upon the discounted cash flow method that involves inputs that are not observable in the market (Level 3). Goodwill assigned represents the amount of consideration transferred in excess of the fair value assigned to identifiable assets acquired and liabilities assumed. Business acquisition costs are expensed as incurred and are reported as general and administrative expenses in the consolidated statements of income. We define these costs to include finder's fees, advisory, legal, accounting, valuation, and other professional consulting fees, as well as, travel associated with the evaluation and effort to acquire specific businesses.
Investment in AMAK	Investment in AMAK – We account for our investment in AMAK using the equity method of accounting under which we record in income our share of AMAK's income or loss for each period. The amount recorded is also adjusted to reflect the amortization of certain differences between the basis in our investment in AMAK and our share of the net assets of AMAK as reflected in AMAK's financial statements (see Note 10). Any proceeds received from or payments made to AMAK are recorded as decreases or increases in the balance of our investment. We assess our investment in AMAK for impairment when events are identified, or there are changes in circumstances that may have an adverse effect on the fair value of the investment. We consider recoverable ore reserves, changes in commodity prices, and the amount and timing of the cash flows to be generated by the production of those reserves, as well as, recent equity transactions within AMAK.
Other Assets	Other Assets – Other assets include a license used in specialty petrochemical operations, spare parts inventory and certain specialty petrochemical assets. Beginning January 1, 2017, due to the expansion of our plant assets at SHR and TC, we began inventorying spare parts for the repair and maintenance of our plant, pipeline and equipment. Spare parts are accounted for on the first-in, first-out method (FIFO).
Long-Lived Assets Impairment	Long-Lived Assets Impairment – Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable based on the undiscounted net cash flows to be generated from the asset's use. The amount of the impairment loss to be recorded is calculated by the excess of the asset's carrying value over its fair value. Fair value is generally determined using a discounted cash flow analysis although other factors including the state of the economy are considered.
Revenue Recognition and Shipping and Handling Costs	Revenue Recognition – The Company adopted Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("ASC") Topic 606 ("ASC 606"), Revenue from Contracts with Customers, and its amendments with a date of the initial application of January 1, 2018. As a result, the Company has changed its accounting policy for revenue recognition as detailed below. ASC 606 outlines a single comprehensive model for an entity to use in accounting for revenue arising from all contracts with customers, except where revenues are in scope of another accounting standard. ASC 606 superseded the revenue recognition requirements in ASC Topic 605, " Revenue Recognition", and most industry specific guidance. ASC Topic 606 sets forth a five-step model for determining when and how revenue is recognized. Under the model, an entity is required to recognize revenue to depict the transfer of goods or services to a customer at an amount reflecting the consideration it expects to receive in exchange for those goods and services. ASC 606 also requires certain additional revenue-related disclosures. The Company applied the modified retrospective approach under ASC 606 which allows for the cumulative effect of adopting the new guidance on the date of initial application. Use of the modified retrospective approach means the Company's comparative periods prior to initial application are not restated. The initial application was applied to all contracts at the date of the initial application. The Company has determined that the adjustments using the modified retrospective approach did not have a material impact on the date of the initial application along with the disclosure of the effect on prior periods. Accounting Policy Beginning on January 1, 2018, revenue is measured based on a consideration specified in a contract with a customer. The Company recognizes revenue when it satisfies a performance obligation by transferring control over a product or service to a customer. In evaluating when a customer has control of the asset we primarily consider whether the transfer of legal title and physical delivery has occurred, whether the customer has significant risks and rewards of ownership, and whether the customer has accepted delivery and a right to payment exists. Taxes assessed by a governmental authority that are both imposed on and concurrent with a specific revenue-producing transaction, that are collected by the Company from a customer, are excluded from revenue. Shipping and handling costs associated with outbound freight after control over a product has transferred to a customer are accounted for as a fulfillment cost and are included in cost of product sales and processing. The Company does not offer material rights of return or service-type warranties. For the year ended December 31, 2017 the Company recognized revenue according to FASB ASC Topic 605 ("ASC 605"), " Revenue Recognition" , when: (1) the customer accepted delivery of the product and title had been transferred or when the service was performed and the Company had no significant obligations remaining to be performed; (2) a final understanding as to specific nature and terms of the agreed upon transaction had occurred; (3) price was fixed and determinable; and (4) collection was assured. Product sales generally met these criteria, and revenue was recognized, when the product was delivered or title was transferred to the customer. Sales revenue was presented net of discounts, allowances, and sales taxes. Freight costs billed to customers were recorded as a component of revenue. Revenues received in advance of future sales of products or prior to the performance of services were presented as deferred revenues. Shipping and handling costs were classified as cost of product sales and processing and were expensed as incurred. Nature of goods and services The following is a description of principal activities – separated by reportable segments – from which the Company generates its revenue. For more detailed information about reportable segments, disaggregation of revenues, and contract balance disclosures, see Note 17. Specialty petrochemical segment The specialty petrochemical segment of the Company produces eight high purity hydrocarbons and other petroleum based products including isopentane, normal pentane, isohexane and hexane. These products are used in the production of polyethylene, packaging, polypropylene, expandable polystyrene, poly-iso/urethane foams, crude oil from the Canadian tar sands, and in the catalyst support industry. SHR's specialty petrochemical products are typically transported to customers by rail car, tank truck, iso-container and ship. Product Sales – The Company sells individual (distinct) products to its customers on a stand-alone basis (point-of-sale) without any further integration. There is no significant modification of any one or more products sold to fulfill another promised product or service within any of the Company's product sale transactions. The amount of consideration received for product sales is stated within the executed invoice with the customer. Payment is typically due and collected 30 to 60 days subsequent to point of sale. Processing Fees – The Company's services consist of processing customer supplied feedstocks into custom products including, if requested, services for forming, packaging, and arranging shipping. Pursuant to Tolling Agreements the customer retains title to the feedstocks and processed products. The performance obligation in each Tolling Agreement transaction is the processing of customer provided feedstocks into custom products and is satisfied over time. The amount of consideration received for product sales is stated within the executed invoice with the customer. Payment is typically due and collected within 30 days subsequent to point of sale. Specialty Wax segment The specialty wax segment of the Company manufactures and sells specialty polyethylene and poly alpha olefin waxes and also provides custom processing services for customers. Product Sales – The Company sells individual (distinct) products to its customers on a stand-alone basis (point-of-sale) without any further integration. There is no significant modification of any one or more products sold to fulfill another promised product or service within any of the Company's product sale transactions. The amount of consideration received for product sales is stated within the executed invoice with the customer. Payment is typically due and collected within 30 days subsequent to point of sale. Processing Fees – The Company's promised services consist of processing customer supplied feedstocks into custom products including, if requested, services for forming, packaging, and arranging shipping. Pursuant to Tolling Agreements and Purchase Order Arrangements, the customer typically retains title to the feedstocks and processed products. The performance obligation in each Tolling Agreement transaction and Purchase Order Arrangement is the processing of customer provided feedstocks into custom products and is satisfied over time. The amount of consideration received for product sales is stated within the executed invoice with the customer. Payment is typically due and collected within 30 days subsequent to point of sale. Shipping and Handling Costs – Shipping and handling costs are classified as cost of product sales and processing and are expensed as incurred.
Retirement Plan	Retirement Plan – We offer employees the benefit of participating in a 401(k) plan. We match 100% up to 6% of pay with vesting occurring over 2 years.
Environmental Liabilities	Environmental Liabilities – Remediation costs are accrued based on estimates of known environmental remediation exposure. Ongoing environmental compliance costs, including maintenance and monitoring costs, are expensed as incurred.
Other Liabilities	Other Liabilities – We periodically make changes in or expand our custom processing units at the request of the customer. The cost to make these changes is shared by the customer. Upon completion of a project a note receivable and a deferred liability are recorded to recover the project costs which are then capitalized. At times instead of a note receivable being established, the customer pays an upfront cost. The amortization of other liabilities is recorded as a reduction to depreciation expense over the life of the contract with the customer. As of December 31 of each year, depreciation expense was offset and reduced by approximately $0.8 million , $0.8 million , and $1.0 million , for 2018 , 2017 , and 2016 , respectively.
Net Income Per Share	Net Income Per Share – We compute basic income per common share based on the weighted-average number of common shares outstanding. Diluted income per common share is computed based on the weighted-average number of common shares outstanding plus the number of additional common shares that would have been outstanding if potential dilutive common shares, consisting of stock options, unvested restricted stock units, and shares which could be issued upon conversion of debt, had been issued (see Note 18).
Foreign Currency	Foreign Currency – The functional currency for the Company and each of the Company's subsidiaries is the US dollar (USD). Transaction gains or losses as a result of transactions denominated and settled in currencies other than the USD are reflected in the statements of income as foreign exchange transaction gains or losses. We do not employ any practices to minimize foreign currency risks. The functional and reporting currency of AMAK is the Saudi Riyal (SR). In June 1986 the SR was officially pegged to the USD at a fixed exchange rate of 1 USD to 3.75 SR; therefore, we translate SR into our reporting currency of the USD for income statement and balance sheet purposes using the fixed exchange rate. As of December 31, 2018 , 2017 and 2016 , foreign currency translation adjustments were not significant.
Management Estimates	Management Estimates – The preparation of consolidated financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. Significant estimates include allowance for doubtful accounts receivable and inventory obsolescence; assessment of impairment of our long-lived assets, goodwill, intangible assets and investments, litigation liabilities, post-retirement benefit obligations, guarantee obligations, environmental liabilities, income taxes and deferred tax valuation allowances. Actual results could differ from these estimates.
Share-Based Compensation	Share-Based Compensation – We recognize share-based compensation of stock options granted based upon the fair value of options on the grant date using the Black-Scholes pricing model (see Note 15). Share-based compensation expense recognized during the period is based on the fair value of the portion of share-based payments awards that is ultimately expected to vest. Share-based compensation expense recognized in the consolidated statements of operations for the years ended December 31, 2018 , 2017 , and 2016 includes compensation expense based on the estimated grant date fair value for awards that are ultimately expected to vest, and accordingly has been reduced for estimated forfeitures. Estimated forfeitures at the time of grant are revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates.
Guarantees	Guarantees – We may enter into agreements which contain features that meet the definition of a guarantee under FASB ASC 460 "Guarantees" (see Note 14). These arrangements create two types of obligations: a) We have a non-contingent and immediate obligation to stand ready to make payments if certain future triggering events occur. For certain guarantees, a liability is recognized for the stand ready obligation at the inception of the guarantee; and b) We have an obligation to make future payments if those certain future triggering events do occur. A liability for the payment under the guarantee is recognized when 1) it becomes probable that one or more future events will occur, triggering the requirement to make payments under the guarantee and 2) when the payment can be reasonably estimated.
Fair Value	Fair Value – The carrying value of cash and cash equivalents, trade receivables, taxes receivable, accounts payable, accrued liabilities, and other liabilities approximate fair value due to the immediate or short-term maturity of these financial instruments. The fair value of variable rate long term debt and notes payable reflect recent market transactions and approximate carrying value. We used other observable inputs that would qualify as Level 2 inputs to make our assessment of the approximate fair value of our cash and cash equivalents, trade receivables, taxes receivable, accounts payable, accrued liabilities, other liabilities, notes payable and variable rate long term debt. The fair value of the derivative instruments are described below. We measure fair value by ASC Topic 820 Fair Value. ASC Topic 820 defines fair value, establishes a framework for measuring fair value, and expands disclosures about fair value measurements. ASC Topic 820 applies to reported balances that are required or permitted to be measured at fair value under existing accounting pronouncements; accordingly, the standard amends numerous accounting pronouncements but does not require any new fair value measurements of reported balances. ASC Topic 820 emphasizes that fair value, among other things, is based on exit price versus entry price, should include assumptions about risk such as nonperformance risk in liability fair values, and is a market-based measurement, not an entity-specific measurement. When considering the assumptions that market participants would use in pricing the asset or liability, ASC Topic 820 establishes a fair value hierarchy that distinguishes between market participant assumptions based on market data obtained from sources independent of the reporting entity (observable inputs that are classified within Levels 1 and 2 of the hierarchy) and the reporting entity's own assumptions about market participant assumptions (unobservable inputs classified within Level 3 of the hierarchy). The fair value hierarchy prioritizes inputs used to measure fair value into three broad levels. In instances where the determination of the fair value measurement is based on inputs from different levels of the fair value hierarchy, the level in the fair value hierarchy within which the entire fair value measurement falls is based on the lowest level input that is significant to the fair value measurement in its entirety. Our assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment and considers factors specific to the asset or liability.
Derivatives	Derivatives – We record derivative instruments as either an asset or liability measured at fair value. Changes in the derivative instrument's fair value are recognized currently in earnings unless specific hedge accounting criteria are met. Special accounting for qualifying hedges allows a derivative instrument's gains and losses to offset related results on the hedged item in the income statement, to the extent effective, and requires that a company must formally document, designate and assess the effectiveness of transactions that receive hedge accounting.
Income Taxes	Income Taxes – Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. The Company maintains a valuation allowance for a deferred tax asset when it is deemed to be more likely than not that some or all of the deferred tax asset will not be realized. Our estimate of the potential outcome of any uncertain tax issues is subject to management's assessment of relevant risks, facts, and circumstances existing at that time. We use a more likely than not threshold for financial statement recognition and measurement of tax position taken or expected to be taken in a tax return. To the extent that our assessment of such tax position changes, the change in estimate is recorded in the period in which the determination is made. We report tax-related interest and penalties as a component of income tax expense. On December 22, 2017, Public Law No. 115-97 known as the Tax Cuts and Jobs Act (TCJA) was enacted. The TCJA included a number of changes to existing U.S. tax laws that impact the Company, most notably a reduction of the U.S. federal corporate income tax rate from a maximum of 35 percent to a flat 21 percent for tax years effective January 1, 2018. The TCJA also implemented a territorial tax system, provided for a one-time deemed repatriation tax on unrepatriated foreign earnings, eliminated the alternative minimum tax (AMT), made AMT credit carryforwards refundable, and permitted the acceleration of depreciation for certain assets placed into service after September 27, 2017. In addition the TJCA created prospective changes beginning in 2018, including repeal of the domestic manufacturing deduction, acceleration of tax revenue recognition, capitalization of research and development expenditures, additional limitations on executive compensation and limitations on the deductibility of interest. The Company has elected to recognize the income tax effects of the TCJA in its financial statements in accordance with Staff Accounting Bulletin 118 (SAB 118), which provides guidance for the application of ASC Topic 740 Income Taxes , in the reporting period in which the TCJA was signed into law. Under SAB 118 when a Company does not have the necessary information available, prepared, or analyzed (including computations) in reasonable detail to complete the accounting for certain income tax effects of the TCJA it will recognize provisional amounts if a reasonable estimate can be made. If a reasonable estimate cannot be made then no impact is recognized for the effect of the TCJA. SAB 118 permits an up to one year measurement period to finalize the measurement of the impact of the TCJA.
Reclassifications	Reclassifications – Certain reclassifications have been made to prior year balances to conform with the current year presentation.
Subsequent Events	Subsequent Events – The Company has evaluated subsequent events through March 15, 2019 , the date that the consolidated financial statements were approved by management.
New Accounting Pronouncements	New Accounting Pronouncements In May 2014 the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2014-9, Revenue from Contracts with Customers ("ASU 2014-9"). ASU 2014-9 supersedes the revenue recognition requirements of FASB Accounting Standards Codification ("ASC") Topic 605, Revenue Recognition and most industry-specific guidance throughout the Accounting Standards Codification, resulting in the creation of FASB ASC Topic 606, Revenue from Contracts with Customers . ASU 2014-9 requires entities to recognize revenue in a way that depicts the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled to in exchange for those goods or services. This ASU provides alternative methods of retrospective adoption and is effective for fiscal years, and interim periods within those years, beginning after December 15, 2017. The Company completed its assessment of the impact of the adoption of ASU 2014-9 across all revenue streams. This included reviewing current accounting policies and practices to identify potential differences that would result from applying the requirements under the new standard. We completed contract reviews and validated results of applying the new revenue guidance (Note 2). See Revenue Recognition policy note. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842). This update will increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. This update is effective for annual and interim reporting periods beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. In July 2018, the FASB issued ASU No. 2018-11, Targeted Improvements to ASC 842, Leases. ASU 2018-11 provided entities with an alternative modified transition method to elect not to recast the comparative periods presented when adopting ASC 842. The new standard provides a number of optional practical expedients in transition. The Company expects to elect: (1) the ‘package of practical expedients’, which permits it not to reassess under the new standard its prior conclusions about lease identification, lease classification, and initial direct costs and (2) the use-of-hindsight. In addition, the new standard provides practical expedients for an entity’s ongoing accounting that the Company anticipates making, such as the (1) the election for certain classes of underlying asset to not separate non-lease components from lease components and (2) the election for short-term lease recognition exemption for all leases that qualify. The Company will adopt ASU 842 as of January 1, 2019, using the alternative modified transition method. In preparation of adopting ASC 842, the Company is implementing additional internal controls to enable future preparation of financial information in accordance with ASC 842. The Company has also substantially completed its evaluation of the impact on the Company’s lease portfolio. The Company believes the largest impact will be on the consolidated balance sheets for the accounting of rail cars, equipment and office leases, which represents a majority of its operating leases it has entered into as a lessee. These leases will be recognized under the new standard as right of use assets (“ROU”) operating lease liabilities. The Company will also be required to provide expanded disclosures for its leasing arrangements. As of December 31, 2018, the Company had approximately $ 18.1 million of undiscounted future minimum operating lease commitments that are not recognized on its consolidated balance sheets as determined under the current standard. For a lessee, the results of operations are not expected to significantly change after adoption of the new standard. While substantially complete, the Company is still in the process of finalizing its evaluation of the effect of ASU 842 on the Company’s financial statements and disclosures, including the determination of the Company’s incremental borrowing rate for each of the operating leases to estimate the interest rate we would have to pay to borrow on a collateralized basis over a similar term for an amount equal to the lease payments. The Company will finalize its accounting assessment and quantitative impact of the adoption during the first quarter of fiscal year 2019. In January 2017 the FASB issued ASU No. 2017-4, Intangibles – Goodwill and Other (Topic 350) . The amendments in ASU 2017-4 simplify the measurement of goodwill by eliminating Step 2 from the goodwill impairment test. Instead, under these amendments, an entity should perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. An entity should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit's fair value; however, the loss should not exceed the total amount of goodwill allocated to that reporting unit. The amendments are effective for public business entities for the first interim and annual reporting periods beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017.The amendments also eliminate the requirements for any reporting unit with a zero or negative carrying amount to perform a qualitative assessment and, if it fails that qualitative test, to perform Step 2 of the goodwill impairment test. An entity still has the option to perform the qualitative assessment for a reporting unit to determine if the quantitative impairment test is necessary. The Company has goodwill from prior business combination and performs an annual impairment test or more frequently if changes or circumstances occur that would more-likely-than-not reduce the fair value of the reporting unit below its carrying value. During the year ended December 31, 2018 , the Company performed its impairment assessment and determined the fair value of the aggregated reporting units exceed the carrying value, such that the Company's goodwill was not considered impaired. Although the Company cannot anticipate future goodwill impairment assessments, based on the most recent assessment, it is unlikely that an impairment amount would need to be calculated and, therefore, the Company does not anticipate a material impact from these amendments to the Company's financial position and results of operations. The current accounting policies and processes are not anticipated to change, except for the elimination of the Step 2 analysis. In February 2018 the FASB issued ASU No. 2018-2, Income Statement — Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income . ASU 2018-2 was issued to address the income tax accounting treatment of the stranded tax effects within other comprehensive income due to the prohibition of backward tracing due to an income tax rate change that was initially recorded in other comprehensive income due to the enactment of the Tax Cuts and Jobs Act (TCJA) on December 22, 2017, which changed the Company's income tax rate from 35% to 21% . The amendments to the ASU changed US GAAP whereby an entity may elect to reclassify the stranded tax effect from accumulated other comprehensive income to retained earnings. The amendments of the ASU may be adopted in total or in part using a full retrospective or modified retrospective method. The amendments of the ASU are effective for periods beginning after December 15, 2018. The Company believes there will be no material impact to the consolidated financial statements as a result of this update. In June 2018, the FASB issued ASU No. 2018–07, Improvements to Nonemployee Share–Based Payment Accounting . ASU 2018–07 simplifies the accounting for share–based payments to nonemployees by aligning it with the accounting for share–based payments to employees, with certain exceptions. The amendments in this ASU are effective for public companies for fiscal years beginning after December 15, 2018, including interim periods within that fiscal year. The Company is assessing the effect of ASU 2018–02 on its consolidated financial statements.
AMAK
Schedule of Equity Method Investments [Line Items]
Cash, Cash Equivalents and Short-Term Investments	Cash and cash equivalents We consider all highly-liquid investments purchased with an original maturity of three months or less to be cash equivalents.
Inventories	Inventories The components of inventories include mill stockpiles, precious metal doré, chemicals, and mining supplies. Inventories are stated at the lower of weighted-average cost or market. Costs of mill stockpiles inventory include labor and benefits, supplies, energy, depreciation, depletion, amortization, and other necessary costs incurred with the extraction and processing of ore. Corporate general and administrative costs are not included in inventory costs. Because it is generally impracticable to determine the minerals contained in mill stockpiles by physical count, reasonable estimation methods are employed. The quantity of material delivered to the mill stockpiles is based on surveyed volumes of mined material and daily production records. Expected mineral recovery rates from the mill stockpiles are determined by various metallurgical testing methods.
Notes and Accounts Receivable	Accounts receivable We evaluate the collectability of our accounts receivable and the adequacy of the allowance for doubtful accounts based upon historical experience and any specific customer financial difficulties of which the Company becomes aware.
Plant, Pipeline and Equipment	Property and equipment Property and equipment is carried at cost less accumulated depreciation. Expenditures for replacements and improvements are capitalized. Costs related to periodic maintenance are expensed as incurred. Depletion of the mining assets is determined using the unit-of-production method based on total estimated proven and probable reserves. Depletion and amortization using the unit-of-production method is recorded upon extraction of the ore, at which time it is allocated to inventory cost and then included as a component of cost of goods sold. Other assets are depreciated on a straight-line basis over their estimated useful lives ranging from 3 to 20 years. Borrowing costs that are directly attributable to the acquisition, construction or production of assets are capitalized as part of the cost of those assets. Assets under construction are capitalized in the construction in progress account. Upon completion, the cost of the related asset is transferred to the appropriate category of property and equipment.
Long-Lived Assets Impairment	Asset impairment We review and evaluate our long-lived assets for impairment when events or changes in circumstances indicate that the carrying amounts may not be recoverable. Long-lived assets are evaluated for impairment under the two-step model. When events or circumstance suggest impairment of long-lived assets, estimated undiscounted future net cash flows are calculated using future estimated commodity prices, proven and probable reserves, and estimated net proceeds from the disposition of assets on retirement, less operating, sustaining capital, and reclamation costs. If it is determined that an impairment exists, an impairment loss is measured as the amount by which the asset carrying value exceeds its fair value. Fair value is generally determined using valuation techniques such as estimated future cash flows. Because the cash flows used to assess recoverability of our long-lived assets and measure fair value of our mining operations require us to make several estimates and assumptions that are subject to risk and uncertainty, changes in these estimates and assumptions could result in the impairment of our long-lived asset values.
Revenue Recognition and Shipping and Handling Costs	Revenue recognition We sell our products pursuant to sales contracts entered into with a customer who acts as an intermediary and resells our products to end users. Revenue is recognized when title and risk of loss pass to the customer and when collectability is reasonably assured. The passing of title and risk of loss to the customer is based on terms of the sales contract, generally upon shipment or delivery of product. Sales are recorded based on a provisional sales price or a final sales price calculated in accordance with the terms specified in the relevant sales contract. Under the long-established structure of sales agreements prevalent in the industry, the copper and zinc contained in concentrate is generally provisionally priced at the time of shipment. The provisional price received at the time of shipment is later adjusted to a final price based on quoted monthly average spot prices on the London Metal Exchange (LME) for a specified future month. We record revenues at the time of shipment (when title and risk of loss pass) based on then-current LME prices, and we account for any changes between the sales price recorded at the time of shipment and subsequent changes in the LME prices through the date of final pricing as gains or losses from a derivative embedded in the sales contract (a futures contract initiated at the date of shipment and settled upon the determination of the final price) which is bifurcated and separately accounted for at fair value. See Note 16. Revenues from concentrate sales are recorded net of treatment and refining charges. These allowances are a negotiated term of each contract. Treatment and refining charges represent payments or price adjustments to smelters and refiners and are either fixed, or in certain cases, vary with the price of metals (referred to as price participation).
Environmental Liabilities	Environmental costs Environmental costs are expensed or capitalized, depending upon their future economic benefits. Accruals for such expenditures are recorded when it is probable that obligations have been incurred and the costs can reasonably be estimated. Ongoing compliance costs are expensed as incurred.
Foreign Currency	Foreign currency Our functional currency is the Saudi Riyal (SR). In June 1986, the Saudi Riyal was officially pegged to the U.S. Dollar at a fixed exchange rate of 1 U.S. Dollar to 3.75 riyals. Foreign currency transactions are translated into Saudi Riyals at the rates of exchange prevailing at the time of the transactions. Monetary assets and liabilities denominated in foreign currencies at the balance sheet date are translated at the exchange rates prevailing at that date. Any gains and losses from settlement and translation of foreign currency transactions are included in the statement of operations.
Management Estimates	Management estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting periods. The most significant areas requiring the use of management estimates include mineral reserve estimation; useful asset lives for depreciation and amortization; zakat and income taxes; environmental obligations; reclamation and closure costs; estimates of recoverable materials in mill stockpiles; fair value of embedded derivatives; end-of-service indemnities; and asset impairment, including estimates used to derive future cash flows associated with those assets. Actual results could differ from these estimates.
Income Taxes	Zakat and income tax We are subject to the Regulations of the General Authority of Zakat and Tax (GAZT) in the Kingdom of Saudi Arabia. Under these regulations, Zakat is payable at 2.5% on the basis of the portion of our Zakat base attributable to our Saudi stockholders, and income tax is payable at 20% on the portion of our taxable income attributable to our non-Saudi stockholders. Zakat and income tax are provided on an accrual basis. Any difference in the estimate is recorded when the final assessment is approved, at which time the provision is cleared. We account for deferred income taxes on non-Saudi owners utilizing an asset and liability method, whereby deferred tax assets and liabilities are recognized based on the tax effects of temporary differences between the financial statements and the income tax basis of assets and liabilities, as measured by the effective tax rate. When appropriate, we evaluate the need for a valuation allowance based on a more likely than not threshold to reduce deferred tax assets to estimated recoverable amounts. We account for uncertain income tax positions using a threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. We report tax-related interest and penalties as a component of Zakat and income tax expense. We recognized no material adjustment for unrecognized income tax liabilities. Zakat and income tax returns for the years from 2010 to 2017 are currently under review with GAZT.
Reclassifications	Reclassifications Certain reclassifications have been made to the prior periods to conform with current year presentation.
Subsequent Events	Subsequent events We have evaluated events and transactions subsequent to the date of the financial statements for matters requiring recognition or disclosure in the financial statements. The accompanying financial statements consider events through March 6, 2019, the date on which the financial statements were available to be issued.
New Accounting Pronouncements	Recent accounting pronouncements In May 2014 the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2014-09, Revenue from Contracts with Customers ("ASU 2014-09"). ASU 2014-09 supersedes the revenue recognition requirements of FASB Accounting Standards Codification ("ASC") Topic 605, Revenue Recognition and most industry-specific guidance throughout the Accounting Standards Codification, resulting in the creation of FASB ASC Topic 606, Revenue from Contracts with Customers. ASU 2014-09 requires entities to recognize revenue in a way that depicts the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled to in exchange for those goods or services. For nonpublic companies this ASU provides alternative methods of retrospective adoption and is effective for fiscal years and interim periods beginning after December 15, 2018. Early adoption is permitted. The Company is evaluating the impact of these amendments, although it does not expect the amendments to have a significant impact to the Company’s financial position or results of operation. In February 2016 the FASB issued ASU No. 2016-02, Leases (Topic 842), to increase transparency and comparability among organizations by recognizing all lease transactions (with terms in excess of 12 months) on the balance sheet as a lease liability and a right-of-use asset (as defined). The ASU is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, with earlier application permitted. Upon adoption, the lessee will apply the new standard retrospectively to all periods presented or retrospectively using a cumulative effect adjustment in the year of adoption. The Company has several lease agreements for which the amendments will require the Company to recognize a lease liability to make lease payments and a right-of-use asset which will represent its right to use the underlying asset for the lease term. As permitted by the amendments, the Company is anticipating electing an accounting policy to not recognize lease assets and lease liabilities for leases with a term of twelve months or less. The Company is currently reviewing the amendments to ensure it is fully compliant by the adoption date and does not expect to early adopt. In addition, the Company will change its current accounting policies to comply with the amendments with such changes as mentioned above.
Basis of Accounting	The accompanying financial statements have been prepared using U.S. generally accepted accounting principles.
Development costs	Development costs Mineral exploration costs, as well as drilling and other costs incurred for the purpose of converting mineral resources to proven and probable reserves or identifying new mineral resources are charged to expense as incurred. Development costs are capitalized beginning after proven and probable reserves have been established. Development costs include costs incurred in mine pre-production activities undertaken to gain access to proven and probable reserves, including shafts, drifts, ramps, permanent excavations, infrastructure and removal of overburden. These costs are deferred net of the proceeds from the sale of any production during the development period and then amortized using an estimated unit-of-production method. If a mine is no longer considered economical, the accumulated costs are charged to the statement of operations in the year in which the determination is made.
End-of-service indemnities	End-of-service indemnities Employee end-of-service benefits are accrued for the benefit of employees under the terms and conditions of Saudi Labor Law and Regulations and their employment contracts. End-of-service indemnities are provided for and accrued in the financial statements based on the respective employees' salaries and length of service.
Pre-export Advances	Pre-export Advances At times we receive advances on a pre-export basis against a portion of our inventory on hand prior to shipment. These advances bear interest at 2.5% and are repaid from the proceeds from final concentrate sales.
Leasing arrangements	Leasing arrangements We periodically lease operating equipment, facilities, and office buildings. Rentals payable under operating leases are charged to the statements of operations on a straight-line basis over the term of the relevant lease. For any capital leases, the present value of future minimum lease payments at the inception of the lease is reflected as an asset and a liability in the balance sheet. Amounts due within one year are classified as short-term liabilities and the remaining balance as long-term liabilities. Finance charges are charged to the statement of operations.
Asset retirement obligations and costs	Asset retirement obligations and costs We record the fair value of our estimated asset retirement obligations (AROs) associated with tangible long-lived assets in the period in which the obligation is incurred. AROs associated with long-lived assets are those for which there is a legal obligation to settle under various laws, statues, or regulations. These obligations, which are initially estimated based on discounted cash flow estimates, are accreted to full value over time through charges to cost of revenues. In addition, asset retirement costs (ARCs) are capitalized as part of the related asset’s carrying value and are depreciated (primarily on a unit-of-production basis) over the asset’s respective useful life. Our AROs consist primarily of costs associated with mine reclamation and closure activities and are included in deferred mine closure costs on the accompanying balance sheets. At least annually, we review our ARO estimates for changes in the projected timing and changes in cost estimates and additional AROs incurred during the period.
Fair Value Measurement	Fair value accounting guidance includes a hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 inputs) and the lowest priority to unobservable inputs (Level 3 inputs). Level 1 Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities; Level 2 Quoted prices in markets that are not active, quoted prices for similar assets or liabilities in active markets, inputs other than quoted prices that are observable for the asset or liability, or inputs that are derived principally from or corroborated by observable market data by correlation or other means; and Level 3 Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (supported by little or no market activity). We did not have any significant transfers in or out of Levels 1, 2, or 3 in 2018 or 2017 . The embedded derivatives in our provisional sales contracts are considered Level 2 measurements.

ACQUISITION OF B PLANT (Tables)

ACQUISITION OF B PLANT (Tables)	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Schedule of Bargain of Purchase Gain	We recorded an $11.5 million bargain purchase gain on the transaction as calculated in the table below (in thousands). Cash paid $ 2,011 Estimated earnout liability 733 Purchase Price $ 2,744 Fixed assets at FMV Land 980 Site improvements 30 Buildings 1,350 Production equipment 11,933 14,293 Bargain purchase gain $ 11,549

TRADE RECEIVABLES (Tables)

TRADE RECEIVABLES (Tables)	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Schedule of Trade Receivables, net	Trade receivables, net, at December 31, consisted of the following: 2018 2017 (thousands of dollars) Trade receivables $ 27,564 $ 26,079 Less allowance for doubtful accounts (452 ) (300 ) Trade receivables, net $ 27,112 $ 25,779

PREPAID EXPENSES AND OTHER AS_2

PREPAID EXPENSES AND OTHER ASSETS (Tables)	12 Months Ended
	Dec. 31, 2018
Prepaid Expense and Other Assets, Current [Abstract]
Schedule of Prepaid Expenses and Other Assets	Prepaid expenses and other assets at December 31 are summarized as follows: 2018 2017 (thousands of dollars) Prepaid license $ 2,419 $ 1,919 Spare parts 1,597 954 Other prepaid expenses and assets 648 772 Total $ 4,664 $ 3,645

INVENTORIES (Tables)

INVENTORIES (Tables)	12 Months Ended
	Dec. 31, 2018
Inventory Disclosure [Abstract]
Inventories	Inventories include the following at December 31: 2018 2017 (thousands of dollars) Raw material $ 4,742 $ 3,703 Work in process 173 27 Finished products 11,624 14,720 Total inventory $ 16,539 $ 18,450

PLANT, PIPELINE AND EQUIPMENT (

PLANT, PIPELINE AND EQUIPMENT (Tables)	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Plant, Pipeline and Equipment	Plant, pipeline and equipment include the following at December 31: 2018 2017 (thousands of dollars) Platinum catalyst $ 1,612 $ 1,612 Catalyst 3,131 779 Land 5,428 5,428 Plant, pipeline and equipment 253,905 186,946 Construction in progress 4,343 50,996 Total plant, pipeline and equipment 268,419 245,761 Less accumulated depreciation (73,762 ) (63,240 ) Net plant, pipeline and equipment $ 194,657 $ 182,521

GOODWILL AND INTANGIBLE ASSET_2

GOODWILL AND INTANGIBLE ASSETS, NET (Tables)	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of Finite-Lived Intangible Assets by Major Class	The following table summarizes the gross carrying amounts and accumulated amortization of intangible assets by major class (in thousands): December 31, 2018 Intangible assets subject to amortization (Definite-lived) Gross Accumulated Amortization Net Customer relationships $ 16,852 $ (4,775 ) $ 12,077 Non-compete agreements 94 (80 ) 14 Licenses and permits 1,471 (495 ) 976 Developed technology 6,131 (2,606 ) 3,525 24,548 (7,956 ) 16,592 Intangible assets not subject to amortization (Indefinite-lived) Emissions Allowance 197 — 197 Trade name 2,158 — 2,158 Total $ 26,903 $ (7,956 ) $ 18,947 December 31, 2017 Intangible assets subject to amortization (Definite-lived) Gross Accumulated Amortization Net Customer relationships $ 16,852 $ (3,651 ) $ 13,201 Non-compete agreements 94 (61 ) 33 Licenses and permits 1,471 (390 ) 1,081 Developed technology 6,131 (1,993 ) 4,138 24,548 (6,095 ) 18,453 Intangible assets not subject to amortization (Indefinite-lived) Emissions Allowance 197 — 197 Trade name 2,158 — 2,158 Total $ 26,903 $ (6,095 ) $ 20,808
Summary of Indefinite-Lived Intangible Assets by Major Class	The following table summarizes the gross carrying amounts and accumulated amortization of intangible assets by major class (in thousands): December 31, 2018 Intangible assets subject to amortization (Definite-lived) Gross Accumulated Amortization Net Customer relationships $ 16,852 $ (4,775 ) $ 12,077 Non-compete agreements 94 (80 ) 14 Licenses and permits 1,471 (495 ) 976 Developed technology 6,131 (2,606 ) 3,525 24,548 (7,956 ) 16,592 Intangible assets not subject to amortization (Indefinite-lived) Emissions Allowance 197 — 197 Trade name 2,158 — 2,158 Total $ 26,903 $ (7,956 ) $ 18,947 December 31, 2017 Intangible assets subject to amortization (Definite-lived) Gross Accumulated Amortization Net Customer relationships $ 16,852 $ (3,651 ) $ 13,201 Non-compete agreements 94 (61 ) 33 Licenses and permits 1,471 (390 ) 1,081 Developed technology 6,131 (1,993 ) 4,138 24,548 (6,095 ) 18,453 Intangible assets not subject to amortization (Indefinite-lived) Emissions Allowance 197 — 197 Trade name 2,158 — 2,158 Total $ 26,903 $ (6,095 ) $ 20,808
Schedule of Expected Future Amortization Expenses	Based on identified intangible assets that are subject to amortization as of December 31, 2018 , we expect future amortization expenses for each period to be as follows (in thousands): Total 2019 2020 2021 2022 2023 Thereafter Customer relationships $ 12,077 $ 1,123 $ 1,123 $ 1,123 $ 1,123 $ 1,123 $ 6,462 Non-compete agreements 14 14 — — — — — Licenses and permits 976 106 106 101 86 86 491 Developed technology 3,525 613 613 613 613 613 460 Total future amortization expense $ 16,592 $ 1,856 $ 1,842 $ 1,837 $ 1,822 $ 1,822 $ 7,413

INVESTMENT IN AL MASANE AL KO_2

INVESTMENT IN AL MASANE AL KOBRA MINING COMPANY ("AMAK") (Tables)	12 Months Ended
	Dec. 31, 2018
Equity Method Investments and Joint Ventures [Abstract]
Summarized Results of Operation and Financial Position for AMAK	The summarized results of operation and financial position for AMAK are as follows: Results of Operations Years Ended December 31, 2018 2017 2016 (Thousands of Dollars) Sales $ 70,234 $ 36,435 $ 9,921 Cost of sales (68,084 ) (43,304 ) (27,132 ) Gross loss 2,150 (6,869 ) (17,211 ) General, administrative and other expenses 8,879 9,903 9,690 Loss from operations $ (6,729 ) $ (16,772 ) $ (26,901 ) Gain on settlement with former operator — — 17,425 Net loss $ (6,729 ) $ (16,772 ) $ (9,476 ) Depreciation and amortization 33,469 22,419 11,672 Net income before depreciation and amortization $ 26,740 $ 5,648 $ 2,196 Financial Position December 31, 2018 2017 (Thousands of Dollars) Current assets $ 44,093 $ 23,333 Noncurrent assets 212,291 237,875 Total assets $ 256,384 $ 261,208 Current liabilities $ 17,160 $ 24,439 Long term liabilities 77,366 68,837 Shareholders' equity 161,858 167,932 Total liabilities and equity $ 256,384 $ 261,208
Equity in Income or Loss of AMAK Reflected on Consolidated Statements	The equity in the income or loss of AMAK reflected on the consolidated statements of income for the years ended December 31, 2018 , 2017 , and 2016 , is comprised of the following: 2018 2017 2016 AMAK Net Loss $ (6,729 ) $ (16,772 ) $ (9,476 ) Zakat tax applicable to Saudi Arabian shareholders only — — 320 AMAK Net Loss before Saudi Arabian shareholders' portion of Zakat $ (6,729 ) $ (16,772 ) $ (9,156 ) Company's share of loss reported by AMAK (33.41% beginning July 10, 2016 and 35.25% prior to July 10, 2016) $ (2,248 ) $ (5,608 ) $ (2,826 ) Amortization of difference between Company's investment in AMAK and Company's share of net assets of AMAK 1,347 1,347 1,347 Equity in loss of AMAK $ (901 ) $ (4,261 ) $ (1,479 )
Shareholders and Percentages Owned	The following table shows AMAK shareholders and percentages owned at December 31, 2018: Name Percentage Owned Various Saudi shareholders 46.73 % Trecora Resources 33.41 % Armico 19.86 % Total 100.00 %

LONG-TERM DEBT AND LONG-TERM _2

LONG-TERM DEBT AND LONG-TERM OBLIGATIONS (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Long-term Debt and Long-term Obligations	Long-term debt and long-term obligations at December 31 are summarized as follows: 2018 2017 (thousands of dollars) Revolving facility $ 18,000 $ 35,000 Term loan facility 85,312 47,250 Acquisition loan — 17,333 Loan fees (830 ) (501 ) Total long-term debt 102,482 99,082 Less current portion including loan fees 4,194 8,061 Total long-term debt, less current portion including loan fees $ 98,288 $ 91,021
Schedule of Principal Payments of Long-term Debt	Principal payments of long-term debt for the next five years and thereafter ending December 31 are as follows: Year Ending December 31, Long-Term Debt (thousands of dollars) 2019 4,375 2020 4,375 2021 4,375 2022 4,375 2023 85,812 Total 103,312

ACCRUED LIABILITIES (Tables)

ACCRUED LIABILITIES (Tables)	12 Months Ended
	Dec. 31, 2018
Accrued Liabilities [Abstract]
Accrued Liabilities	Accrued liabilities at December 31 are summarized as follows: 2018 2017 (thousands of dollars) Accrued state taxes $ 210 $ 272 Accrued payroll 936 1,407 Accrued interest 31 30 Accrued officer compensation — 500 Accrued restructuring & severance expenses (Note 21) 1,221 — Accrued foreign taxes 802 — Other liabilities 2,239 1,752 Total $ 5,439 $ 3,961

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Property and Equipment Lease Payments	Future minimum property and equipment lease payments under the non-cancelable operating leases at December 31, 2018 , are as follows: Year Ending December 31, (thousands of dollars) 2019 $ 3,670 2020 3,583 2021 3,418 2022 3,107 2023 2,288 Thereafter 2,065 Total $ 18,131

SHARE-BASED COMPENSATION (Table

SHARE-BASED COMPENSATION (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Status of Stock Option Awards and Warrants	A summary of the status of the Company’s stock option and warrant awards is as follows: Stock Options and Warrants Weighted Average Exercise Price Per Share Weighted Average Remaining Contractual Life Intrinsic Value (in thousands) Outstanding at January 1, 2018 1,323,587 $ 7.82 Granted — — Expired — — Exercised (377,757 ) 5.21 Forfeited (200,000 ) 3.40 Outstanding at December 31, 2018 745,830 $ 10.33 4.6 $ — Expected to vest — $ — 0.0 $ — Exercisable at December 31, 2018 745,830 $ 10.33 4.6 $ —
Schedule of Nonvested Share Activity	A summary of the status of the Company's non-vested options that are expected to vest is presented below: Shares Weighted Average Grant-Date Fair Value Per Share Non-vested at January 1, 2018 325,000 $ 6.81 Granted — — Forfeited (200,000 ) 3.40 Vested (125,000 ) 12.26 Non-vested at December 31, 2018 — $ —
Restricted Stock Units Activity	A summary of the status of the Company's restricted stock units activity is as follows: Shares of Restricted Stock Units Weighted Average Grant Date Price per Share Outstanding at January 1, 2018 387,702 $ 11.39 Granted 226,908 11.45 Forfeited (103,637 ) 11.39 Vested (105,298 ) 11.99 Outstanding at December 31, 2018 405,675 $ 11.27 Expected to vest 405,675

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Provision for Income Taxes	The provision for income taxes consisted of the following: Year ended December 31, 2018 2017 2016 (thousands of dollars) Current federal provision (benefit) $ (74 ) $ (1,202 ) $ 1,691 Current state provision 31 282 18 Deferred federal provision (benefit) (974 ) (6,320 ) 8,645 Deferred state provision 210 81 150 Income tax expense (benefit) $ (807 ) $ (7,159 ) $ 10,504
Schedule of Effective Income Tax Rate Reconciliation	The difference between the effective tax rate in income tax expense and the Federal statutory rate of 21% for the year ended December 31, 2018 , and 35% for the years ended December 31 2017 and 2016 , is as follows: 2018 2017 2016 (thousands of dollars) Income taxes at U.S. statutory rate $ (822 ) $ 3,885 $ 10,476 State taxes, net of federal benefit 234 235 285 Net operating loss carryback — (961 ) — Research and development credits (263 ) — — Permanent and other items 44 (11 ) (257 ) Deferred tax impact of US tax reform — (10,307 ) — Total tax expense (benefit) $ (807 ) $ (7,159 ) $ 10,504
Tax Effects of Temporary Differences	Tax effects of temporary differences that give rise to significant portions of federal and state deferred tax assets and deferred tax liabilities were as follows: December 31, 2018 2017 (thousands of dollars) Deferred tax liabilities: Plant, pipeline and equipment $ (25,169 ) $ (17,014 ) Intangible assets (1,075 ) (778 ) Other assets (40 ) (4 ) Investment in AMAK (671 ) (1,023 ) Total deferred tax liabilities $ (26,955 ) $ (18,819 ) Deferred tax assets: Accounts receivable 238 198 Inventory 133 156 Mineral interests 226 226 Foreign tax credit 802 — Net operating loss carryforward 9,073 — Post-retirement benefits 79 252 Stock-based compensation 954 971 Gross deferred tax assets 11,505 1,803 Valuation allowance (226 ) (226 ) Total net deferred tax assets $ 11,279 $ 1,577 Net deferred tax liabilities $ (15,676 ) $ (17,242 )

SEGMENT INFORMATION (Tables)

SEGMENT INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Segment Information	We also separately identify our corporate overhead which includes financing and administrative activities such as legal, accounting, consulting, investor relations, officer and director compensation, corporate insurance, and other administrative costs. Year Ended December 31, 2018 Specialty Petrochemical Specialty Wax Corporate Consolidated (in thousands) Net revenues $ 249,679 $ 38,253 $ — $ 287,932 Operating profit (loss) before depreciation and amortization 23,021 1,949 (8,275 ) 16,695 Operating profit (loss) 14,089 (3,427 ) (8,327 ) 2,335 Profit (loss) before taxes 10,705 (4,660 ) (9,184 ) (3,139 ) Depreciation and amortization 8,932 5,376 50 14,358 Capital expenditures 22,431 2,854 — 25,285 Year Ended December 31, 2018 Specialty Petrochemical Specialty Wax Corporate Eliminations Consolidated (in thousands) Goodwill and intangible assets, net $ — $ 40,745 $ — $ — $ 40,745 Total assets 284,367 115,366 91,474 (161,239 ) 329,968 Year Ended December 31, 2017 Specialty Petrochemical Specialty Wax Corporate Consolidated (in thousands) Net revenues $ 210,381 $ 34,762 $ — $ 245,143 Operating profit (loss) before depreciation and amortization 36,511 (35 ) (7,413 ) 29,063 Operating profit (loss) 30,201 (4,624 ) (7,475 ) 18,102 Profit (loss) before taxes 27,852 (5,238 ) (11,764 ) 10,850 Depreciation and amortization 6,310 4,589 62 10,961 Capital expenditures 38 14,015 — 14,053 Year Ended December 31, 2017 Specialty Petrochemical Specialty Wax Corporate Eliminations Consolidated (in thousands) Goodwill and intangible assets, net $ — $ 42,606 $ — $ — $ 42,606 Total assets 265,213 117,579 97,880 (153,346 ) 327,326

NET INCOME (LOSS) PER COMMON _2

NET INCOME (LOSS) PER COMMON SHARE (Tables)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Net Income (Loss) Per Common Share	Year ended December 31, 2018 2017 2016 (thousands of dollars) Net income (loss) $ (2,332 ) $ 18,009 $ 19,428 Basic earnings (loss) per common share: Weighted average shares outstanding 24,438 24,294 24,284 Per share amount (dollars) $ (0.10 ) $ 0.74 $ 0.80 Diluted earnings (loss) per common share: Weighted average shares outstanding 24,438 25,129 24,982 Per share amount (dollars) $ (0.10 ) $ 0.72 $ 0.78 Weighted average shares-denominator basic computation 24,438 24,294 24,284 Unvested restricted stock unit grant — 367 310 Effect of dilutive stock options — 468 388 Weighted average shares, as adjusted denominator diluted computation 24,438 25,129 24,982

QUARTERLY RESULTS OF OPERATIO_2

QUARTERLY RESULTS OF OPERATIONS (UNAUDITED) (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information	The quarterly results of operations shown below are derived from unaudited financial statements for the eight quarters ended December 31, 2018 (in thousands, except per share data, rounding may apply): Year Ended December 31, 2018 First Quarter Second Quarter Third Quarter Fourth Quarter Total Revenues $ 71,741 $ 68,106 $ 73,416 $ 74,669 $ 287,932 Gross profit 10,140 8,142 6,842 2,694 27,818 Net income (loss) 2,352 2,215 (1,609 ) (5,290 ) (2,332 ) Basic EPS (1) $ 0.10 $ 0.09 $ (0.07 ) $ (0.22 ) $ (0.10 ) Diluted EPS (1) $ 0.09 $ 0.09 $ (0.07 ) $ (0.22 ) $ (0.10 ) Year Ended December 31, 2017 First Quarter Second Quarter Third Quarter Fourth Quarter (2) Total Revenues $ 55,542 $ 62,115 $ 61,508 $ 65,978 $ 245,143 Gross profit 10,618 11,107 9,870 9,966 41,561 Net income 1,487 832 1,718 13,972 18,009 Basic EPS (1) $ 0.06 $ 0.03 $ 0.07 $ 0.58 $ 0.74 Diluted EPS (1) $ 0.06 $ 0.03 $ 0.07 $ 0.56 $ 0.72 (1) Basic and diluted earnings per share are computed independently for each of the quarters presented based on the weighted average number of common shares outstanding during that period. Therefore, the sum of quarterly basic and diluted per share information may not equal annual basic and diluted earnings per share. (2) As discussed in Note 16 the TCJA changed the federal corporate income tax rates from 35% to 21% resulting in a benefit from deferred taxes of approximately $10.3 million .

AMAK FINANCIAL STATEMENTS (Tabl

AMAK FINANCIAL STATEMENTS (Tables) - AMAK	12 Months Ended
	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Balance Sheets	Balance Sheets December 31, 2018 2017 (Expressed in Saudi Riyals) ASSETS Current assets: Cash and cash equivalents 31,510,496 32,325,537 Accounts receivable 16,235,035 8,213,816 Inventories 45,871,120 27,226,932 Advances to shareholders (Note 1) 52,562,028 — Advances to contractors and other 19,168,765 19,731,780 Total current assets 165,347,444 87,498,065 Non-current assets: Property and equipment, net 634,856,075 693,801,671 Development costs, net 155,281,525 191,528,180 Deferred mine closure costs 5,955,999 6,700,499 Total non-current assets 796,093,599 892,030,350 961,441,043 979,528,415 LIABILITIES AND SHAREHOLDERS' EQUITY Current liabilities: Accounts payable and accrued liabilities 28,756,945 22,672,618 Zakat and income tax liability 5,400,000 3,516,673 Due to shareholders — 453,816 Capital lease obligation, current portion 193,206 — Long-term debt, current portion 30,000,000 65,000,000 Total current liabilities 64,350,151 91,643,107 Non-current liabilities Provision for mine closure costs 16,063,136 15,519,938 Capital lease obligation, net of current portion 359,811 — Long-term debt, net of current portion and deferred finance costs 266,258,712 229,082,810 End-of-service indemnities 3,649,889 2,518,529 Deferred income taxes 3,792,785 11,017,714 Total non-current liabilities 290,124,333 258,138,991 Balance Sheets - (Continued) December 31, 2018 2017 (Expressed in Saudi Riyals) Commitments and contingencies (Note 14) Shareholders' equity Share capital 820,000 780,000 Share premium — 37,546 Accumulated deficit (213,033 ) (187,800 ) Total shareholders' equity 606,967 629,746 961,441 979,528
Statements of Operations	Statements of Operations December 31, 2018 2017 2016 (Expressed in Saudi Riyals) Revenues 263,377,273 136,629,881 37,202,504 Costs of revenues 255,313,296 162,388,373 101,743,839 Operating income (loss) 8,063,977 (25,758,492 ) (64,541,335 ) General and administrative expenses 29,475,998 28,299,733 26,957,555 Loss from operations (21,412,021 ) (54,058,225 ) (91,498,890 ) Other income (expense) Gain on forgiveness of liabilities and spare parts (Note 8) — — 65,345,250 Finance charges (5,969,821 ) (6,103,680 ) (6,043,410 ) Other income 323,575 893,524 260,953 (5,646,246 ) (5,210,156 ) 59,562,793 Loss before Zakat and income tax (27,058,267 ) (59,268,381 ) (31,936,097 ) Zakat and income tax benefit (expense) 1,824,929 (3,627,193 ) (3,596,244 ) Net loss (25,233,338 ) (62,895,574 ) (35,532,341 )
Statements of Changes in Shareholders' Equity	Statements of Changes in Shareholders' Equity (Expressed in Saudi Riyals) Retained Earnings Share Share (Accumulated Capital Premium Deficit) Total Balance at December 31, 2015 740,000,000 — (89,372,188 ) 650,627,812 Issuance of share capital and premium 40,000,000 37,546,420 — 77,546,420 Net loss — — (35,532,341 ) (35,532,341 ) Balance at December 31, 2016 780,000,000 37,546,420 (124,904,529 ) 692,641,891 Net loss — — (62,895,574 ) (62,895,574 ) Balance at December 31, 2017 780,000,000 37,546,420 (187,800,103 ) 629,746,317 Issuance of share premium — 2,453,580 — 2,453,580 Conversion of share premium to share capital 40,000,000 (40,000,000 ) — — Net loss — — (25,233,338 ) (25,233,338 ) Balance at December 31, 2018 820,000,000 — (213,033,441 ) 606,966,559
Statements of Cash Flows	Statements of Cash Flows December 31, 2018 2017 2016 (Expressed in Saudi Riyals) Cash flows from operating activities: Net loss (25,233,338 ) (62,895,574 ) (35,532,341 ) Adjustments to reconcile net loss to net cash provided by (used in) operating activities: Depreciation and amortization 125,507,864 83,547,586 43,768,238 Accretion of deferred mine closure costs 543,198 524,829 507,081 Amortization of deferred finance costs 2,175,902 1,610,733 2,147,644 Gain on forgiveness of liabilities — — (65,345,250 ) Deferred income taxes (7,224,929 ) 417,966 1,718,258 Changes in operating assets and liabilities: Accounts receivable (8,021,219 ) (8,213,816 ) 28,351,618 Inventories (18,644,188 ) (11,351,752 ) 15,754,952 Advances to contractors and other 563,016 (3,944,995 ) (6,186,357 ) Accounts payable and accrued liabilities 6,084,327 9,638,009 3,511,632 Zakat and income tax liability 1,883,327 1,583,048 679,206 Pre-export advance payment — — (9,150,880 ) End-of-service indemnities 1,131,360 1,037,893 (264,797 ) Net cash provided by (used in) operating activities 78,765,320 11,953,927 (20,040,996 ) Cash flows from investing activities: Additions to property and equipment (28,945,309 ) (31,550,443 ) (29,246,001 ) Statements of Cash Flows - (Continued) December 31, 2018 2017 2016 (Expressed in Saudi Riyals) Cash flows from financing activities: Issuance of share capital and premium 2,453,580 — 75,092,840 Payments on capital lease obligations (72,788 ) — — Payments on long-term debt — (5,000,000 ) — Net advances from (to) shareholders (53,015,844 ) 403,147 299,231 Net cash provided by (used in) financing activities (50,635,052 ) (4,596,853 ) 75,392,071 Increase (decrease) in cash and cash equivalents (815,041 ) (24,193,369 ) 26,105,074 Cash and cash equivalents, beginning of year 32,325,537 56,518,906 30,413,832 Cash and cash equivalents, end of year 31,510,496 32,325,537 56,518,906 Supplemental cash flow information Cash paid for interest 3,927,778 3,686,000 3,895,766 Cash paid for Zakat and income tax 3,212,813 1,626,179 1,198,780 Supplemental disclosure of non-cash items Assets acquired through capital lease obligations 625,805 — —

AMAK ORGANIZATION AND BUSINESS

AMAK ORGANIZATION AND BUSINESS (Tables)	12 Months Ended
	Dec. 31, 2018
AMAK
Schedule of Equity Method Investments [Line Items]
Schedule of Ownership in Joint Stock Company	Except for Trecora and ARMICO, all other shareholders are Saudi nationals or companies wholly owned by Saudi nationals. Our ownership is as follows: Shares Ownership Percentage Saudi shareholders 38,349,184 46.8 Trecora (US Company) 27,402,876 33.4 ARMICO (Pan Arab Organization) 16,247,940 19.8 82,000,000 100.00

AMAK INVENTORIES (Tables)

AMAK INVENTORIES (Tables)	12 Months Ended
	Dec. 31, 2018
Inventory [Line Items]
Inventories	Inventories include the following at December 31: 2018 2017 (thousands of dollars) Raw material $ 4,742 $ 3,703 Work in process 173 27 Finished products 11,624 14,720 Total inventory $ 16,539 $ 18,450
AMAK
Inventory [Line Items]
Inventories	Inventories consisted of the following at: December 31, 2018 2017 Ore concentrates 17,020,657 12,118,132 Stockpile ore 19,134,297 9,417,626 Precious metal dore 2,159,192 — Explosives 1,134,728 485,668 Chemicals and other 6,422,246 5,205,506 45,871,120 27,226,932

AMAK ADVANCES TO CONTRACTORS _2

AMAK ADVANCES TO CONTRACTORS AND OTHER (Tables)	12 Months Ended
	Dec. 31, 2018
AMAK
Schedule of Equity Method Investments [Line Items]
Advances to Contractors and Other	Advances to contractors and other consisted of the following at: December 31, 2018 2017 Advances to contractors 15,127,502 11,992,870 Prepaid expenses 1,196,218 4,385,449 Other miscellaneous advances and receivables 2,845,045 3,353,461 19,168,765 19,731,780

AMAK PROPERTY AND EQUIPMENT (Ta

AMAK PROPERTY AND EQUIPMENT (Tables)	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and Equipment	Plant, pipeline and equipment include the following at December 31: 2018 2017 (thousands of dollars) Platinum catalyst $ 1,612 $ 1,612 Catalyst 3,131 779 Land 5,428 5,428 Plant, pipeline and equipment 253,905 186,946 Construction in progress 4,343 50,996 Total plant, pipeline and equipment 268,419 245,761 Less accumulated depreciation (73,762 ) (63,240 ) Net plant, pipeline and equipment $ 194,657 $ 182,521
AMAK
Property, Plant and Equipment [Line Items]
Property and Equipment	Property and equipment, net consisted of the following at: December 31, 2018 2017 Buildings 191,041,157 191,041,157 Leasehold improvements 1,838,317 1,838,317 Heavy equipment 118,125,568 110,259,122 Motor vehicles 22,467,300 22,783,108 Civil works 15,662,671 15,582,921 Tailings dam 23,042,594 22,684,394 Plant and machinery 324,372,695 315,029,454 Mining assets – rehabilitation costs 98,894,826 98,894,826 Mining assets – underground development costs 267,128,896 254,832,012 Construction in progress 5,106,409 5,532,817 1,067,680,433 1,038,478,128 Less accumulated depreciation, depletion and amortization (432,824,358 ) (344,676,457 ) 634,856,075 693,801,671

AMAK DEVELOPMENT COSTS (Tables)

AMAK DEVELOPMENT COSTS (Tables)	12 Months Ended
	Dec. 31, 2018
AMAK
Schedule of Equity Method Investments [Line Items]
Development Costs, Net	Development costs, net consisted of the following at: December 31, 2018 2017 Cost 289,973,237 289,973,237 Accumulated amortization (134,691,712 ) (98,445,057 ) 155,281,525 191,528,180

AMAK ACCOUNTS PAYABLE, ACCRUE_2

AMAK ACCOUNTS PAYABLE, ACCRUED LIABILITIES AND FORGIVENESS OF LIABILITIES (Tables)	12 Months Ended
	Dec. 31, 2018
AMAK
Schedule of Equity Method Investments [Line Items]
Accounts Payable and Accrued Liabilities	Accounts payable and accrued liabilities consisted of the following at: December 31, 2018 2017 Accounts payable and accrued liabilities 26,925,170 17,858,012 Other 381,763 2,802,493 Accrued salaries and payroll expenses 1,450,012 2,012,113 28,756,945 22,672,618

AMAK ZAKAT AND INCOME TAX (Tabl

AMAK ZAKAT AND INCOME TAX (Tables)	12 Months Ended
	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Components of Income Tax Benefit (Expense)	The provision for income taxes consisted of the following: Year ended December 31, 2018 2017 2016 (thousands of dollars) Current federal provision (benefit) $ (74 ) $ (1,202 ) $ 1,691 Current state provision 31 282 18 Deferred federal provision (benefit) (974 ) (6,320 ) 8,645 Deferred state provision 210 81 150 Income tax expense (benefit) $ (807 ) $ (7,159 ) $ 10,504
Tax Effects of Temporary Differences	Tax effects of temporary differences that give rise to significant portions of federal and state deferred tax assets and deferred tax liabilities were as follows: December 31, 2018 2017 (thousands of dollars) Deferred tax liabilities: Plant, pipeline and equipment $ (25,169 ) $ (17,014 ) Intangible assets (1,075 ) (778 ) Other assets (40 ) (4 ) Investment in AMAK (671 ) (1,023 ) Total deferred tax liabilities $ (26,955 ) $ (18,819 ) Deferred tax assets: Accounts receivable 238 198 Inventory 133 156 Mineral interests 226 226 Foreign tax credit 802 — Net operating loss carryforward 9,073 — Post-retirement benefits 79 252 Stock-based compensation 954 971 Gross deferred tax assets 11,505 1,803 Valuation allowance (226 ) (226 ) Total net deferred tax assets $ 11,279 $ 1,577 Net deferred tax liabilities $ (15,676 ) $ (17,242 )
AMAK
Schedule of Equity Method Investments [Line Items]
Components of Income Tax Benefit (Expense)	The components of Zakat and income tax benefit (expense) are as follows: Years ended December 31, 2018 2017 2016 Deferred income tax benefit 12,961,569 8,617,706 6,694,909 Change in valuation allowance (5,736,640 ) (9,035,670 ) (8,413,167 ) Current Zakat and income tax expense (5,400,000 ) (3,209,229 ) (1,877,986 ) Zakat and income tax benefit (expense) 1,824,929 (3,627,193 ) (3,596,244 )
Tax Effects of Temporary Differences	Tax effects of temporary differences that give rise to significant portions of non-Saudi owners deferred tax assets and deferred tax liabilities were as follows: December 31, 2018 2017 Deferred tax assets: Loss carryforward 42,194 42,884 Other 657 469 42,851 43,352 Deferred tax liabilities: Property and Equipment (7,806 ) (21,236 ) Net deferred tax asset 35,045 22,116 Valuation allowance (38,837 ) (33,134 ) Net deferred tax liability (3,793 ) (11,018 )

AMAK LONG-TERM DEBT (Tables)

AMAK LONG-TERM DEBT (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Instrument [Line Items]
Repayment Schedule	Principal payments of long-term debt for the next five years and thereafter ending December 31 are as follows: Year Ending December 31, Long-Term Debt (thousands of dollars) 2019 4,375 2020 4,375 2021 4,375 2022 4,375 2023 85,812 Total 103,312
AMAK
Debt Instrument [Line Items]
Summary of Long-Term Debts	Long-term debts are summarized as follows at: December 31, 2018 2017 SIDF loan agreement 305,000,000 305,000,000 Deferred finance charges (8,741,288 ) (10,917,190 ) Total debt 296,258,712 294,082,810 Less current portion 30,000,000 65,000,000 Total long-term debt, less current portion 266,258,712 229,082,810
Repayment Schedule	The repayment schedule is as follows: Years Ending December 31, 2019 30,000,000 2020 50,000,000 2021 60,000,000 2022 60,000,000 2023 70,000,000 Thereafter 35,000,000 305,000,000

AMAK END-OF-SERVICE INDEMNITI_2

AMAK END-OF-SERVICE INDEMNITIES (Tables)	12 Months Ended
	Dec. 31, 2018
AMAK
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Change in End-of-Service Indemnities Provision	The change in the end-of-service indemnities provision is as follows: Years Ended December 31, 2018 2017 Balance, beginning of year 2,518,529 1,480,636 Provision for the year 1,347,418 1,375,024 Paid during the year (216,058 ) (337,131 ) Balance, end of year 3,649,889 2,518,529

AMAK ASSET RETIREMENT OBLIGAT_2

AMAK ASSET RETIREMENT OBLIGATIONS (Tables) - AMAK	12 Months Ended
	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Deferred Mine Closure Costs	Deferred mine closure costs consisted of the following at: December 31, 2018 2017 Cost 12,842,625 12,842,625 Accumulated amortization (6,886,626 ) (6,142,126 ) 5,955,999 6,700,499
Summary of Changes in Provision for Mine Closure Costs	A summary of changes in our provision for mine closure costs is as follows: Years Ended December 31, 2018 2017 2016 Balance, beginning of year 15,519,938 14,995,109 14,488,028 Accretion expense 543,198 524,829 507,081 Balance, end of year 16,063,136 15,519,938 14,995,109

AMAK GENERAL AND ADMINISTRATI_2

AMAK GENERAL AND ADMINISTRATIVE EXPENSES (Tables)	12 Months Ended
	Dec. 31, 2018
AMAK
Schedule of Equity Method Investments [Line Items]
Summary of General and Administrative Expenses	A summary of general and administrative expenses is as follows: Years Ended December 31, 2018 2017 2016 Wages, salaries and related costs 17,036,965 14,837,901 10,195,511 Mine closure and environmental 1,287,698 1,641,580 1,623,831 Office expenses 9,287,218 6,589,090 5,491,679 Travel and accommodation 593,046 2,958,938 1,477,413 Professional fees 1,271,071 2,272,224 8,169,121 29,475,998 28,299,733 26,957,555

AMAK COMMITMENTS AND CONTINGE_2

AMAK COMMITMENTS AND CONTINGENCIES (Tables)	12 Months Ended
	Dec. 31, 2018
Loss Contingencies [Line Items]
Schedule of Future Minimum Property and Equipment Lease Payments	Future minimum property and equipment lease payments under the non-cancelable operating leases at December 31, 2018 , are as follows: Year Ending December 31, (thousands of dollars) 2019 $ 3,670 2020 3,583 2021 3,418 2022 3,107 2023 2,288 Thereafter 2,065 Total $ 18,131
AMAK
Loss Contingencies [Line Items]
Schedule of Future Minimum Property and Equipment Lease Payments	A summary of these commitments are as follows: Years Ending December 31, 2019 990,000 2020 990,000 2021 990,000 2022 990,000 2023 550,000 Thereafter 1,650,000 6,160,000
Schedule of Future Minimum Lease Payments for Capital Leases	The future minimum lease payments under the capital lease obligations are as follows for the years ending December 31,: 2019 250,526 2020 250,526 2021 147,558 Total minimum lease payments 648,610 Less deferred financial charges (95,593 ) Total capital lease obligations 553,017 Less: current portion of capital lease obligations 193,206 Total long term portion, net current portion 359,811

BUSINESS AND OPERATIONS OF TH_2

BUSINESS AND OPERATIONS OF THE COMPANY (Details)	Dec. 31, 2018
AMAK
Noncontrolling Interest [Line Items]
Ownership Percentage	33.00%
PEVM
Noncontrolling Interest [Line Items]
Ownership Percentage	55.00%

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)	12 Months Ended
	Dec. 31, 2018USD ($)ر.س / $	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)account
Accounting Policies [Abstract]
Increase in allowance for doubtful accounts	$ 152,000	$ 0	$ 90,000
Receivable write-offs	$ 0	$ 0	$ 93,000
Number of accounts written off | account			1
Imputed interest rates on outstanding notes	4.00%	4.00%
Notes receivable allowance	$ 0	$ 0
Employer percent of match	100.00%
Employer percent match of gross pay	6.00%
Vesting period under 401(k) plan	2 years
Matching contributions on behalf of employees	$ 1,502,000	1,412,000	$ 1,195,000
Reduction in depreciation expense due to amortization of capitalize liability	$ 787,000	$ 840,000	$ 1,047,000
Foreign exchange rate (SR per USD) | ر.س / $	3.75
Undiscounted future minimum operating lease payments not recognized under current standard	$ 18,131,000

ACQUISITION OF B PLANT - Additi

ACQUISITION OF B PLANT - Additional Information (Details) $ in Thousands	May 02, 2016USD ($)a	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Business Acquisition [Line Items]
Cash paid in acquisition		$ 0	$ 0	$ 2,011
Bargain purchase gain		$ 0	$ 0	$ 11,549
BASF Facility
Business Acquisition [Line Items]
Cash paid in acquisition	$ 2,011
Acquisition transaction costs	11
Earnout provision based upon revenue	$ 1,800
Area of real estate | a	6.5
Bargain purchase gain	$ 11,549

ACQUISITION OF B PLANT - Purcha

ACQUISITION OF B PLANT - Purchase Price Allocation (Details) - USD ($) $ in Thousands	May 02, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Cash paid		$ 0	$ 0	$ 2,011
Estimated earnout liability		0	0	733
Fixed assets at FMV
Bargain purchase gain		$ 0	$ 0	$ 11,549
BASF Facility
Business Acquisition [Line Items]
Cash paid	$ 2,011
Estimated earnout liability	733
Purchase Price	2,744
Fixed assets at FMV
Land	980
Site improvements	30
Buildings	1,350
Production equipment	11,933
Total of Fixed assets at FMV	14,293
Bargain purchase gain	$ 11,549

CONCENTRATIONS OF REVENUES AN_2

CONCENTRATIONS OF REVENUES AND CREDIT RISK (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Concentration Risk [Line Items]
Accounts receivable	$ 27,112,000	$ 25,779,000
Amount owed to supplier for feedstock purchases	4,700,000	$ 8,500,000
FDIC insured amount	$ 250,000
Supplier Concentration Risk
Concentration Risk [Line Items]
Concentration risk	100.00%	100.00%	99.00%
Revenue | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk	17.00%	19.60%	20.10%
Revenue | Geographic Concentration Risk
Concentration Risk [Line Items]
Concentration risk	35.40%	20.80%	23.50%
Accounts Receivable
Concentration Risk [Line Items]
Accounts receivable	$ 11,000,000	$ 5,800,000

TRADE RECEIVABLES (Details)

TRADE RECEIVABLES (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Receivables [Abstract]
Trade receivables	$ 27,564	$ 26,079
Less allowance for doubtful accounts	(452)	(300)
Trade receivables, net	$ 27,112	$ 25,779

PREPAID EXPENSES AND OTHER AS_3

PREPAID EXPENSES AND OTHER ASSETS (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid license	$ 2,419	$ 1,919
Spare parts	1,597	954
Other prepaid expenses and assets	648	772
Total	$ 4,664	$ 3,645

INVENTORIES (Details)

INVENTORIES (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Raw material	$ 4,742	$ 3,703
Work in process	173	27
Finished products	11,624	14,720
Total inventory	16,539	18,450
Inventory products in transit	$ 4,100	$ 3,700

PLANT, PIPELINE AND EQUIPMENT_2

PLANT, PIPELINE AND EQUIPMENT (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Total plant, pipeline and equipment	$ 268,419	$ 245,761
Less accumulated depreciation	(73,762)	(63,240)
PLANT, PIPELINE, AND EQUIPMENT, NET	194,657	182,521
Interest capitalized for construction	731	937	$ 450
Capitalized labor costs	2,307	4,344	2,889
Amortization included in cost of sales	59	25	$ 98
Platinum catalyst
Property, Plant and Equipment [Line Items]
Total plant, pipeline and equipment	1,612	1,612
Catalyst
Property, Plant and Equipment [Line Items]
Total plant, pipeline and equipment	3,131	779
Land
Property, Plant and Equipment [Line Items]
Total plant, pipeline and equipment	5,428	5,428
Plant, pipeline and equipment
Property, Plant and Equipment [Line Items]
Total plant, pipeline and equipment	253,905	186,946
Construction in progress
Property, Plant and Equipment [Line Items]
Total plant, pipeline and equipment	$ 4,343	$ 50,996

GOODWILL AND INTANGIBLE ASSET_3

GOODWILL AND INTANGIBLE ASSETS, NET - Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Intangible assets subject to amortization (Definite-lived)
Intangible assets subject to amortization, Gross	$ 24,548	$ 24,548
Accumulated Amortization	(7,956)	(6,095)
Intangible assets subject to amortization, Net	16,592	18,453
Intangible assets not subject to amortization (Indefinite-lived)
Total, Gross	26,903	26,903
Total, Net	18,947	20,808
Amortization of intangible assets	1,861	1,861	$ 1,880
Emissions Allowance
Intangible assets not subject to amortization (Indefinite-lived)
Intangible assets not subject to amortization, Net	197	197
Trade name
Intangible assets not subject to amortization (Indefinite-lived)
Intangible assets not subject to amortization, Net	2,158	2,158
Customer relationships
Intangible assets subject to amortization (Definite-lived)
Intangible assets subject to amortization, Gross	16,852	16,852
Accumulated Amortization	(4,775)	(3,651)
Intangible assets subject to amortization, Net	12,077	13,201
Non-compete agreements
Intangible assets subject to amortization (Definite-lived)
Intangible assets subject to amortization, Gross	94	94
Accumulated Amortization	(80)	(61)
Intangible assets subject to amortization, Net	14	33
Licenses and permits
Intangible assets subject to amortization (Definite-lived)
Intangible assets subject to amortization, Gross	1,471	1,471
Accumulated Amortization	(495)	(390)
Intangible assets subject to amortization, Net	976	1,081
Developed technology
Intangible assets subject to amortization (Definite-lived)
Intangible assets subject to amortization, Gross	6,131	6,131
Accumulated Amortization	(2,606)	(1,993)
Intangible assets subject to amortization, Net	$ 3,525	$ 4,138

GOODWILL AND INTANGIBLE ASSET_4

GOODWILL AND INTANGIBLE ASSETS, NET - Expected Amortization Expense (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
2019	$ 1,856
2020	1,842
2021	1,837
2022	1,822
2023	1,822
Thereafter	7,413
Intangible assets subject to amortization, Net	16,592	$ 18,453
Customer relationships
Finite-Lived Intangible Assets [Line Items]
2019	1,123
2020	1,123
2021	1,123
2022	1,123
2023	1,123
Thereafter	6,462
Intangible assets subject to amortization, Net	12,077	13,201
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
2019	14
2020	0
2021	0
2022	0
2023	0
Thereafter	0
Intangible assets subject to amortization, Net	14	33
Licenses and permits
Finite-Lived Intangible Assets [Line Items]
2019	106
2020	106
2021	101
2022	86
2023	86
Thereafter	491
Intangible assets subject to amortization, Net	976	1,081
Developed technology
Finite-Lived Intangible Assets [Line Items]
2019	613
2020	613
2021	613
2022	613
2023	613
Thereafter	460
Intangible assets subject to amortization, Net	$ 3,525	$ 4,138

INVESTMENT IN AL MASANE AL KO_3

INVESTMENT IN AL MASANE AL KOBRA MINING COMPANY ("AMAK") (Details)	1 Months Ended		12 Months Ended
	Dec. 31, 2018USD ($)ر.س / $shares	Jul. 31, 2016USD ($)$ / sharesshares	Dec. 31, 2018USD ($)ر.س / $shares	Dec. 31, 2017USD ($)shares	Dec. 31, 2016USD ($)	Oct. 31, 2018shares	Jul. 31, 2016ر.س / sharesshares	Jul. 30, 2016
Schedule of Equity Method Investments [Line Items]
Foreign exchange rate (SR per USD) | ر.س / $	3.75		3.75
Results of Operations [Abstract]
Operating income (loss)			$ 2,335,000	$ 18,102,000	$ 18,707,000
Equity in Income or Loss of AMAK Reflected on Consolidated Statement Of Operation [Abstract]
Equity in loss of AMAK			(901,000)	(4,261,000)	(1,479,000)
Gain from equity issuance by AMAK			$ 0	$ 0	3,168,000
Common stock, shares outstanding (in shares) | shares	24,500,000		24,500,000	24,300,000
AMAK
Schedule of Equity Method Investments [Line Items]
Investment in AMAK	$ 38,700,000		$ 38,700,000	$ 45,100,000
Foreign exchange rate (SR per USD) | ر.س / $	3.75		3.75
Results of Operations [Abstract]
Sales			$ 70,234,000	36,435,000	9,921,000
Cost of sales			(68,084,000)	(43,304,000)	(27,132,000)
Gross loss			2,150,000	(6,869,000)	(17,211,000)
General, administrative and other expenses			8,879,000	9,903,000	9,690,000
Operating income (loss)			(6,729,000)	(16,772,000)	(26,901,000)
Gain on settlement with former operator			0	0	17,425,000
Net loss			(6,729,000)	(16,772,000)	(9,476,000)
Depreciation and amortization			33,469,000	22,419,000	11,672,000
Net income before depreciation and amortization			26,740,000	5,648,000	2,196,000
Equity Method Investment, Summarized Financial Information [Abstract]
Current assets	$ 44,093,000		44,093,000	23,333,000
Noncurrent assets	212,291,000		212,291,000	237,875,000
Total assets	256,384,000		256,384,000	261,208,000
Current liabilities	17,160,000		17,160,000	24,439,000
Long term liabilities	77,366,000		77,366,000	68,837,000
Shareholders' equity	161,858,000		161,858,000	167,932,000
Total liabilities and equity	$ 256,384,000		256,384,000	261,208,000
Equity in Income or Loss of AMAK Reflected on Consolidated Statement Of Operation [Abstract]
AMAK Net Loss			(6,729,000)	(16,772,000)	(9,476,000)
Zakat tax applicable to Saudi Arabian shareholders only			0	0	320,000
AMAK Net Loss before Saudi Arabian shareholders' portion of Zakat			(6,729,000)	(16,772,000)	(9,156,000)
Company's share of loss reported by AMAK (33.41% beginning July 10, 2016 and 35.25% prior to July 10, 2016)			(2,248,000)	(5,608,000)	(2,826,000)
Amortization of difference between Company's investment in AMAK and Company's share of net assets of AMAK			1,347,000	1,347,000	1,347,000
Equity in loss of AMAK			(901,000)	(4,261,000)	(1,479,000)
Gain upon formation of AMAK			$ 16,200,000
Issued to employees (in shares) | shares		4,000,000
Percentage investment in AMAK	100.00%	33.44%	100.00%				33.44%	35.25%
Gain from equity issuance by AMAK		$ 3,200,000
Stock exchanged during period (in shares) | shares			24,489
Approved repurchase amount (in shares) | shares						2,500,000
Return on investment	$ 5,300,000
Percentage of shares to be repurchased	10.00%
Common stock, shares outstanding (in shares) | shares	82,000,000		82,000,000
Amount receivable for unreimbursed travel expenses	$ 54,000		$ 54,000	121,000
Impairment charges recorded			$ 0	$ 0	$ 0
AMAK | Various Saudi shareholders
Equity in Income or Loss of AMAK Reflected on Consolidated Statement Of Operation [Abstract]
Percentage investment in AMAK	46.73%		46.73%
AMAK | Trecora Resources
Equity in Income or Loss of AMAK Reflected on Consolidated Statement Of Operation [Abstract]
Percentage investment in AMAK	33.41%		33.41%
AMAK | Armico
Equity in Income or Loss of AMAK Reflected on Consolidated Statement Of Operation [Abstract]
Percentage investment in AMAK	19.86%		19.86%
Arab Mining Co
Equity in Income or Loss of AMAK Reflected on Consolidated Statement Of Operation [Abstract]
Issued to employees (in shares) | shares		3,750,000
Share price (in SR and dollars per share) | (per share)		$ 5.33					ر.س 20.00
Reserved for future issuance (in shares) | shares		250,000					250,000
Treasury Stock
Equity in Income or Loss of AMAK Reflected on Consolidated Statement Of Operation [Abstract]
Stock exchanged during period (in shares) | shares			65,000

MINERAL PROPERTIES IN THE UNI_2

MINERAL PROPERTIES IN THE UNITED STATES (Details)	12 Months Ended
	Dec. 31, 2018aClaimT	Aug. 31, 2001Claim
Mineral Industries Disclosures [Abstract]
Number of patented mining claims in which PEVM has undivided interest	48
Number of unpatented mining claims in which PEVM has undivided interest	5
Area under patented and unpatented mining claims | a	1,500
Allocated mining capacity per day | T	300
Unpatented claims abandoned		75
Period when the property is unused	35 years

LONG-TERM DEBT AND LONG-TERM _3

LONG-TERM DEBT AND LONG-TERM OBLIGATIONS - Additional Information (Details)	Jul. 31, 2018USD ($)	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018USD ($)	Jul. 30, 2018USD ($)	Dec. 31, 2017USD ($)	Oct. 31, 2014USD ($)
Debt Instrument [Line Items]
Outstanding debt						$ 102,482,000		$ 99,082,000
Debt issuance costs						830,000		$ 501,000
ARC Agreement
Debt Instrument [Line Items]
Debt issuance costs						300,000
ARC Agreement | Revolving Credit Facility
Debt Instrument [Line Items]
Revolving commitments									$ 40,000,000
ARC Agreement, Fourth Amendment
Debt Instrument [Line Items]
Debt issuance costs						900,000
ARC Agreement, Fourth Amendment | Revolving Credit Facility
Debt Instrument [Line Items]
Revolving commitments	$ 75,000,000
Borrowed funds under the agreement						18,000,000
Available borrowings						$ 18,000,000
Effective interest rate						4.19%
ARC Agreement, Fourth Amendment | Minimum | Revolving Credit Facility
Debt Instrument [Line Items]
Commitment fee	0.20%
ARC Agreement, Fourth Amendment | Minimum | TOCCO
Debt Instrument [Line Items]
Consolidated leverage ratio						4.75
Consolidated fixed charge coverage ratio	1.15
ARC Agreement, Fourth Amendment | Minimum | LIBOR | Revolving Credit Facility
Debt Instrument [Line Items]
Basis spread on variable rate	1.25%
ARC Agreement, Fourth Amendment | Minimum | Base Rate | Revolving Credit Facility
Debt Instrument [Line Items]
Basis spread on variable rate	0.25%
ARC Agreement, Fourth Amendment | Maximum | Revolving Credit Facility
Debt Instrument [Line Items]
Commitment fee	0.375%
ARC Agreement, Fourth Amendment | Maximum | TOCCO
Debt Instrument [Line Items]
Consolidated leverage ratio						1
Consolidated fixed charge coverage ratio	1
ARC Agreement, Fourth Amendment | Maximum | LIBOR | Revolving Credit Facility
Debt Instrument [Line Items]
Basis spread on variable rate	2.50%
ARC Agreement, Fourth Amendment | Maximum | Base Rate | Revolving Credit Facility
Debt Instrument [Line Items]
Basis spread on variable rate	1.50%
Single Advance Term Loan | ARC Agreement
Debt Instrument [Line Items]
Aggregate amount									70,000,000
Multiple Advance Term Loan | ARC Agreement
Debt Instrument [Line Items]
Aggregate amount									$ 25
Term Loan | ARC Agreement
Debt Instrument [Line Items]
Outstanding debt							$ 60,400,000
Term Loan | ARC Agreement, Fourth Amendment
Debt Instrument [Line Items]
Aggregate amount	$ 87,500,000
Outstanding debt						$ 84,500,000
Optional increase in borrowing capacity	$ 50,000,000
Forecast | ARC Agreement, Fourth Amendment | Minimum | TOCCO
Debt Instrument [Line Items]
Consolidated leverage ratio		3.50	3.75	4	4.25
Forecast | ARC Agreement, Fourth Amendment | Maximum | TOCCO
Debt Instrument [Line Items]
Consolidated leverage ratio		1	1	1	1

LONG-TERM DEBT AND LONG-TERM _4

LONG-TERM DEBT AND LONG-TERM OBLIGATIONS - Principal Payments of Long-term Debt (Details) $ in Thousands	Dec. 31, 2018USD ($)
Debt Disclosure [Abstract]
2019	$ 4,375
2020	4,375
2021	4,375
2022	4,375
2023	85,812
Total debt	$ 103,312

LONG-TERM DEBT AND LONG-TERM _5

LONG-TERM DEBT AND LONG-TERM OBLIGATIONS - Components of Long-term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Jul. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Long-term debt, gross	$ 103,312
Loan fees	830		$ 501
Total debt	102,482		99,082
Less current portion	4,194		8,061
Total long-term debt, less current portion	98,288		91,021
ARC Agreement, Fourth Amendment
Debt Instrument [Line Items]
Loan fees	900
ARC Agreement
Debt Instrument [Line Items]
Loan fees	300
Term Loan | ARC Agreement, Fourth Amendment
Debt Instrument [Line Items]
Long-term debt, gross	85,312		47,250
Total debt	84,500
Term Loan | ARC Agreement
Debt Instrument [Line Items]
Total debt		$ 60,400
Acquisition Loan | ARC Agreement
Debt Instrument [Line Items]
Long-term debt, gross	0		17,333
Revolving Credit Facility | ARC Agreement, Fourth Amendment
Debt Instrument [Line Items]
Long-term debt, gross	$ 18,000		$ 35,000

ACCRUED LIABILITIES (Details)

ACCRUED LIABILITIES (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accrued Liabilities [Abstract]
Accrued state taxes	$ 210	$ 272
Accrued payroll	936	1,407
Accrued interest	31	30
Accrued officer compensation	0	500
Accrued restructuring & severance expenses (Note 21)	1,221	0
Accrued foreign taxes	802	0
Other liabilities	2,239	1,752
Total	$ 5,439	$ 3,961

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Additional Information (Details)	12 Months Ended
	Dec. 31, 2018USD ($)Railcar	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2018SAR (ر.س)Railcar	Dec. 31, 2017SAR (ر.س)	Oct. 24, 2010USD ($)	Oct. 24, 2010SAR (ر.س)
Guarantor Obligations [Line Items]
Undiscounted future minimum operating lease payments not recognized under current standard	$ 18,131,000
Rental expense of operating leases	4,400,000	$ 4,400,000	$ 4,200,000
Mine closure and environmental	$ 745,000	593,000	$ 622,000
Railroad Transportation Equipment
Guarantor Obligations [Line Items]
Number of railcars | Railcar	346			346
Undiscounted future minimum operating lease payments not recognized under current standard	$ 17,300,000
Term of lease commitment	9 years			9 years
Office Space in Sugar Land, TX
Guarantor Obligations [Line Items]
Undiscounted future minimum operating lease payments not recognized under current standard	$ 587,000
Other Machinery and Equipment
Guarantor Obligations [Line Items]
Undiscounted future minimum operating lease payments not recognized under current standard	207,000
Saudi Industrial Development Fund Limited Guarantee
Guarantor Obligations [Line Items]
Loan guarantee						41.00%	41.00%
Principal amount of loan guaranteed						$ 88,000,000	ر.س 330,000,000.0
Amount of maximum exposure	$ 81,300,000	$ 81,300,000		ر.س 305,000,000	ر.س 305,000,000	$ 36,100,000	ر.س 135,300,000

COMMITMENTS AND CONTINGENCIES_2

COMMITMENTS AND CONTINGENCIES - Future Minimum Property and Equipment Lease Payments (Details) $ in Thousands	Dec. 31, 2018USD ($)
Commitments and Contingencies Disclosure [Abstract]
2019	$ 3,670
2020	3,583
2021	3,418
2022	3,107
2023	2,288
Thereafter	2,065
Total	$ 18,131

SHARE-BASED COMPENSATION - Addi

SHARE-BASED COMPENSATION - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jun. 30, 2012	Jul. 31, 2008
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation	$ 1,753,000	$ 2,707,000	$ 2,552,000
Share-based compensation reclassified	318,000
Stock Option Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issuance (in shares)					1,000,000
Unrecognized compensation costs related to non-vested share-based compensation	$ 0
Stock Option Plans | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of expiration period	10 years
Granted (in shares)	0
Weighted average grant date fair value (in dollars per share)	$ 0	$ 0	$ 0
Proceeds from stock options exercised	$ 912,000	$ 25,000	$ 11,000
Shares issued upon option and warrant exercise (in shares)	268,000
Fair value of options vested in period	$ 1,533,000
Stock Option Plans | Stock Options and Warrants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issued during the period (in shares)	0	0	0
Intrinsic value of options and warrants exercised	$ 2,630,000	$ 164,000	$ 237,000
Exercised in period (in shares)	378,000
Stock Option Plans | Mr. Hatem El Khalidi | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation reclassified	$ 680,000	$ 0
Stock Option Plans | Common Stock | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options in the money (in shares)	500,000
The Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issuance (in shares)				1,500,000
The Plan | Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation costs related to non-vested restricted share-based compensation	$ 2,500,000
Weighted average period compensation cost expected to be recognized	1 year 10 months 24 days
Minimum | Stock Option Plans | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
Minimum | The Plan | Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	2 years 6 months
Maximum | Stock Option Plans | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	5 years
Maximum | The Plan | Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	5 years

SHARE-BASED COMPENSATION - Stoc

SHARE-BASED COMPENSATION - Stock Options and Warrant Awards (Details) - Stock Options and Warrants - Stock Option Plans $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)$ / sharesshares
Stock Options and Warrants
Outstanding at beginning of period (in shares) | shares	1,323,587
Granted (in shares) | shares	0
Expired (in shares) | shares	0
Exercised (in shares) | shares	(377,757)
Forfeited (in shares) | shares	(200,000)
Outstanding at end of period (in shares) | shares	745,830
Expected to vest (in shares) | shares	0
Exercisable (in shares) | shares	745,830
Weighted Average Exercise Price Per Share
Outstanding, beginning of period (in dollars per share) | $ / shares	$ 7.82
Granted (in dollars per share) | $ / shares	0
Expired (in dollars per share) | $ / shares	0
Exercised (in dollars per share) | $ / shares	5.21
Forfeited (in dollars per share) | $ / shares	3.40
Outstanding, end of period (in dollars per share) | $ / shares	10.33
Expected to vest (in dollars per share) | $ / shares	0
Exercisable (in dollars per share) | $ / shares	$ 10.33
Weighted Average Remaining Contractual Life
Outstanding, contractual life	4 years 7 months 6 days
Expected to vest, contractual life	0 days
Exercisable, contractual life	4 years 7 months 6 days
Intrinsic Value
Outstanding, intrinsic value | $	$ 0
Expected to vest, intrinsic value | $	0
Exercisable, intrinsic value | $	$ 0

SHARE-BASED COMPENSATION - Non-

SHARE-BASED COMPENSATION - Non-vested Options (Details) - Stock Option Plans - Stock Options - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Shares
Non-vested, beginning of period (in shares)	325,000
Granted (in shares)	0
Forfeited (in shares)	(200,000)
Vested (in shares)	(125,000)
Non-vested, end of period (in shares)	0	325,000
Weighted Average Grant-Date Fair Value Per Share
Non-vested, at beginning of period (in dollars per share)	$ 6.81
Granted (in dollars per share)	0	$ 0	$ 0
Forfeited (in dollars per share)	3.40
Vested (in dollars per share)	12.26
Non-vested, end of period (in dollars per share)	$ 0	$ 6.81

SHARE-BASED COMPENSATION - Rest

SHARE-BASED COMPENSATION - Restricted Stock and Restricted Stock Unit Awards (Details) - The Plan - Restricted Stock Units	12 Months Ended
	Dec. 31, 2018$ / sharesshares
Shares of Restricted Stock Units
Outstanding, beginning of period (in shares)	387,702
Granted (in shares)	226,908
Forfeited (in shares)	(103,637)
Vested (in shares)	(105,298)
Outstanding, end of period (in shares)	405,675
Expected to vest (in shares)	405,675
Weighted Average Grant Date Price per Share
Outstanding, beginning of period (in dollars per share) | $ / shares	$ 11.39
Granted (in dollars per share) | $ / shares	11.45
Forfeited (in dollars per share) | $ / shares	11.39
Vested (in dollars per share) | $ / shares	11.99
Outstanding, end of period (in dollars per share) | $ / shares	$ 11.27

INCOME TAXES (Details)

INCOME TAXES (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2018
Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal provision (benefit)	$ (74,000)	$ (1,202,000)	$ 1,691,000
Current state provision	31,000	282,000	18,000
Deferred federal provision (benefit)	(974,000)	(6,320,000)	8,645,000
Deferred state provision	210,000	81,000	150,000
Zakat and income tax benefit (expense)	$ (807,000)	(7,159,000)	10,504,000
Income tax expense or liability in Saudi Arabia		$ 0	$ 0	$ 802,000
Income taxes at U.S. statutory rate	21.00%	35.00%	35.00%
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income taxes at U.S. statutory rate	$ (822,000)	$ 3,885,000	$ 10,476,000
State taxes, net of federal benefit	234,000	235,000	285,000
Net operating loss carryback	0	(961,000)	0
Research and development credits	(263,000)	0	0
Permanent and other items	44,000	(11,000)	(257,000)
Deferred tax impact of US tax reform	0	(10,307,000)	0
Zakat and income tax benefit (expense)	(807,000)	(7,159,000)	$ 10,504,000
Deferred tax liabilities:
Plant, pipeline and equipment	(25,169,000)	(17,014,000)
Intangible assets	(1,075,000)	(778,000)
Other assets	(40,000)	(4,000)
Investment in AMAK	(671,000)	(1,023,000)
Total deferred tax liabilities	(26,955,000)	(18,819,000)
Deferred tax assets:
Accounts receivable	238,000	198,000
Inventory	133,000	156,000
Mineral interests	226,000	226,000
Foreign tax credit	802,000	0
Net operating loss carryforward	9,073,000	0
Post-retirement benefits	79,000	252,000
Stock-based compensation	954,000	971,000
Gross deferred tax assets	11,505,000	1,803,000
Valuation allowance	(226,000)	(226,000)
Total net deferred tax assets	11,279,000	1,577,000
Net deferred tax liabilities	(15,676,000)	(17,242,000)
Change in valuation allowance		0
Interest or penalties related to uncertain tax positions	$ 0	$ 0
Scenario, Plan
Income Tax Expense (Benefit), Continuing Operations [Abstract]
Income taxes at U.S. statutory rate	21.00%

SEGMENT INFORMATION (Details)

SEGMENT INFORMATION (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2018USD ($)Segment	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | Segment									2
Net revenues	$ 74,669	$ 73,416	$ 68,106	$ 71,741	$ 65,978	$ 61,508	$ 62,115	$ 55,542	$ 287,932	$ 245,143	$ 212,399
Operating profit (loss) before depreciation and amortization									16,695	29,063
Operating profit (loss)									2,335	18,102	18,707
Profit (loss) before taxes									(3,139)	10,850	$ 29,932
Depreciation and amortization									14,358	10,961
Capital expenditures									25,285	14,053
Goodwill and intangible assets, net	40,745				42,606				40,745	42,606
Total assets	329,968				327,326				329,968	327,326
Corporate
Segment Reporting Information [Line Items]
Net revenues									0	0
Operating profit (loss) before depreciation and amortization									(8,275)	(7,413)
Operating profit (loss)									(8,327)	(7,475)
Profit (loss) before taxes									(9,184)	(11,764)
Depreciation and amortization									50	62
Capital expenditures									0	0
Goodwill and intangible assets, net	0				0				0	0
Total assets	91,474				97,880				91,474	97,880
Eliminations
Segment Reporting Information [Line Items]
Goodwill and intangible assets, net	0				0				0	0
Total assets	(161,239)				(153,346)				(161,239)	(153,346)
Specialty Petrochemical | Operating Segments
Segment Reporting Information [Line Items]
Net revenues									249,679	210,381
Operating profit (loss) before depreciation and amortization									23,021	36,511
Operating profit (loss)									14,089	30,201
Profit (loss) before taxes									10,705	27,852
Depreciation and amortization									8,932	6,310
Capital expenditures									22,431	38
Goodwill and intangible assets, net	0				0				0	0
Total assets	284,367				265,213				284,367	265,213
Specialty Wax | Operating Segments
Segment Reporting Information [Line Items]
Net revenues									38,253	34,762
Operating profit (loss) before depreciation and amortization									1,949	(35)
Operating profit (loss)									(3,427)	(4,624)
Profit (loss) before taxes									(4,660)	(5,238)
Depreciation and amortization									5,376	4,589
Capital expenditures									2,854	14,015
Goodwill and intangible assets, net	40,745				42,606				40,745	42,606
Total assets	$ 115,366				$ 117,579				$ 115,366	$ 117,579

NET INCOME (LOSS) PER COMMON _3

NET INCOME (LOSS) PER COMMON SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Net income (loss)									$ (2,332)	$ 18,009	$ 19,428
Basic earnings (loss) per common share:
Weighted average shares outstanding (in shares)									24,438,000	24,294,000	24,284,000
Per share amount (in dollars per share)	$ (0.22)	$ (0.07)	$ 0.09	$ 0.10	$ 0.58	$ 0.07	$ 0.03	$ 0.06	$ (0.10)	$ 0.74	$ 0.80
Diluted earnings (loss) per common share:
Weighted average shares outstanding (in shares)									24,438,000	25,129,000	24,982,000
Per share amount (in dollars per share)	$ (0.22)	$ (0.07)	$ 0.09	$ 0.09	$ 0.56	$ 0.07	$ 0.03	$ 0.06	$ (0.10)	$ 0.72	$ 0.78
Weighted average shares outstanding (in shares)									24,438,000	24,294,000	24,284,000
Unvested restricted stock unit grant (in shares)									0	367,000	310,000
Effect of dilutive stock options (in shares)									0	468,000	388,000
Weighted average shares, as adjusted denominator diluted computation (in shares)									24,438,000	25,129,000	24,982,000
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common stock shares issuable (in shares)									745,830	1,323,587	1,348,437
Restricted Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common stock shares issuable (in shares)									397
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common stock shares issuable (in shares)									264
Treasury Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock exchanged during period (in shares)									65,000
AMAK
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock exchanged during period (in shares)									24,489

QUARTERLY RESULTS OF OPERATIO_3

QUARTERLY RESULTS OF OPERATIONS (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 74,669	$ 73,416	$ 68,106	$ 71,741	$ 65,978	$ 61,508	$ 62,115	$ 55,542	$ 287,932	$ 245,143	$ 212,399
Gross profit	2,694	6,842	8,142	10,140	9,966	9,870	11,107	10,618	27,818	41,561	39,902
Net income (loss)	$ (5,290)	$ (1,609)	$ 2,215	$ 2,352	$ 13,972	$ 1,718	$ 832	$ 1,487	$ (2,332)	$ 18,009	$ 19,428
Basic EPS (in dollars per share)	$ (0.22)	$ (0.07)	$ 0.09	$ 0.10	$ 0.58	$ 0.07	$ 0.03	$ 0.06	$ (0.10)	$ 0.74	$ 0.80
Diluted EPS (in dollars per share)	$ (0.22)	$ (0.07)	$ 0.09	$ 0.09	$ 0.56	$ 0.07	$ 0.03	$ 0.06	$ (0.10)	$ 0.72	$ 0.78
Change in tax rate, income tax benefit					$ 10,300

RELATED PARTY TRANSACTIONS (Det

RELATED PARTY TRANSACTIONS (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Company Director
Related Party Transaction [Line Items]
Consulting fees	$ 28,000	$ 27,000	$ 33,000
Outstanding liability payable	0	0
Chairman of the Board
Related Party Transaction [Line Items]
Consulting fees	94,000	74,000	$ 73,000
Outstanding liability payable	$ 0	$ 0
Period of consulting agreement	3 years

RESTRUCTURING AND SEVERANCE E_2

RESTRUCTURING AND SEVERANCE EXPENSES (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restructuring Cost and Reserve [Line Items]
Restructuring and severance expenses	$ 2,347	$ 0	$ 0
Accounts Payable and Accrued Liabilities
Restructuring Cost and Reserve [Line Items]
Amount of restructuring that remains unpaid	$ 1,200

POST-RETIREMENT OBLIGATIONS (De

POST-RETIREMENT OBLIGATIONS (Details) - Postretirement Benefits - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Jun. 30, 2018
Mr. Hatem El Khalidi
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Deferred compensation arrangement with individual, amount of post-retirement obligation outstanding		$ 1,000	$ (1,000)
Chief Executive Officer
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Deferred compensation arrangement with individual, amount of post-retirement obligation outstanding	$ 377	249
Defined benefit plan, benefits paid	$ 18	$ 16

VALUATION AND QUALIFYING ACCO_2

VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-09, Valuation Allowance, Deferred Tax Asset
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	$ 225,622	$ 376,037	$ 376,037
Charged (credited) to earnings	0	(150,415)	0
Deductions	0	0	0
Ending balance	225,622	225,622	376,037
SEC Schedule, 12-09, Allowance, Credit Loss
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning balance	300,000	300,000	210,000
Charged (credited) to earnings	152,000	0	183,339
Deductions	0	0	(93,339)
Ending balance	$ 452,000	$ 300,000	$ 300,000

AMAK FINANCIAL STATEMENTS - Bal

AMAK FINANCIAL STATEMENTS - Balance Sheets (Details)	Dec. 31, 2018USD ($)	Dec. 31, 2018SAR (ر.س)	Dec. 31, 2017USD ($)	Dec. 31, 2017SAR (ر.س)	Dec. 31, 2016USD ($)	Dec. 31, 2016SAR (ر.س)	Dec. 31, 2015USD ($)	Dec. 31, 2015SAR (ر.س)
Current assets:
Cash and cash equivalents | $	$ 6,735,000		$ 3,028,000		$ 8,389,000		$ 18,623,000
Accounts receivable | $	27,112,000		25,779,000
Inventories | $	16,539,000		18,450,000
Total current assets | $	55,232,000		56,486,000
Non-current assets:
Property and equipment, net | $	194,657,000		182,521,000
TOTAL ASSETS | $	329,968,000		327,326,000
Current liabilities:
Zakat and income tax liability | $	210,000		272,000
Capital lease obligation, current portion | $	193,206
Long-term debt, current portion | $	4,194,000		8,061,000
Total current liabilities | $	29,491,000		31,544,000
Non-current liabilities
Capital lease obligation, net of current portion | $	359,811
Long-term debt, net of current portion and deferred finance costs | $	98,288,000		91,021,000
Deferred income taxes | $	15,676,000		17,242,000
Commitments and contingencies (Note 14) | $
Shareholders' equity
Share capital | $	2,463,000		2,451,000
Share premium | $	58,294,000		56,012,000
Accumulated deficit | $	124,123,000		126,455,000
Total Trecora Resources Stockholders' Equity | $	184,872,000		184,722,000
TOTAL LIABILITIES AND EQUITY | $	$ 329,968,000		$ 327,326,000
AMAK
Current assets:
Cash and cash equivalents		ر.س 31,510,496		ر.س 32,325,537		ر.س 56,518,906		ر.س 30,413,832
Accounts receivable		16,235,035		8,213,816
Inventories		45,871,120		27,226,932
Advances to shareholders (Note 1)		52,562,028		0
Advances to contractors and other		19,168,765		19,731,780
Total current assets		165,347,444		87,498,065
Non-current assets:
Property and equipment, net		634,856,075		693,801,671
Development costs, net		155,281,525		191,528,180
Deferred mine closure costs		5,955,999		6,700,499
Total non-current assets		796,093,599		892,030,350
TOTAL ASSETS		961,441,043		979,528,415
Current liabilities:
Accounts payable and accrued liabilities		28,756,945		22,672,618
Zakat and income tax liability		5,400,000		3,516,673
Due to shareholders		0		453,816
Capital lease obligation, current portion		193,206		0
Long-term debt, current portion		30,000,000		65,000,000
Total current liabilities		64,350,151		91,643,107
Non-current liabilities
Provision for mine closure costs		16,063,136		15,519,938		14,995,109		ر.س 14,488,028
Capital lease obligation, net of current portion		359,811		0
Long-term debt, net of current portion and deferred finance costs		266,258,712		229,082,810
End-of-service indemnities		3,649,889		2,518,529		ر.س 1,480,636
Deferred income taxes		3,792,785		11,017,714
Total non-current liabilities		290,124,333		258,138,991
Shareholders' equity
Share capital		820,000,000		780,000,000
Share premium		0		37,546,000
Accumulated deficit		(213,033,000)		(187,800,000)
Total Trecora Resources Stockholders' Equity		606,967,000		629,746,000
TOTAL LIABILITIES AND EQUITY		ر.س 961,441,000		ر.س 979,528,000

AMAK FINANCIAL STATEMENTS - Sta

AMAK FINANCIAL STATEMENTS - Statements of Operations (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2018SAR (ر.س)	Dec. 31, 2017USD ($)	Dec. 31, 2017SAR (ر.س)	Dec. 31, 2016USD ($)	Dec. 31, 2016SAR (ر.س)
Schedule of Equity Method Investments [Line Items]
Revenues | $	$ 74,669	$ 73,416	$ 68,106	$ 71,741	$ 65,978	$ 61,508	$ 62,115	$ 55,542	$ 287,932		$ 245,143		$ 212,399
Costs of revenues | $									260,114		203,582		172,497
Gross Profit | $	2,694	6,842	8,142	10,140	9,966	9,870	11,107	10,618	27,818		41,561		39,902
General and administrative expenses | $									22,396		22,587		20,434
Operating income (loss) | $									2,335		18,102		18,707
Other income (expense)
Finance charges | $									(4,100)		(2,931)		(1,985)
Total other income (expense) | $									(5,474)		(7,252)		11,225
Income (loss) before income tax expense | $									(3,139)		10,850		29,932
Zakat and income tax benefit (expense) | $									807		7,159		(10,504)
Net income (loss) attributable to Trecora Resources | $	$ (5,290)	$ (1,609)	$ 2,215	$ 2,352	$ 13,972	$ 1,718	$ 832	$ 1,487	$ (2,332)		$ 18,009		$ 19,428
AMAK
Schedule of Equity Method Investments [Line Items]
Revenues										ر.س 263,377,273		ر.س 136,629,881		ر.س 37,202,504
Costs of revenues										255,313,296		162,388,373		101,743,839
Gross Profit										8,063,977		(25,758,492)		(64,541,335)
General and administrative expenses										29,475,998		28,299,733		26,957,555
Operating income (loss)										(21,412,021)		(54,058,225)		(91,498,890)
Other income (expense)
Gain on forgiveness of liabilities and spare parts										0		0		65,345,250
Finance charges										(5,969,821)		(6,103,680)		(6,043,410)
Other income										323,575		893,524		260,953
Total other income (expense)										(5,646,246)		(5,210,156)		59,562,793
Income (loss) before income tax expense										(27,058,267)		(59,268,381)		(31,936,097)
Zakat and income tax benefit (expense)										1,824,929		(3,627,193)		(3,596,244)
Net income (loss) attributable to Trecora Resources										ر.س (25,233,338)		ر.س (62,895,574)		ر.س (35,532,341)

AMAK FINANCIAL STATEMENTS - S_2

AMAK FINANCIAL STATEMENTS - Statements of Changes in Shareholders' Equity (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)	Dec. 31, 2018SAR (ر.س)	Dec. 31, 2017USD ($)	Dec. 31, 2017SAR (ر.س)	Dec. 31, 2016USD ($)	Dec. 31, 2016SAR (ر.س)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance | $	$ 185,011		$ 164,376		$ 142,385
Issuance of share capital and premium | $	284		(36)		11
Net loss | $	(2,332)		18,009		19,428
Balance | $	185,161		185,011		164,376
Share Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance | $	2,451		2,451		2,416
Issuance of share capital and premium | $	2				3
Balance | $	2,463		2,451		2,451
Share Premium
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance | $	56,012		53,474		50,662
Issuance of share capital and premium | $	127		(92)		(8)
Balance | $	58,294		56,012		53,474
Retained Earnings (Accumulated Deficit)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance | $	126,455		108,446		89,018
Net loss | $	(2,332)		18,009		19,428
Balance | $	$ 124,123		$ 126,455		$ 108,446
AMAK
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance		ر.س 629,746,317		ر.س 692,641,891		ر.س 650,627,812
Issuance of share capital and premium		2,453,580				77,546,420
Net loss		(25,233,338)		(62,895,574)		(35,532,341)
Conversion of share premium to share capital		0
Balance		606,966,559		629,746,317		692,641,891
AMAK | Share Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance		780,000,000		780,000,000		740,000,000
Issuance of share capital and premium						40,000,000
Conversion of share premium to share capital		40,000,000
Balance		820,000,000		780,000,000		780,000,000
AMAK | Share Premium
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance		37,546,420		37,546,420		0
Issuance of share capital and premium		2,453,580				37,546,420
Conversion of share premium to share capital		(40,000,000)
Balance		0		37,546,420		37,546,420
AMAK | Retained Earnings (Accumulated Deficit)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance		(187,800,103)		(124,904,529)		(89,372,188)
Net loss		(25,233,338)		(62,895,574)		(35,532,341)
Balance		ر.س (213,033,441)		ر.س (187,800,103)		ر.س (124,904,529)

AMAK FINANCIAL STATEMENTS - S_3

AMAK FINANCIAL STATEMENTS - Statements of Cash Flows (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2018SAR (ر.س)	Dec. 31, 2017USD ($)	Dec. 31, 2017SAR (ر.س)	Dec. 31, 2016USD ($)	Dec. 31, 2016SAR (ر.س)
Cash flows from operating activities:
Net income (loss) | $	$ (5,290)	$ (1,609)	$ 2,215	$ 2,352	$ 13,972	$ 1,718	$ 832	$ 1,487	$ (2,332)		$ 18,009		$ 19,428
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Amortization of deferred finance costs | $									261		247		272
Changes in operating assets and liabilities:
Accounts receivable | $									(1,485)		(3,586)		(2,809)
Inventories | $									1,911		(579)		(2,067)
Accounts payable and accrued liabilities | $									2,240		6,983		3,168
Net cash provided by operating activities | $									19,895		30,828		28,514
Cash flows from investing activities:
Additions to property and equipment | $									(25,285)		(51,584)		(38,484)
Cash flows from financing activities:
Issuance of share capital and premium | $									0		25		11
Payments on long-term debt | $									(15,354)		(10,417)		(6,250)
Net cash provided by in financing activities | $									3,683		15,502		1,761
Net increase (decrease) in cash and cash equivalents | $									3,707		(5,361)		(10,234)
Cash and cash equivalents at beginning of year | $				$ 3,028				$ 8,389	3,028		8,389		18,623
Cash and cash equivalents at end of year | $	$ 6,735				$ 3,028				6,735		3,028		8,389
Supplemental cash flow information
Cash paid for interest | $									4,560		3,540		2,545
Cash paid for Zakat and income tax | $									$ (4,182)		$ 92		$ (1,630)
AMAK
Cash flows from operating activities:
Net income (loss)										ر.س (25,233,338)		ر.س (62,895,574)		ر.س (35,532,341)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization										125,507,864		83,547,586		43,768,238
Accretion of deferred mine closure costs										543,198		524,829		507,081
Amortization of deferred finance costs										2,175,902		1,610,733		2,147,644
Gain on forgiveness of liabilities										0		0		(65,345,250)
Deferred income taxes										(7,224,929)		417,966		1,718,258
Changes in operating assets and liabilities:
Accounts receivable										(8,021,219)		(8,213,816)		28,351,618
Inventories										(18,644,188)		(11,351,752)		15,754,952
Advances to contractors and other										563,016		(3,944,995)		(6,186,357)
Accounts payable and accrued liabilities										6,084,327		9,638,009		3,511,632
Zakat and income tax liability										1,883,327		1,583,048		679,206
Pre-export advance payment										0		0		(9,150,880)
End-of-service indemnities										1,131,360		1,037,893		(264,797)
Net cash provided by operating activities										78,765,320		11,953,927		(20,040,996)
Cash flows from investing activities:
Additions to property and equipment										(28,945,309)		(31,550,443)		(29,246,001)
Cash flows from financing activities:
Issuance of share capital and premium										2,453,580		0		75,092,840
Payments on capital lease obligations										(72,788)		0		0
Payments on long-term debt										0		(5,000,000)		0
Net advances from (to) shareholders										(53,015,844)		403,147		299,231
Net cash provided by in financing activities										(50,635,052)		(4,596,853)		75,392,071
Net increase (decrease) in cash and cash equivalents										(815,041)		(24,193,369)		26,105,074
Cash and cash equivalents at beginning of year										32,325,537		56,518,906		30,413,832
Cash and cash equivalents at end of year										31,510,496		32,325,537		56,518,906
Supplemental cash flow information
Cash paid for interest										3,927,778		3,686,000		3,895,766
Cash paid for Zakat and income tax										3,212,813		1,626,179		1,198,780
Supplemental disclosure of non-cash items
Assets acquired through capital lease obligations										ر.س 625,805		ر.س 0		ر.س 0

AMAK ORGANIZATION AND BUSINES_2

AMAK ORGANIZATION AND BUSINESS - Narrative (Details)	May 22, 1993SAR (ر.س)km²	Dec. 31, 2018SAR (ر.س)shipmentshares	Dec. 31, 2017SAR (ر.س)shipmentshares	Dec. 31, 2016SAR (ر.س)ر.س / sharesshares	Dec. 31, 2015SAR (ر.س)shares	Dec. 31, 2013SAR (ر.س)ر.س / sharesshares	Dec. 31, 2011SAR (ر.س)ر.س / sharesshares	Oct. 31, 2018ر.س / sharesshares	Dec. 31, 2009SAR (ر.س)share_bundleshares
Schedule of Equity Method Investments [Line Items]
Authorized capital (in shares) | shares		40,000,000	40,000,000
Issued capital (in shares) | shares		24,600,000	24,500,000
AMAK
Schedule of Equity Method Investments [Line Items]
Authorized capital (in shares) | shares									450,000,000
Authorized capital, number of share bundles | share_bundle									45,000,000
Authorized capital, number of shares per bundle | shares		10		10	10	10	10		10
Capital issued for cash (as a percent)									50.00%
Capital issued for contribution of mining rights and assets (as a percent)									50.00%
Increase to authorized share capital (SR)		ر.س 40,000,000		ر.س 40,000,000	ر.س 190,000,000	ر.س 50,000,000	ر.س 50,000,000
Authorized share capital (SR)		ر.س 820,000,000		ر.س 780,000,000	ر.س 740,000,000	ر.س 550,000,000	ر.س 500,000,000
Issued capital (in shares) | shares		4,000,000		4,000,000	19,000,000	5,000,000	5,000,000
Price per share (SR per share) | ر.س / shares				ر.س 20		ر.س 30	ر.س 28
Share premium (SR)				ر.س 35,092,840		ر.س 100,000,000	ر.س 90,000,000
Increase to share premium for shares that were previously issued (SR)		ر.س 2,453,580
Approved repurchase amount (in shares) | shares								2,500,000
Approved repurchase price (SR per share) | ر.س / shares								ر.س 30
Advances to shareholders (SR)		ر.س 52,562,028	ر.س 0
Number of shipments of ore generated during the period | shipment		4	2
Trecora | Loan payable | Loan due to the Ministry of Finance and National Economy
Schedule of Equity Method Investments [Line Items]
Aggregate amount									ر.س 41,250,000
Trecora | Al Masane mine
Schedule of Equity Method Investments [Line Items]
Mining rights, term	30 years
Mining rights, renewal period	20 years
Area of mine (in square kilometers) | km²	44
Surface rental per square kilometer per year	ر.س 10,000
Surface rental per year	ر.س 440,000

AMAK ORGANIZATION AND BUSINES_3

AMAK ORGANIZATION AND BUSINESS - Schedule of Ownership in Joint Stock Company (Details) - AMAK	Dec. 31, 2018shares
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	33.00%
Saudi shareholders,Trecora, and ARMICO
Schedule of Equity Method Investments [Line Items]
Shares	82,000,000
Ownership Percentage	100.00%
Saudi shareholders
Schedule of Equity Method Investments [Line Items]
Shares	38,349,184
Ownership Percentage	46.80%
Trecora (US Company)
Schedule of Equity Method Investments [Line Items]
Shares	27,402,876
Ownership Percentage	33.40%
ARMICO (Pan Arab Organization)
Schedule of Equity Method Investments [Line Items]
Shares	16,247,940
Ownership Percentage	19.80%

AMAK SUMMARY OF SIGNIFICANT A_2

AMAK SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) ر.س in Thousands	12 Months Ended
	Dec. 31, 2018SAR (ر.س)ر.س / $	Dec. 31, 2017SAR (ر.س)	Dec. 31, 2016SAR (ر.س)	Jun. 30, 1986
Property, Plant and Equipment [Line Items]
Foreign exchange rate (SR per USD) | ر.س / $	3.75
AMAK
Property, Plant and Equipment [Line Items]
Interest rate on pre-export advances	2.50%
Operating lease expense | ر.س	ر.س 1,619	ر.س 1,454	ر.س 442
Zakat tax rate	2.50%
Non-Saudi tax rate	20.00%
AMAK | Riyals
Property, Plant and Equipment [Line Items]
Foreign exchange rate (SR per USD)				3.75
AMAK | Other assets | Minimum
Property, Plant and Equipment [Line Items]
Useful life	3 years
AMAK | Other assets | Maximum
Property, Plant and Equipment [Line Items]
Useful life	20 years

AMAK LIQUIDITY AND CAPITAL RE_2

AMAK LIQUIDITY AND CAPITAL RESOURCES (Details) - AMAK	12 Months Ended
	Dec. 31, 2018year
Schedule of Equity Method Investments [Line Items]
Number of consecutive years of net losses	3
Mining assets – rehabilitation costs
Schedule of Equity Method Investments [Line Items]
Extension to life of mine	2 years

AMAK INVENTORIES (Details)

AMAK INVENTORIES (Details) $ in Thousands	Dec. 31, 2018USD ($)	Dec. 31, 2018SAR (ر.س)	Dec. 31, 2017USD ($)	Dec. 31, 2017SAR (ر.س)
Inventory [Line Items]
Inventories | $	$ 16,539		$ 18,450
AMAK
Inventory [Line Items]
Inventories		ر.س 45,871,120		ر.س 27,226,932
AMAK | Ore concentrates
Inventory [Line Items]
Inventories		17,020,657		12,118,132
AMAK | Stockpile ore
Inventory [Line Items]
Inventories		19,134,297		9,417,626
AMAK | Precious metal dore
Inventory [Line Items]
Inventories		2,159,192		0
AMAK | Explosives
Inventory [Line Items]
Inventories		1,134,728		485,668
AMAK | Chemicals and other
Inventory [Line Items]
Inventories		ر.س 6,422,246		ر.س 5,205,506

AMAK ADVANCES TO CONTRACTORS _3

AMAK ADVANCES TO CONTRACTORS AND OTHER (Details) - AMAK - SAR (ر.س)	Dec. 31, 2018	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Advances to contractors	ر.س 15,127,502	ر.س 11,992,870
Prepaid expenses	1,196,218	4,385,449
Other miscellaneous advances and receivables	2,845,045	3,353,461
Advances to contractors and other	ر.س 19,168,765	ر.س 19,731,780

AMAK PROPERTY AND EQUIPMENT (De

AMAK PROPERTY AND EQUIPMENT (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)	Dec. 31, 2018SAR (ر.س)	Dec. 31, 2017USD ($)	Dec. 31, 2017SAR (ر.س)	Dec. 31, 2016SAR (ر.س)	Dec. 31, 2018SAR (ر.س)	Dec. 31, 2017SAR (ر.س)
Property, Plant and Equipment [Line Items]
Property and equipment, gross | $	$ 268,419		$ 245,761
Less accumulated depreciation | $	(73,762)		(63,240)
PLANT, PIPELINE, AND EQUIPMENT, NET | $	194,657		182,521
Depreciation, depletion and amortization expense | $	14,358		10,961
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross | $	$ 4,343		$ 50,996
AMAK
Property, Plant and Equipment [Line Items]
Property and equipment, gross						ر.س 1,067,680,433	ر.س 1,038,478,128
Less accumulated depreciation						(432,824,358)	(344,676,457)
PLANT, PIPELINE, AND EQUIPMENT, NET						634,856,075	693,801,671
Depreciation, depletion and amortization expense		ر.س 88,000,000		ر.س 64,300,000	ر.س 0
AMAK | Buildings
Property, Plant and Equipment [Line Items]
Property and equipment, gross						191,041,157	191,041,157
AMAK | Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross						1,838,317	1,838,317
AMAK | Heavy equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross						118,125,568	110,259,122
AMAK | Motor vehicles
Property, Plant and Equipment [Line Items]
Property and equipment, gross						22,467,300	22,783,108
AMAK | Civil works
Property, Plant and Equipment [Line Items]
Property and equipment, gross						15,662,671	15,582,921
AMAK | Tailings dam
Property, Plant and Equipment [Line Items]
Property and equipment, gross						23,042,594	22,684,394
AMAK | Plant and machinery
Property, Plant and Equipment [Line Items]
Property and equipment, gross						324,372,695	315,029,454
AMAK | Mining assets – rehabilitation costs
Property, Plant and Equipment [Line Items]
Property and equipment, gross						98,894,826	98,894,826
AMAK | Mining assets – underground development costs
Property, Plant and Equipment [Line Items]
Property and equipment, gross						267,128,896	254,832,012
AMAK | Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross						ر.س 5,106,409	ر.س 5,532,817

AMAK DEVELOPMENT COSTS (Details

AMAK DEVELOPMENT COSTS (Details) - AMAK - SAR (ر.س)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Cost	ر.س 289,973,237	ر.س 289,973,237
Accumulated amortization	(134,691,712)	(98,445,057)
Development costs, net	155,281,525	191,528,180
Amortization expenses related to development costs	ر.س 36,250,000	ر.س 18,200,000

AMAK ACCOUNTS PAYABLE, ACCRUE_3

AMAK ACCOUNTS PAYABLE, ACCRUED LIABILITIES AND FORGIVENESS OF LIABILITIES (Details) $ in Thousands	Mar. 31, 2016SAR (ر.س)	Dec. 31, 2018USD ($)	Dec. 31, 2018SAR (ر.س)	Dec. 31, 2017USD ($)	Dec. 31, 2017SAR (ر.س)
Schedule of Equity Method Investments [Line Items]
Other | $		$ 733		$ 870
Spare parts included in property and equipment, net on the balance sheets | $		1,597		954
Total amounts of liabilities recorded | $		$ 144,807		$ 142,315
AMAK
Schedule of Equity Method Investments [Line Items]
Accounts payable and accrued liabilities			ر.س 26,925,170		ر.س 17,858,012
Other			381,763		2,802,493
Accrued salaries and payroll expenses			1,450,012		2,012,113
Accounts payable and accrued liabilities			ر.س 28,756,945		ر.س 22,672,618
Payment received by CGM for rights to spare parts	ر.س 4,500,000
Economic value of forfeited spare parts	34,477,500
Spare parts included in property and equipment, net on the balance sheets	4,500,000
Total amounts of liabilities recorded	ر.س 65,345,000

AMAK ZAKAT AND INCOME TAX - Com

AMAK ZAKAT AND INCOME TAX - Components of Income Tax Benefit (Expense) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)	Dec. 31, 2018SAR (ر.س)	Dec. 31, 2017USD ($)	Dec. 31, 2017SAR (ر.س)	Dec. 31, 2016USD ($)	Dec. 31, 2016SAR (ر.س)
Income Tax Disclosure [Line Items]
Deferred income tax benefit | $	$ 1,566		$ 5,841		$ (8,697)
Zakat and income tax benefit (expense) | $	$ (807)		$ (7,159)		$ 10,504
AMAK
Income Tax Disclosure [Line Items]
Deferred income tax benefit		ر.س 12,961,569		ر.س 8,617,706		ر.س 6,694,909
Change in valuation allowance		(5,736,640)		(9,035,670)		(8,413,167)
Current Zakat and income tax expense		(5,400,000)		(3,209,229)		(1,877,986)
Zakat and income tax benefit (expense)		ر.س (1,824,929)		ر.س 3,627,193		ر.س 3,596,244

AMAK ZAKAT AND INCOME TAX - Nar

AMAK ZAKAT AND INCOME TAX - Narrative (Details) - AMAK - SAR (ر.س) ر.س in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Line Items]
Statutory rate for non-Saudi shareholders	20.00%
Tax loss carryforwards	ر.س 210,970	ر.س 214,418

AMAK ZAKAT AND INCOME TAX - Tax

AMAK ZAKAT AND INCOME TAX - Tax Effects of Temporary Differences (Details) ر.س in Thousands, $ in Thousands	Dec. 31, 2018USD ($)	Dec. 31, 2018SAR (ر.س)	Dec. 31, 2017USD ($)	Dec. 31, 2017SAR (ر.س)
Deferred tax assets:
Loss carryforward | $	$ 9,073		$ 0
Gross deferred tax assets | $	11,505		1,803
Deferred tax liabilities:
Property and Equipment | $	(25,169)		(17,014)
Valuation allowance | $	(226)		(226)
Net deferred tax liabilities | $	$ (15,676)		$ (17,242)
AMAK
Deferred tax assets:
Loss carryforward		ر.س 42,194		ر.س 42,884
Other		657		469
Gross deferred tax assets		42,851		43,352
Deferred tax liabilities:
Property and Equipment		(7,806)		(21,236)
Net deferred tax asset		35,045		22,116
Valuation allowance		(38,837)		(33,134)
Net deferred tax liabilities		ر.س (3,793)		ر.س (11,018)

AMAK LONG-TERM DEBT - Narrative

AMAK LONG-TERM DEBT - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)	Dec. 31, 2018SAR (ر.س)	Dec. 31, 2017USD ($)	Dec. 31, 2017SAR (ر.س)	Dec. 31, 2016USD ($)	Dec. 31, 2016SAR (ر.س)	Dec. 31, 2018SAR (ر.س)	Dec. 31, 2017SAR (ر.س)	Dec. 31, 2010SAR (ر.س)
Debt Instrument [Line Items]
Loan fees | $	$ 830		$ 501
Amortization of loan fees | $	$ 261		$ 247		$ 272
AMAK
Debt Instrument [Line Items]
Loan fees							ر.س 8,741,288	ر.س 10,917,190
Amortization of loan fees		ر.س 2,175,902		ر.س 1,610,733		ر.س 2,147,644
Secured Debt | Loan agreement with SIDF | AMAK
Debt Instrument [Line Items]
Collateralized loan agreement									ر.س 330,000,000
Loan fees							ر.س 8,741,288	ر.س 10,917,190
Amortization of loan fees		ر.س 1,639,000		ر.س 1,611,000		ر.س 2,148,000

AMAK LONG-TERM DEBT - Summary o

AMAK LONG-TERM DEBT - Summary of Long-Term Debts (Details) $ in Thousands	Dec. 31, 2018USD ($)	Dec. 31, 2018SAR (ر.س)	Dec. 31, 2017USD ($)	Dec. 31, 2017SAR (ر.س)
Debt Instrument [Line Items]
SIDF loan agreement | $	$ 103,312
Deferred finance charges | $	(830)		$ (501)
Total debt | $	102,482		99,082
Less current portion | $	4,194		8,061
Total long-term debt, less current portion | $	$ 98,288		$ 91,021
AMAK
Debt Instrument [Line Items]
SIDF loan agreement | ر.س		ر.س 305,000,000		ر.س 305,000,000
Deferred finance charges | ر.س		(8,741,288)		(10,917,190)
Total debt | ر.س		296,258,712		294,082,810
Less current portion | ر.س		30,000,000		65,000,000
Total long-term debt, less current portion | ر.س		ر.س 266,258,712		ر.س 229,082,810

AMAK LONG-TERM DEBT - Repayment

AMAK LONG-TERM DEBT - Repayment Schedule (Details) $ in Thousands	Dec. 31, 2018USD ($)	Dec. 31, 2018SAR (ر.س)	Dec. 31, 2017SAR (ر.س)
Years Ending December 31,
2019 | $	$ 4,375
2020 | $	4,375
2021 | $	4,375
2022 | $	4,375
2023 | $	85,812
Total debt | $	$ 103,312
AMAK
Years Ending December 31,
2019		ر.س 30,000,000
2020		50,000,000
2021		60,000,000
2022		60,000,000
2023		70,000,000
Thereafter		35,000,000
Total debt		ر.س 305,000,000	ر.س 305,000,000

AMAK END-OF-SERVICE INDEMNITI_3

AMAK END-OF-SERVICE INDEMNITIES (Details) - AMAK - SAR (ر.س)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
End-Of-Service Indemnities [Roll Forward]
Balance, beginning of year	ر.س 2,518,529	ر.س 1,480,636
Provision for the year	1,347,418	1,375,024
Paid during the year	(216,058)	(337,131)
Balance, end of year	ر.س 3,649,889	ر.س 2,518,529

AMAK ASSET RETIREMENT OBLIGAT_3

AMAK ASSET RETIREMENT OBLIGATIONS - Narrative (Details) - AMAK - SAR (ر.س) ر.س in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2012
Schedule of Equity Method Investments [Line Items]
ARO recorded for deferred mine closure costs				ر.س 12,843
Amortization expense	ر.س 745	ر.س 1,117	ر.س 1,117

AMAK ASSET RETIREMENT OBLIGAT_4

AMAK ASSET RETIREMENT OBLIGATIONS - Deferred Mine Closure Costs (Details) - AMAK - SAR (ر.س)	Dec. 31, 2018	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Cost	ر.س 12,842,625	ر.س 12,842,625
Accumulated amortization	(6,886,626)	(6,142,126)
Deferred mine closure costs, net	ر.س 5,955,999	ر.س 6,700,499

AMAK ASSET RETIREMENT OBLIGAT_5

AMAK ASSET RETIREMENT OBLIGATIONS - Summary of Changes in Provision for Mine Closure Costs (Details) - AMAK - SAR (ر.س)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance, beginning of year	ر.س 15,519,938	ر.س 14,995,109	ر.س 14,488,028
Accretion expense	543,198	524,829	507,081
Balance, end of year	ر.س 16,063,136	ر.س 15,519,938	ر.س 14,995,109

AMAK GENERAL AND ADMINISTRATI_3

AMAK GENERAL AND ADMINISTRATIVE EXPENSES (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)	Dec. 31, 2018SAR (ر.س)	Dec. 31, 2017USD ($)	Dec. 31, 2017SAR (ر.س)	Dec. 31, 2016USD ($)	Dec. 31, 2016SAR (ر.س)
Schedule of Equity Method Investments [Line Items]
Mine closure and environmental | $	$ 745		$ 593		$ 622
General and administrative expenses | $	$ 22,396		$ 22,587		$ 20,434
AMAK
Schedule of Equity Method Investments [Line Items]
Wages, salaries and related costs		ر.س 17,036,965		ر.س 14,837,901		ر.س 10,195,511
Mine closure and environmental		1,287,698		1,641,580		1,623,831
Office expenses		9,287,218		6,589,090		5,491,679
Travel and accommodation		593,046		2,958,938		1,477,413
Professional fees		1,271,071		2,272,224		8,169,121
General and administrative expenses		ر.س 29,475,998		ر.س 28,299,733		ر.س 26,957,555

AMAK COMMITMENTS AND CONTINGE_3

AMAK COMMITMENTS AND CONTINGENCIES - Operating Lease Obligations (Details)	Dec. 31, 2018USD ($)
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2019	$ 3,670,000
2020	3,583,000
2021	3,418,000
2022	3,107,000
2023	2,288,000
Thereafter	2,065,000
Total	$ 18,131,000
Mining assets – rehabilitation costs
Operating Leased Assets [Line Items]
Term of lease commitment	30 years
Term of lease renewal	20 years
Guyan | Mining assets – rehabilitation costs
Operating Leased Assets [Line Items]
Term of lease commitment	20 years
AMAK
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2019	$ 990,000
2020	990,000
2021	990,000
2022	990,000
2023	550,000
Thereafter	1,650,000
Total	$ 6,160,000

AMAK COMMITMENTS AND CONTINGE_4

AMAK COMMITMENTS AND CONTINGENCIES - Capital Lease Obligations (Details)	Dec. 31, 2018USD ($)
Commitments and Contingencies Disclosure [Abstract]
2019	$ 250,526
2020	250,526
2021	147,558
Total minimum lease payments	648,610
Less deferred financial charges	(95,593)
Total capital lease obligations	553,017
Less: current portion of capital lease obligations	193,206
Total long term portion, net current portion	$ 359,811