Southern Copper (SCCO) 10-Q 1 Nov 21 2021 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2021	Nov. 01, 2021
Document and Entity Information
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2021
Document Transition Report	false
Entity File Number	1-14066
Entity Registrant Name	SOUTHERN COPPER CORP/
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	13-3849074
Entity Address, Address Line One	1440 East Missouri Avenue Suite 160
Entity Address, City or Town	Phoenix
Entity Address, State or Province	AZ
Entity Address, Postal Zip Code	85014
City Area Code	602
Local Phone Number	264-1375
Title of 12(b) Security	Common stock
Trading Symbol	SCCO
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		773,081,269
Entity Central Index Key	0001001838
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Amendment Flag	false

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF EARNINGS - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
CONDENSED CONSOLIDATED STATEMENTS OF EARNINGS
Net sales (including sales to related parties, see note 5)	$ 2,680.9	$ 2,129.1	$ 8,110.4	$ 5,634.2
Operating cost and expenses:
Cost of sales (exclusive of depreciation, amortization and depletion shown separately below)	927.5	948.9	2,856.8	2,881.3
Selling, general and administrative	31.3	33.4	92.9	94
Depreciation, amortization and depletion	203.4	196	599.4	582.8
Exploration	10.9	6.9	26.7	21.8
Total operating costs and expenses	1,173.1	1,185.2	3,575.8	3,579.9
Operating income	1,507.8	943.9	4,534.6	2,054.3
Interest expense	(96.7)	(96.7)	(290)	(296.6)
Capitalized interest	7.8	7.5	22.2	18.7
Other income (expense)	(1.9)	(14)	(7.8)	(22.4)
Interest income	1.5	2.8	5.2	14.9
Income before income taxes	1,418.5	843.5	4,264.2	1,768.9
Income taxes (including royalty taxes, see Note 4)	548.6	338.5	1,703.8	784.7
Net income before equity earnings of affiliate	869.9	505	2,560.4	984.2
Equity earnings of affiliate, net of income tax	1.3	3.1	14.4	1
Net income	871.2	508.1	2,574.8	985.2
Less: Net income attributable to the non-controlling interest	3.6	2.1	10.6	4.9
Net income attributable to SCC	$ 867.6	$ 506	$ 2,564.2	$ 980.3
Per common share amounts attributable to SCC:
Net earnings-basic and diluted	$ 1.12	$ 0.65	$ 3.32	$ 1.27
Weighted average shares outstanding-basic and diluted	773.1	773.1	773.1	773.1

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
Net income and comprehensive income	$ 871.2	$ 508.1	$ 2,574.8	$ 985.2
-Derivative instruments classified as cash flow hedge:
- Unrealized gain of the period (net of income tax of $2.7 million in 2021)	6.4		6.4
Total other comprehensive income	6.4		6.4
Total comprehensive income	877.6	508.1	2,581.2	985.2
Comprehensive income attributable to the non-controlling interest	3.6	2.1	10.6	4.9
Comprehensive income attributable to SCC	$ 874	$ 506	$ 2,570.6	$ 980.3

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parentheticals) $ in Millions	9 Months Ended
	Sep. 30, 2021USD ($)
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
Unrealized gain of the period tax	$ 2.7

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 2,583.7	$ 2,183.6
Short-term investments	626.8	410.8
Accounts receivable trade	1,493.4	1,068.9
Accounts receivable other (including related parties 2021- $34.6 and 2020 - $23.3)	86.4	67.7
Inventories	912.5	950.2
Prepaid taxes	134.1	104.8
Other current assets	53.9	29.2
Total current assets	5,890.8	4,815.2
Property and mine development, net	9,476.1	9,458.7
Ore stockpiles on leach pads	1,171.1	1,125
Intangible assets, net	139	143
Right-of-use assets	926.6	979
Deferred income tax	286.7	230
Equity method investment	120.5	114.3
Other non-current assets	99.5	81.3
Total assets	18,110.3	16,946.5
Current liabilities:
Accounts payable (including related parties 2021- $112.7 and 2020- $104.3)	611.2	594.6
Accrued income taxes	654.9	340.9
Accrued workers' participation	279.6	247.8
Accrued interest	131.2	98.6
Lease liabilities current	72.6	70.6
Other accrued liabilities	39.6	32.3
Total current liabilities	1,789.1	1,384.8
Long-term debt	6,546.7	6,544.2
Lease liabilities	854	908.4
Deferred income taxes	118.4	159.4
Other liabilities and reserves	89.1	128.7
Asset retirement obligation	559.6	545
Total non-current liabilities	8,167.8	8,285.7
Commitments and contingencies (Note 10)
STOCKHOLDERS' EQUITY (NOTE 11)
Common stock par value $0.01; shares authorized, 2021 and 2020-2,000; shares issued, 2021 and 2020-884.6	8.8	8.8
Additional paid-in capital	3,460.2	3,441.5
Retained earnings	7,709.8	6,846.4
Accumulated other comprehensive income (loss)	(2)	(8.4)
Treasury stock, at cost, common shares	(3,080.8)	(3,063.5)
Total Southern Copper Corporation stockholders' equity	8,096	7,224.8
Non-controlling interest	57.4	51.2
Total equity	8,153.4	7,276
Total liabilities and equity	$ 18,110.3	$ 16,946.5

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) shares in Millions, $ in Millions	Sep. 30, 2021	Dec. 31, 2020
CONDENSED CONSOLIDATED BALANCE SHEETS
Accounts receivable other, related parties	$ 34.6	$ 23.3
Accounts payable, related parties	$ 112.7	$ 104.3
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	2,000	2,000
Common stock, shares issued	884.6	884.6

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
OPERATING ACTIVITIES
Net income	$ 871.2	$ 508.1	$ 2,574.8	$ 985.2
Adjustments to reconcile net earnings to net cash provided from operating activities:
Depreciation, amortization and depletion	203.4	196	599.4	582.8
Equity earnings of affiliate, net of dividends received	2.8	(3.1)	(6.3)	(3.9)
(Gain) loss on foreign currency transaction effect	(36.6)	4.1	(50)	(24.8)
Benefit for deferred income taxes	(103.3)	(45.9)	(100.1)	(57.2)
Other, net	5.1	4.2	16.9	15.2
Change in operating assets and liabilities:
Increase in accounts receivable	(57.7)	(101.6)	(424.5)	(122.6)
(Increase) decrease in inventories	(9.5)	(0.6)	(8.3)	155.8
Increase in accounts payable and accrued liabilities	332.3	268.2	409.5	99.3
Decrease (increase) in other operating assets and liabilities	12.9	(35.9)	53.3	58.2
Net cash provided by operating activities	1,220.6	793.5	3,064.7	1,688
INVESTING ACTIVITIES
Capital expenditures	(243.1)	(134.5)	(695.5)	(348.8)
Proceeds from (purchase) sale of short-term investments, net	(81)		(216)	50
Other	9.9	0.8	(0.6)	1.2
Net cash used in investing activities	(314.2)	(133.7)	(912.1)	(297.6)
FINANCING ACTIVITIES
Repayments of debt				(400)
Capitalization of debt issuance cost				0.1
Cash dividends paid to common stockholders	(695.8)	(309.2)	(1,700.8)	(773.1)
Other, net	(1.6)	0.3	(4.3)	(2.1)
Net cash used in financing activities	(697.4)	(308.9)	(1,705.1)	(1,175.1)
Effect of exchange rate changes on cash and cash equivalents	(19.6)	(14.3)	(47.4)	5
Increase in cash and cash equivalents	189.4	336.6	400.1	220.3
Cash and cash equivalents, at beginning of period	2,394.3	1,808.8	2,183.6	1,925.1
Cash and cash equivalents, at end of period	$ 2,583.7	$ 2,145.4	$ 2,583.7	$ 2,145.4

CONDENSED CONSOLIDATED STATEM_5

CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) $ in Millions	CAPITAL STOCK:	ADDITIONAL PAID-IN CAPITAL:	TREASURY STOCK:Southern Copper common shares	TREASURY STOCK:Parent Company common shares	TREASURY STOCK:	RETAINED EARNINGS:	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS):	STOCKHOLDERS' EQUITY	NON-CONTROLLING INTEREST	Total
Balance at beginning of year at Dec. 31, 2019	$ 8.8	$ 3,424.9	$ (2,767.9)	$ (281)		$ 6,435.6	$ (10.1)	$ 6,810.3	$ 47.9	$ 6,858.2
Increase (Decrease) in Stockholders' Equity
Net earnings						980.3			4.9	980.3
Dividends declared and paid, common stock, per share, 2021- '$2.20, 2020- '$1.00						(773.1)			(2.8)
Used for corporate purposes			0.4
Other activity, including dividend, interest and foreign currency transaction effect				0.5
Other activity of the period		0.8
Balance at end of year at Sep. 30, 2020		3,425.7	(2,767.5)	(280.5)	$ (3,048)	6,642.8	(10.1)	7,019.2	50	7,069.2
Balance at beginning of year at Jun. 30, 2020	8.8	3,418.2	(2,767.9)	(273.6)		6,446.1	(10.1)	6,821.5	48.1	6,869.6
Increase (Decrease) in Stockholders' Equity
Net earnings						506			2.1	506
Dividends declared and paid, common stock, per share, 2021- '$2.20, 2020- '$1.00						(309.2)			(0.2)
Used for corporate purposes			0.4
Other activity, including dividend, interest and foreign currency transaction effect				(6.9)
Other activity of the period		7.5				(0.1)
Balance at end of year at Sep. 30, 2020		3,425.7	(2,767.5)	(280.5)	(3,048)	6,642.8	(10.1)	7,019.2	50	7,069.2
Balance at beginning of year at Dec. 31, 2020	8.8	3,441.5	(2,767.5)	(296)		6,846.4	(8.4)	7,224.8	51.2	7,276
Increase (Decrease) in Stockholders' Equity
Net earnings						2,564.2			10.6	2,564.2
Dividends declared and paid, common stock, per share, 2021- '$2.20, 2020- '$1.00						(1,700.8)			(4.4)
Used for corporate purposes			0.1
Other activity, including dividend, interest and foreign currency transaction effect				(17.4)
Other activity of the period		18.7
Other comprehensive income (loss)							6.4			6.4
Balance at end of year at Sep. 30, 2021		3,460.2	(2,767.4)	(313.4)	(3,080.8)	7,709.8	(2)	8,096	57.4	8,153.4
Balance at beginning of year at Jun. 30, 2021	$ 8.8	3,454.9	(2,767.4)	(308.4)		7,538	(8.4)	7,917.5	55.3	7,972.8
Increase (Decrease) in Stockholders' Equity
Net earnings						867.6			3.6	867.6
Dividends declared and paid, common stock, per share, 2021- '$2.20, 2020- '$1.00						(695.8)			(1.5)
Other activity, including dividend, interest and foreign currency transaction effect				(5)
Other activity of the period		5.3
Other comprehensive income (loss)							6.4			6.4
Balance at end of year at Sep. 30, 2021		$ 3,460.2	$ (2,767.4)	$ (313.4)	$ (3,080.8)	$ 7,709.8	$ (2)	$ 8,096	$ 57.4	$ 8,153.4

CONDENSED CONSOLIDATED STATEM_6

CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (Parenthetical) - $ / shares	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY
Dividends paid as cash dividend (in dollars per share)	$ 2.20	$ 1

DESCRIPTION OF THE BUSINESS_

DESCRIPTION OF THE BUSINESS:	9 Months Ended
	Sep. 30, 2021
DESCRIPTION OF THE BUSINESS:
DESCRIPTION OF THE BUSINESS:	Southern Copper Corporation ​ NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS (Unaudited) ​ NOTE 1— DESCRIPTION OF THE BUSINESS: ​ The Company is a majority-owned, indirect subsidiary of Grupo Mexico S.A.B. de C.V. (“Grupo Mexico”). As of September 30, 2021, Grupo Mexico, through its wholly-owned subsidiary Americas Mining Corporation (“AMC”) owned 88.9% of the Company’s capital stock. The condensed consolidated financial statements presented herein consist of the accounts of Southern Copper Corporation (“Southern Copper”, "SCC" or the “Company”), a Delaware corporation, and its subsidiaries. The Company is an integrated producer of copper and other minerals, and operates mining, smelting and refining facilities in Peru and Mexico. The Company conducts its primary operations in Peru through a registered branch (the "Peruvian Branch" or “Branch” or “SPCC Peru Branch”). The Peruvian Branch is not a corporation separate from the Company. The Company's Mexican operations are conducted through subsidiaries. The Company also conducts exploration activities in Argentina, Chile, Ecuador, Mexico and Peru. ​ In the opinion of the Company, the accompanying unaudited condensed consolidated financial statements contain all adjustments (consisting only of normal recurring adjustments) necessary to fairly state the Company’s financial position as of September 30, 2021 and the results of operations, comprehensive income, cash flows and changes in equity for the three and nine months ended September 30, 2021 and 2020. The results of operations for the nine months ended September 30, 2021 are not necessarily indicative of the results to be expected for the full year. The December 31, 2020 balance sheet data was derived from audited financial statements, but does not include all disclosures required by generally accepted accounting principles in the United States of America (“GAAP”). The accompanying condensed consolidated financial statements should be read in conjunction with the consolidated financial statements at December 31, 2020 and notes included in the Company’s 2020 annual report on Form 10-K. ​ COVID – 19 PANDEMIC ​ Since the World Health Organization (“WHO”) declared the COVID-19 virus outbreak as a global pandemic, all the countries where the Company operates and conducts exploration activities, as well as the countries where its main customers and suppliers are located, have published health and safety rules and restrictions on individuals and business activities. ​ As of September 30, 2021, the Company‘s production facilities in Mexico and Peru were working at approximately 96% of their production capacity. The Company has developed a rigorous COVID-19 emergency protocol and the workforce is gradually returning to work at all of our facilities. As of September 30, 2021, approximately 96% of the workforce in Mexico and 71% of the workforce in Peru was working on site or at home under strict safety measures; the remaining labor force was not working, including all individuals at high risk due to age and/or preexisting medical conditions. ​ The Company has fully restored exploration activities at all of its locations, except in Argentina where the Company is developing social and environmental programs for local communities. ​ The financial reporting process and the information required to prepare the Company’s financial statements suffered no interruption and the financial statements were prepared without restrictions or difficulties. ​ SCC´s Corporate Crisis Committee as well as its Crisis Committees in Mexico and Peru continue to closely monitor the impact of the pandemic and to analyze and quickly resolve any issues that may arise. As of September 30, 2021, the strong global economic recovery has generated significant challenges for the global shipping industry, which have led to congestion at ports, shortage of containers and a lack of space on ships. This situation has caused the Company to experience some delays in the reception of imported materials as well as in the shipment of its products and receivable collections. This, however, has had no material impact on the financial position of the Company. ​ After having completed the first stage of its capital programs at Buenavista in Mexico and Toquepala in Peru, the Company currently has no pending major capital expenditure s ​ The Company performed a qualitative analysis and as of September 30, 2021, identified no indicators of impairment. As the Company reported in its 2020 Annual report on Form 10-K, the results of its impairment sensitivity analysis showed projected discounted cash flows in excess of the carrying amounts of long-lived assets by margins ranging from 1.3 to 4.3 times such carrying amount. This analysis included a stress test using a copper price assumption of $2.00 per pound and a molybdenum price assumption of $4.00 per pound. (Please see, Management´s Discussion and Analysis, Critical Policies and Estimates, Asset Impairments on the 2020 Form 10-K). ​

SHORT-TERM INVESTMENTS_

SHORT-TERM INVESTMENTS:	9 Months Ended
	Sep. 30, 2021
SHORT-TERM INVESTMENTS:
SHORT-TERM INVESTMENTS:	NOTE 2 — SHORT-TERM INVESTMENTS: ​ Short-term investments were as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ At September 30, ​ At December 31, ​ ​ ​ 2021 2020 ​ ​ Trading securities ​ $ 626.4 ​ $ 410.2 ​ ​ Weighted average interest rate ​ 0.2 % 0.4 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available-for-sale ​ $ 0.4 ​ $ 0.6 ​ ​ Weighted average interest rate ​ 0.7 % 0.7 % ​ Total ​ $ 626.8 ​ $ 410.8 ​ ​ ​ Trading securities consist of bonds issued by public companies and are publicly traded. Each financial instrument is independent of the others. The Company has the intention to sell these bonds in the short-term. ​ Available-for-sale investments consist of securities issued by public companies. Each security is independent of the others and as of September 30, 2021 and December 31, 2020, included corporate bonds and asset and mortgage backed obligations. As of September 30, 2021 and December 31, 2020, gross unrealized gains and losses on available-for-sale securities were not material. ​ The Company earned interest related to these investments, which was recorded as interest income in the condensed consolidated statement of earnings. Also, the Company redeemed some of these securities and recognized gains (losses) due to changes in fair value, which were recorded as other income (expense) in the condensed consolidated statement of earnings. ​ The following table summarizes the activity of these investments by category (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Nine months ended ​ ​ ​ September 30, ​ September 30, ​ ​ ​ 2021 2020 2021 2020 ​ Trading: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest earned ​ $ 0.6 ​ $ (*) ​ $ 1.3 ​ $ 0.1 ​ ​ Unrealized gain (loss) at the end of the period ​ $ (*) ​ $ (*) ​ $ (*) ​ $ (*) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available-for-sale: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest earned ​ ​ (*) ​ ​ (*) ​ (*) ​ ​ (*) ​ ​ Investment redeemed ​ $ 0.1 ​ $ — ​ $ 0.2 ​ $ 0.1 ​ ​ (*) Less than $0.1 million.

INVENTORIES_

INVENTORIES:	9 Months Ended
	Sep. 30, 2021
INVENTORIES:
INVENTORIES:	NOTE 3 — INVENTORIES: ​ Inventories were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ At September 30, ​ At December 31, ​ (in millions) 2021 2020 ​ Inventory, current: ​ ​ ​ ​ ​ ​ ​ Metals at average cost: ​ ​ ​ ​ ​ ​ ​ Finished goods ​ $ 61.3 ​ $ 50.8 ​ Work-in-process ​ 278.1 ​ 248.9 ​ Ore stockpiles on leach pads ​ ​ 231.0 ​ ​ 298.5 ​ Supplies at average cost ​ 342.1 ​ 352.0 ​ Total current inventory ​ $ 912.5 ​ $ 950.2 ​ Inventory, long-term: ​ ​ ​ ​ ​ ​ ​ Ore stockpiles on leach pads ​ $ 1,171.1 ​ $ 1,125.0 ​ ​ ​ During the nine months ended September 30, 2021 and 2020, total leaching costs capitalized as non-current inventory of ore stockpiles on leach pads amounted to $184.2 million and $144.0 million, respectively. Leaching inventories recognized in cost of sales amounted to $205.7 million and $287.3 million for the nine months ended September 30, 2021 and 2020, respectively.

INCOME TAXES_

INCOME TAXES:	9 Months Ended
	Sep. 30, 2021
INCOME TAXES:
INCOME TAXES:	NOTE 4 — INCOME TAXES: ​ The income tax provision and the effective income tax rate for the first nine months of 2021 and 2020 consisted of (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ 2021 2020 ​ Statutory income tax provision ​ $ 1,387.0 ​ $ 694.7 ​ Peruvian royalty ​ 70.1 ​ 14.1 ​ Mexican royalty ​ 162.5 ​ 44.1 ​ Peruvian special mining tax ​ 84.2 ​ 31.8 ​ Total income tax provision ​ $ 1,703.8 ​ $ 784.7 ​ ​ ​ ​ ​ ​ ​ ​ ​ Effective income tax rate ​ ​ 40.0 % ​ 44.4 % ​ These provisions include income taxes for Peru, Mexico and the United States. The Mexican royalty, the Peruvian royalty and the Peruvian special mining tax are included in the income tax provision. The decrease in the effective income tax rate in 2021 compared to the same period in 2020 was primarily attributable to a movement in exchange gains and losses from the strong depreciation of the Mexican peso against the U.S. dollar in 2020. ​ Peruvian royalty and special mining tax ​ The Company has accrued $84.2 million and $31.8 million of special mining tax as part of the income tax provision for the first nine months of 2021 and 2020, respectively. ​ Mexican mining royalty ​ Accounting for uncertainty in income taxes: The Company effectively settled the 2014 through 2016 IRS audit on April 14, 2021. The decrease in unrecognized tax benefits from the audit settlement had no material effect on the Company’s financial statements.

RELATED PARTY TRANSACTIONS_

RELATED PARTY TRANSACTIONS:	9 Months Ended
	Sep. 30, 2021
RELATED PARTY TRANSACTIONS:
RELATED PARTY TRANSACTIONS:	NOTE 5 — RELATED PARTY TRANSACTIONS: ​ The Company has entered into certain transactions in the ordinary course of business with parties that are controlling shareholders or their affiliates. These transactions include the lease of office space, air and railroad transportation, construction services, energy supply, and other products and services related to mining and refining. The Company lends and borrows funds among affiliates for acquisitions and other corporate purposes. These financial transactions bear interest and are subject to review and approval by senior management, as are all related party transactions. Article Nine of the Amended and Restated Certificate of Incorporation of the Company prohibits the Company from engaging in a Material Affiliate Transaction that was not the subject of prior review by a committee of the Board of Directors with at least three members, each of whom is independent, and defines a Material Affiliate Transaction as a transaction or series of related transactions between Grupo Mexico or one of its affiliates (other than the Company or its subsidiaries), on the one hand, and the Company or one of its subsidiaries, on the other hand, that involves consideration of more than $10.0 million in the aggregate. It is the Company’s policy that (i) a Material Affiliate Transaction not be entered into or continued without the review and approval by the Audit Committee or its subcommittee of related party transactions comprised of independent directors,(ii) any potential related party transaction process with aggregate consideration between $8.0 million and $10.0 million be authorized by the General Counsel and Chief Financial Officer of the Company and (iii) that all related party transactions, including any Material Affiliate Transaction, be reported to the Audit Committee of the Board of Directors or to its subcommittee of related party transactions. ​ Receivable and payable balances with related parties are shown below (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ At September 30, ​ At December 31, ​ ​ 2021 2020 ​ Related parties receivable current: ​ ​ ​ ​ ​ ​ ​ Grupo Mexico and affiliates: ​ ​ ​ ​ ​ ​ ​ Asarco LLC ​ $ 7.8 ​ $ 5.3 ​ Compania Perforadora Mexico S.A.P.I. de C.V. and affiliates ​ 0.3 ​ 0.3 ​ Grupo Mexico ​ 2.7 ​ 2.7 ​ Grupo Mexico Servicios ​ ​ 0.1 ​ ​ — ​ Mexico Generadora de Energia S. de R.L. ("MGE") ​ ​ 23.3 ​ ​ 14.4 ​ Grupo Mexico Servicios de Ingenieria, S.A. de C.V. ​ ​ 0.2 ​ ​ 0.2 ​ Related to the controlling group: ​ ​ ​ ​ ​ ​ ​ Boutique Bowling de Mexico, S.A. de C.V. ​ ​ (*) ​ ​ 0.2 ​ Mexico Transportes Aereos, S.A. de C.V. ("Mextransport") ​ ​ 0.2 ​ ​ — ​ Operadora de Cinemas, S.A. de C.V. ​ ​ (*) ​ ​ 0.2 ​ ​ ​ $ 34.6 ​ $ 23.3 ​ ​ ​ ​ ​ ​ ​ ​ ​ Related parties payable: ​ ​ ​ ​ ​ ​ ​ Grupo Mexico and affiliates: ​ ​ ​ ​ ​ ​ ​ Asarco LLC ​ $ 20.4 ​ $ 13.9 ​ Eolica El Retiro, S.A.P.I. de C.V. ​ ​ 5.9 ​ ​ 0.3 ​ Ferrocarril Mexicano, S.A. de C.V. ​ 3.5 ​ 4.7 ​ Grupo Mexico ​ — ​ 0.9 ​ Grupo Mexico Servicios ​ 16.7 ​ 19.6 ​ Grupo Mexico Servicios de Ingenieria, S.A. de C.V. ​ ​ 0.8 ​ ​ 0.7 ​ MGE ​ ​ 50.6 ​ ​ 40.8 ​ Mexico Compania Constructora S.A de C.V. ​ ​ 14.1 ​ ​ 22.9 ​ Related to the controlling group: ​ ​ ​ ​ ​ ​ ​ Boutique Bowling de Mexico, S.A. de C.V. ​ 0.3 ​ 0.3 ​ Mexico Transportes Aereos, S.A. de C.V. (“Mextransport”) ​ 0.3 ​ 0.1 ​ Operadora de Cinemas, S.A. de C.V. ​ ​ 0.1 ​ ​ 0.1 ​ ​ ​ $ 112.7 ​ $ 104.3 ​ (*) Less than $0.1 million. Purchase and sale activity: ​ Grupo Mexico and affiliates: ​ The following table summarizes the purchase and sale activities with Grupo Mexico and its affiliates in the first nine months of 2021 and 2020 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ 2021 2020 Purchase activity ​ ​ ​ ​ ​ ​ Asarco LLC ​ $ 23.0 ​ $ 224.3 Eolica El Retiro, S.A.P.I. de C.V. ​ 6.2 ​ 0.8 Ferrocarril Mexicano, S.A. de C.V. ​ 33.1 ​ 36.8 Grupo Mexico ​ ​ — ​ ​ 7.5 Grupo Mexico Servicios ​ ​ 21.9 ​ ​ 13.4 Intermodal Mexico S.A. de C.V. ​ ​ 0.5 ​ ​ — MGE ​ 209.0 ​ 157.2 Mexico Proyectos y Desarrollos S.A. de C.V. and affiliates ​ ​ 43.8 ​ ​ 42.4 Peru Mining Exploration & Development Company ​ 0.4 ​ — Total purchases ​ $ 337.9 ​ $ 482.4 Sales activity ​ ​ ​ ​ ​ ​ Asarco LLC ​ $ 22.8 ​ $ 58.6 Grupo Mexico Servicios ​ ​ 0.1 ​ ​ 0.1 MGE ​ ​ 92.3 ​ ​ 37.7 Total sales ​ $ 115.2 ​ $ 96.4 ​ Grupo Mexico, the parent and the majority indirect stockholder of the Company, and its affiliates provide various services to the Company. These services are primarily related to accounting, legal, tax, financial, treasury, human resources, price risk assessment and hedging, purchasing, procurement and logistics, sales and administrative and other support services. The Company pays Grupo Mexico and Grupo Mexico Servicios, a subsidiary of Grupo Mexico, for these services and expects to continue requiring these services in the future. ​ In the first nine months of 2021, the Company made donations of $1.3 million to Fundacion Grupo Mexico, A.C., an organization dedicated to promoting the social and economic development of the communities close to the Company’s Mexican operations. In the same period of 2020, the Company made donations of $7.0 million to this organization. ​ The Company’s Mexican operations paid fees for freight services provided by Ferrocarril Mexicano, S.A de C.V. and for construction services provided by Intermodal Mexico, S.A. de C.V., which are all subsidiaries of Grupo Mexico. Additionally, the Company´s Peruvian and Mexican operations paid fees for engineering services provided by Grupo Mexico Servicios de Ingenieria, S.A. de C.V., and the Company’s Mexican operations paid fees for construction services provided by Mexico Compania Constructora S.A. de C.V. Both companies are subsidiaries of Mexico Proyectos y Desarrollos, S.A. de C.V., which is a subsidiary of Grupo Mexico. ​ In addition, the Company’s Peruvian operations purchased three mining concessions from Peru Mining Exploration & Development Company, a subsidiary of Grupo Mexico. ​ The Company’s Mexican operations purchased copper concentrates and rod from Asarco LLC and also paid fees for tolling services. Additionally, the Company´s Mexican operations purchased power from MGE. Both companies are subsidiaries of Grupo Mexico. ​ In 2012, the Company signed a power purchase agreement with MGE, whereby MGE will supply some of the Company’s Mexican operations with power through 2032. MGE has two natural gas-fired combined cycle power generating units, with a net total capacity of 516.2 megawatts and has been supplying power to the Company since December 2013. Currently, MGE is supplying 2.7% of its power output to third-party energy users, compared to 2.6% as of September 30, 2020. ​ In 2014, Mexico Generadora de Energia Eolica, S. de R.L. de C.V, an indirect subsidiary of Grupo Mexico, located in Oaxaca, Mexico, acquired Eolica el Retiro. Eolica el Retiro is a windfarm with 37 wind turbines. This company started operations in January 2014 and began to sell power to Industrial Minera Mexico, S.A. de C.V. and subsidiaries (IMMSA) and other subsidiaries of Grupo Mexico in the third quarter of 2014. Currently, Eolica el Retiro supplies 61.0% of its power output to IMMSA and Mexcobre, compared to 11.5% as of September 30, 2020. ​ The Company sold starter sheets, copper concentrate, sulfuric acid, silver and gold to Asarco LLC. In addition, the Company received rental fees from Grupo Mexico Servicios. ​ In September 2019, Asarco LLC signed a promissory agreement to pay to the Company´s Mexican operations $62.0 million plus interest no later than October 31, 2021, with quarterly payments of $0.5 million. The annual interest rate of the note was Libor plus 200 basis points, which would be reviewed annually. In November 2020, Asarco repaid this agreement. Related to this agreement, the Company recorded interest income of $1.8 million in the first nine months of 2020. ​ The Company also received fees for natural gas and services provided to MGE, a subsidiary of Grupo Mexico. In May 2020, MGE signed a promissory note to pay to the Company´s Mexican operations 97.2 million Mexican pesos (approximately $5.1 million) plus interest no later than November 30, 2020. The annual interest rate of the note was 8.28% with monthly payments. MGE repaid this note in December 2020. ​ Companies with relationships to the controlling group: ​ The following table summarizes the purchase and sales activities with other Larrea family companies in the first nine months of 2021 and 2020 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ 2021 2020 Purchase activity ​ ​ ​ ​ ​ ​ Boutique Bowling de Mexico S.A. de C.V. ​ $ 0.2 ​ $ 0.3 Mextransport ​ ​ 1.1 ​ ​ 3.0 Operadora de Cinemas S.A. de C.V. ​ ​ 0.1 ​ ​ 0.1 Total purchases ​ $ 1.4 ​ $ 3.4 ​ ​ ​ ​ ​ ​ ​ Sales activity ​ ​ ​ ​ ​ ​ Boutique Bowling de Mexico S.A. de C.V. ​ $ (*) ​ $ 0.1 Mextransport ​ ​ 1.4 ​ ​ 1.2 Operadora de Cinemas S.A. de C.V. ​ ​ (*) ​ ​ 0.1 Total sales ​ $ 1.4 ​ $ 1.4 (*) amount is lower than $0.1 million ​ The Larrea family controls a majority of the capital stock of Grupo Mexico and has extensive interests in other businesses, including transportation, real estate and entertainment. The Company engages in certain transactions in the ordinary course of business with other entities controlled by the Larrea family relating to the lease of office space, air transportation and entertainment. ​ The Company’s Mexican operations paid fees for entertainment services provided by Boutique Bowling de Mexico, S.A de C.V. and Operadora de Cinemas, S.A. de C.V. Both companies are controlled by the Larrea family. ​ Mextransport provides aviation services to the Company´s Mexican operations. This is a company controlled by the Larrea family. ​ In addition, the Company received fees for building rental and maintenance provided to Boutique Bowling de Mexico, S.A. de C.V. and Operadora de Cinemas, S.A. de C.V. The Company´s Mexican operations received fees from Mextransport for reimbursement of maintenance expenses and for rental services. ​ Equity Investment in Affiliate: ​ In addition, the Company has a 30.0% participation in Apu Coropuna S.R.L. (“Apu Coropuna”), which it accounts for on the equity method. Apu Coropuna is a company that performs exploration activities in the Pucay prospect, located in Arequipa, Peru. ​ It is anticipated that in the future the Company will enter into similar transactions with these same parties.

DERIVATIVE INSTRUMENTS_

DERIVATIVE INSTRUMENTS:	9 Months Ended
	Sep. 30, 2021
DERIVATIVE INSTRUMENTS:
DERIVATIVE INSTRUMENTS:	​ NOTE 6 — DERIVATIVE INSTRUMENTS: ​ From time to time, the Company uses derivative instruments to manage its cash flows exposure to changes in commodity prices. The Company does not enter into derivative contracts unless it anticipates that the possibility exists that future activity will expose the Company’s future cash flows to deterioration. Derivative contracts for commodities are entered into to manage the price risk associated with forecasted purchases of the commodities that the Company uses in its manufacturing process. ​ Cash Flow Hedges of Natural Gas ​ The Company’s objective in using natural gas derivatives is to protect the stability of natural gas costs and manage exposure to natural gas price increases. To protect natural gas costs from estimated price increases in the coming winter season, the Company acquired two derivative instruments that begin in November 2021 and end in March 2022. ​ Derivative instruments are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Call ​ Financial Swap ​ Derivatives designated as hedging instruments under ASC 815 ​ Option ​ Cash Settlement ​ ​ ​ ​ ​ ​ ​ ​ ​ Commodity contracts ​ ​ Natural gas ​ ​ Natural gas ​ Gas volume (MMBTUs) ​ ​ 5,285,000 ​ ​ 5,285,000 ​ Fixed price ($) ​ ​ 3.75 ​ ​ 0.55 ​ Total option premium (millions of $) ​ N/A ​ ​ 2.9 ​ Estimated fair value of assets (liabilities) as of September 30, 2021 (millions of $) ​ 12.1 ​ ​ (2.9) ​ Effect of derivative instruments on the consolidated Statement of Earnings (millions of $) ​ — ​ ​ — ​ (Favorable) unfavorable effect in OCI - net of deferred income taxes (millions of $) ​ ​ (8.4) ​ ​ 2.0 ​ ​ The Company assessed these derivative instruments as Cash Flow Hedges. As such, the effective portions of said hedges are initially reported in Other Comprehensive Income (OCI) and are reclassified as earnings in the same line item associated with the forecasted transaction and in the same period or periods during which the hedged transaction affects earnings. Any ineffective portions of these derivatives would be reported in earnings during the current period. ​ As of December 31, 2020, and September 30, 2020, the Company did not hold any derivative instruments.

LEASES_

LEASES:	9 Months Ended
	Sep. 30, 2021
LEASES:
LEASES:	​ NOTE 7 — LEASES: ​ The Company has operating leases for power generating facilities, vehicles and properties. The Company recognizes lease expense for these leases on a straight-line basis over the lease term. Some of the Company’s leases include both lease and non-lease components which are accounted for separately. The Company’s leases have remaining lease terms of one year to 11 years, and do not include options to extend the leases. The Company’s lease agreements do not contain options to purchase the leased assets or to terminate the leases before the expiration date. In addition, the Company’s lease contracts have no material residual value guarantees or material restrictive covenants. As none of the Company’s leases stipulates an implicit rate, the Company uses its incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. ​ The weighted average remaining lease term for the Company’s leases is eight years, and the weighted average discount rate for these leases is 3.74%. ​ The operating lease expense recognized in the first nine months of 2021 and 2020 was classified as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ Classification 2021 2020 Cost of sales (exclusive of depreciation, amortization and depletion) $ 85.8 ​ $ 86.4 Selling, general and administrative ​ 0.1 ​ 0.2 Exploration ​ 0.1 ​ 0.1 Total lease expense $ 86.0 ​ $ 86.7 ​ Maturities of lease liabilities are as follows: ​ ​ ​ ​ ​ ​ ​ Lease liabilities Year (in millions) 2021 $ 28.6 2022 ​ 113.7 2023 ​ 112.4 2024 ​ 104.7 2025 ​ 103.7 After 2025 ​ 723.0 Total lease payments $ 1,186.1 Less: interest on lease liabilities ​ (259.5) Present value of lease payments $ 926.6 ​

ASSET RETIREMENT OBLIGATION_

ASSET RETIREMENT OBLIGATION:	9 Months Ended
	Sep. 30, 2021
ASSET RETIREMENT OBLIGATION:
ASSET RETIREMENT OBLIGATION:	​ ​ NOTE 8 — ASSET RETIREMENT OBLIGATION: ​ Peruvian operations: ​ The Company maintains an asset retirement obligation for its mining properties in Peru, as required by the Peruvian Mine Closure Law. In accordance with the requirements of this law, the Company’s closure plans were approved by the Peruvian Ministry of Energy and Mines (“MINEM”). As part of the closure plans, the Company is required to provide annual guarantees over the estimated life of the mines, based on a present value approach, and to furnish the funds for the asset retirement obligation. This law requires a review of closing plans every five years . ​ On June 24, 2019, MINEM approved a change to the guarantees required for the mining closure plans. The new regulation specifies that annual guarantees can be secured with real estate up to a maximum of 50% of the total required and the remaining amount can be covered by credit instruments. Currently, the Company has pledged the value of its Lima office complex to back 50% of the guarantee and has a stand-by letter of credit for the other 50% as a security for this obligation.Through January 2021, the Company has provided total guarantees of $56.5 million. ​ The closure cost recognized for this liability includes the cost, as outlined in its closure plans, of dismantling the Toquepala and Cuajone concentrators, the Ilo smelter and refinery, and the shops and auxiliary facilities at the three units. In March 2016, MINEM approved the Mining Closure Plan for the Toquepala expansion project and the revised closure plans for the Cuajone mine and the Ilo facilities were approved in January and October 2019 respectively. Based on these new estimates, the Company increased the asset retirement obligation by $28.1 million in 2019. The closure plan for the Tia Maria project was approved in February 2017. However, the Company has not recorded a retirement obligation for the Tia Maria project because work on the project is still on hold. The Company believes that under these circumstances, the recording of a retirement obligation is not appropriate. ​ Mexican operations: ​ The Company has recognized an estimated asset retirement obligation for its mining properties in Mexico as part of its environmental commitment. Even though there is currently no enacted law, statute, ordinance, written or oral contract requiring the Company to carry out mine closure and environmental remediation activities, the Company believes that a constructive obligation presently exists based on the remediation requirements caused by the closure of any facility. The overall cost recognized for mining closure in Mexico includes the estimated costs of dismantling concentrators, smelter and refinery plants, shops and other facilities. ​ In 2020, the Company made a change in the estimate for the asset retirement obligation for its Mexican operations, mainly due to a detailed review of the closing activities required for each facility. The effect of this change was an increase in the asset retirement obligation of $269.3 million, which was recorded in December 2020. ​ The following table summarizes the asset retirement obligation activity for the first nine months of 2021 and 2020 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ 2021 2020 Balance as of January 1 ​ $ 545.0 ​ $ 262.3 Closure payments ​ (3.7) ​ (1.0) Accretion expense ​ 18.3 ​ 11.1 Balance as of September 30, ​ $ 559.6 ​ $ 272.4 ​

BENEFIT PLANS_

BENEFIT PLANS:	9 Months Ended
	Sep. 30, 2021
BENEFIT PLANS:
BENEFIT PLANS:	​ NOTE 9 — BENEFIT PLANS: ​ Post retirement defined benefit plans: ​ The Company has two non-contributory defined benefit pension plans to cover former salaried employees in the United States and certain former expatriate employees in Peru. Effective October 31, 2000, the Board of Directors amended the qualified pension plan to suspend the accrual of benefits. ​ In addition, the Company’s Mexican subsidiaries have a defined contribution pension plan for salaried employees and a non-contributory defined benefit pension plan for union employees. ​ The components of net periodic benefit costs for the first nine months of 2021 and 2020 are as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ (in millions) 2021 2020 Service cost ​ $ 1.1 ​ $ 1.0 Interest cost ​ 1.2 ​ 1.2 Expected return on plan assets ​ (2.6) ​ (2.1) Amortization of prior service cost / (credit) ​ 0.1 ​ 0.1 Amortization of net loss/(gain) ​ 0.2 ​ 0.2 Net periodic benefit cost ​ $ (0.0) ​ $ 0.4 ​ Post-retirement health care plans: ​ United States: The Company adopted a post-retirement health care plan for retired salaried employees eligible for Medicare in 1996. The Company manages the plan and is currently providing health benefits to retirees. The plan is accounted for in accordance with ASC 715 “Compensation retirement benefits”. ​ In Mexico, health services are provided by the Mexican Social Security Institute. ​ The components of net periodic benefit cost for the first nine months of 2021 and 2020 are as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ (in millions) 2021 2020 Interest cost ​ $ 1.3 ​ $ 0.9 Amortization of net loss (gain) ​ 0.1 ​ — Amortization of prior service cost/ (credit) ​ — ​ — Net periodic benefit cost ​ $ 1.4 ​ $ 0.9 ​

COMMITMENTS AND CONTINGENCIES_

COMMITMENTS AND CONTINGENCIES:	9 Months Ended
	Sep. 30, 2021
COMMITMENTS AND CONTINGENCIES:
COMMITMENTS AND CONTINGENCIES:	NOTE 10 — COMMITMENTS AND CONTINGENCIES: ​ Environmental matters: ​ The Company has instituted extensive environmental conservation programs at its mining facilities in Peru and Mexico. The Company’s environmental programs include, among others, water recovery systems to conserve water and minimize the impact on nearby streams, reforestation programs to stabilize the surface of the tailings dams and the implementation of scrubbing technology in the mines to reduce dust emissions. ​ Environmental capital investments in the first nine months of 2021 and 2020 were as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ 2021 2020 Peruvian operations (*) ​ $ 2.9 ​ $ (4.0) Mexican operations ​ 57.7 ​ 28.6 ​ ​ $ 60.6 ​ $ 24.6 (*) ​ Peruvian operations ​ Air Quality Standards (“AQS”): ​ Soil Environmental Quality Standards (“SQS”) ​ Climate change: Framework. This law establishes that promoting public and private investments in climate change management is of national interest. The law proposes creating an institutional framework to address climate change in Peru, and outlines new measures, particularly with respect to climate change mitigation. It includes, for example, provisions dealing with: increasing carbon capture and use of carbon sinks; afforestation and reforestation practices; land use changes; and sustainable systems of transportation, solid waste management, and energy systems. This is the first Latin American climate change framework law to incorporate obligations from the Paris Agreement. Regulations to this law were enacted by Supreme Decree 013-2019 published on December 31, 2019 and are applicable to all Peruvian institutions and agencies. It is expected that further Peruvian regulations will be applicable to non-governmental entities. The Company has initiated a multi-year process to align its reporting on climate change for its Peruvian operations with the recommendations of the Task Force on Climate-Related Financial Disclosures (TCFD). The Company is committed to the environment and to managing climate-related impacts. The Company’s focus is to seek continuous improvement in the responsible use of natural resources while complying with strict applicable legal standards for prevention, mitigation, control and remediation of environmental impacts. Implementing continuous improvement in the Company’s processes improves efficiency in the use and consumption of energy, water, and other natural resources. ​ Mexican operations ​ The principal legislation applicable to the Company’s Mexican operations is the Federal General Law of Ecological Balance and Environmental Protection (the “General Law”), which is enforced by the Federal Bureau of Environmental Protection (“PROFEPA”). PROFEPA monitors compliance with environmental legislation and enforces Mexican environmental laws, regulations and official standards. It may also initiate administrative proceedings against companies that violate environmental laws, which in the most extreme cases may result in the temporary or permanent shutdown of non-complying facilities, the revocation of operating licenses and/or other sanctions or fines. ​ In 2011, the General Law was amended to provide an individual or entity the ability to contest administrative acts, including environmental authorizations, permits or concessions granted, without the need to demonstrate the actual existence of harm to the environment as long as it can be argued that the harm may be caused. In addition, in 2011, amendments to the Civil Federal Procedures Code (“CFPC”) were enacted, which established three categories of collective actions under which a group of 30 or more individuals can be considered sufficient to prove a “legitimate interest” to file civil actions for injuries derived from alleged violations of environmental, consumer protection, financial services and economic competition laws and to seek restitution or economic compensation for the alleged injuries or the suspension of the activities which allegedly generated the injuries in question. The amendments to the CFPC may result in more litigation, with plaintiffs seeking remedies, including suspension of the activities alleged to cause harm. ​ In 2013, the Environmental Liability Federal Law was enacted. The law establishes general guidelines for actions to be considered likely to cause environmental harm. If a possible determination regarding harm occurs, environmental clean-up and remedial actions sufficient to restore environment to a pre-existing condition should be taken. Under this law, if restoration is not possible, compensation measures should be provided. Criminal penalties and monetary fines can be imposed under this law. ​ Guaymas sulfuric acid spill ​ On July 9, 2019, there was an incident at the Company´s Marine Terminal in Guaymas, Sonora, that caused the discharge of approximately three cubic meters of sulfuric acid into the sea in the industrial port area. ​ The Guaymas bay has an estimated water volume of 340 million cubic meters. The spill, upon entering in contact with the sea’s alkaline conditions, led to quick dilution of the discharge and the sulfuric acid was naturally and immediately neutralized. As a result, the discharge was considered harmless; the report from the Ministry of Navy found that neither the flora nor fauna of the port area were affected. On July 10, 2019, PROFEPA made a first inspection of the area, concluding that the Company executed all the appropiate procedures in order to contain the discharge, and no reference was made to the existence of negative impacts on the environment resulting from the incident. ​ On Friday, July 19, 2019, PROFEPA revisited the facilities to carry out a second inspection, declaring a partial temporary shutdown that affected only the storage process and transportation of sulfuric acid at the terminal, arguing the absence of an authorization of environmental impact. It is important to note that these facilities have been operating since 1979, prior to the 1988 Mexican General Law of Ecological Balance and the Protection of the Environment. Companies that were operating before the aforementioned law are exempt from the permit requirement. In addition, in 2009, PROFEPA awarded a certification of “Clean Industry and Environmental Quality” to the facility which was subsequently renewed four times (for a two-year period each time). ​ The Company filed a lawsuit against the closure, which was dismissed by a ruling on August 25, 2021. This ruling has been challenged through a motion to reopen the case, which was submitted on September 28, 2021. ​ The Company is not aware of the reasons or causes for this partial and temporary closure, but will continue working with the environmental authorities to provide certainty that the operation is in strict compliance with environmental regulations. The Company expects the environmental authorities to suspend the partial temporary shutdown, once they resolve their concerns. Currently, the Company does not expect any impact on its operations. As of September 30, 2021, the matter is pending resolution. ​ Climate change ​ Grupo Mexico, the indirect parent of SCC, has issued sustainability reports under the Global Reporting Initiative (GRI) for more than 10 years. Grupo Mexico also participates in different Mexican and international reporting programs such as the Greenhouse Gases (GHG) Mexico Program and the Carbon Disclosure Program (CDP). ​ In 2020, the Company began to align its disclosure of efforts to manage climate-related risks and opportunities with the recommendations of the TCFD (Task Force on Climate-Related Financial Disclosures). Grupo Mexico’s Sustainable Development Report 2020 included a section with specific details on the Company’s progress in this regard. This report includes information for all business divisions and subsidiaries, including information on the Company’s operations. ​ The Company believes that all of its facilities in Peru and Mexico are in material compliance with applicable environmental, mining and other applicable laws and regulations. The Company also believes that continued compliance with environmental laws of Mexico and Peru will have no material adverse effects on the Company’s business, properties, or operating results. ​ Litigation matters ​ Peruvian operations ​ The Tia Maria Mining Project ​ There are five lawsuits filed against the Peruvian Branch of the Company related to the Tia Maria project. The lawsuits seek (i) to declare null and void the resolution that approved the Environmental Impact Assessment of the project; (ii) the cancellation of the project and the withdrawal of mining activities in the area; (iii) to declare null and void the mining concession application for the Tia Maria project; and (iv) to declare null and void the resolution that approved the construction license. The lawsuits were filed by Messrs. Jorge Isaac del Carpio Lazo (filed May 22, 2015), Ernesto Mendoza Padilla (filed May 26, 2015), Juan Alberto Guillen Lopez (filed June 18, 2015), Junta de Usuarios del Valle del Tambo (filed April 30, 2015), and Gobierno Regional de Arequipa (filed December 16, 2019). ​ The del Carpio Lazio case was rejected by the court of first instance on November 14, 2016. The plaintiff filed an appeal before the Superior Court on January 3, 2017. On January 9, 2018, the lawyers of both parties presented their respective positions before the Appellate Court. On March 8, 2018, the Appellate Court issued its final decision, which upheld the first instance ruling. On April 27, 2018, the plaintiff filed an extraordinary appeal before the Supreme Court. As of September 30, 2021, the case remains pending resolution. ​ The Mendoza Padilla case was initially rejected by the lower court on July 8, 2015. This ruling was confirmed by the Superior Court on June 14, 2016. On July 12, 2016, the case was appealed before the Constitutional Court. On November 20, 2018, the Constitutional Court reversed the previous decisions and remanded the case to the lower court for further action. In the third quarter of 2020, the Company was notified that the complaint had been reinstated. The Company answered the complaint on September 15, 2020. On December 2, 2020, the lower court issued a resolution, considering the complaint answered. As of September 30, 2021, the case remains pending resolution. ​ The Guillen Lopez case is currently before the lower court. On July 19, 2019, the oral arguments took place. On January 7, 2020, the Judge decided to suspend the proceeding until the del Carpio Lazio case is concluded. Therefore, as of September 30, 2021, the case remains pending resolution. ​ The Junta de Usuarios del Valle del Tambo case is currently before the lower court. On May 2016, the Company was included in the process, after the Ministry of Energy and Mines filed a civil complaint. On March 6, 2019, the Company was formally notified of the lawsuit and answered the complaint on March 20, 2019. On July 8, 2019, the Company requested the suspension of the proceeding until the del Carpio Lazio case is concluded. As of September 30, 2021, the case remains pending resolution. ​ The Gobierno Regional de Arequipa case is currently before the lower court and the Company answered the complaint on September 15, 2020. As of September 30, 2021, the case remains pending resolution. ​ The Company asserts that these lawsuits are without merit and is vigorously defending against them. The potential contingency amount for these cases cannot be reasonably estimated by management at this time. ​ Special Regional Pasto Grande Project (“Pasto Grande Project”) ​ In 2012, the Pasto Grande Project, an entity of the Regional Government of Moquegua, filed a lawsuit against SCC’s Peruvian Branch alleging property rights over a certain area used by the Peruvian Branch and seeking the demolition of the tailings dam where SCC’s Peruvian Branch has deposited its tailings from the Toquepala and Cuajone operations since 1995. The Peruvian Branch has had title to use the area in question since 1960 and has, since 1995, constructed and operated the tailings dams with proper governmental authorization. Following a motion filed by the Peruvian Branch, the lower court has ​ Mexican operations ​ The Accidental Spill at Buenavista Mine of 2014 ​ In relation to the 2014 accidental spill of copper sulfate solution that occurred at a leaching pond in the Buenavista mine, the following legal procedures are pending against the Company: ​ On August 19, 2014, PROFEPA, as part of the administrative proceeding initiated after the spill, announced the filing of a criminal complaint against Buenavista del Cobre S.A. de C.V. (“BVC”), a subsidiary of the Company, in order to determine those responsible for environmental damages. During the second quarter of 2018, the criminal complaint was dismissed. This decision was appealed and was pending resolution as of September 30, 2021. ​ Through the first half of 2015, six collective action lawsuits were filed in federal courts in Mexico City and Sonora against two subsidiaries of the Company seeking economic compensation, clean up and remedial activities in order to restore the environment to its pre-existing conditions. Three of the collective action lawsuits have been dismissed by the court. As of September 30, 2021, three lawsuits were in process: two were filed by Acciones Colectivas de Sinaloa, A.C. and one by Defensa Colectiva, A.C., requesting precautionary measures about construction of facilities to monitor public health services and prohibiting the closure of the Rio Sonora Trust. ​ Similarly, in 2015, eight civil action lawsuits were filed against BVC in the state courts of Sonora seeking damages for alleged injuries and for moral damages as a consequence of the spill. The plaintiffs in the state court lawsuits are: Jose Vicente Arriola Nunez et al; Santana Ruiz Molina et al; Andres Nogales Romero et al; Teodoro Javier Robles et al; Gildardo Vasquez Carvajal et al; Rafael Noriega Souffle et al; Grupo Banamichi Unido de Sonora El Dorado, S.C. de R.L. de C.V; and Marcelino Mercado Cruz. In 2016, three additional civil action lawsuits, claiming similar damages, were filed by Juan Melquicedec Lebaron; Blanca Lidia Valenzuela Rivera et al and Ramona Franco Quijada et al. In 2017, BVC was served with thirty-three additional civil action lawsuits, claiming similar damages. The lawsuits were filed by Francisco Javier Molina Peralta et al; Anacleto Cohen Machini et al; Francisco Rafael Alvarez Ruiz et al; Jose Alberto Martinez Bracamonte et al; Gloria del Carmen Ramirez Duarte et al; Flor Margarita Sabori et al; Blanca Esthela Ruiz Toledo et al; Julio Alfonso Corral Domínguez et al; Maria Eduwiges Bracamonte Villa et al; Francisca Marquez Dominguez et al; Jose Juan Romo Bravo et al; Jose Alfredo Garcia Leyva et al; Gloria Irma Dominguez Perez et al; Maria del Refugio Romero et al; Miguel Rivas Medina et al; Yolanda Valenzuela Garrobo et al; Maria Elena Garcia Leyva et al; Manuel Alfonso Ortiz Valenzuela et al; Francisco Alberto Arvayo Romero et al; Maria del Carmen Villanueva Lopez et al; Manuel Martin Garcia Salazar; Miguel Garcia Arguelles et al; Dora Elena Rodriguez Ochoa et al; Honora Eduwiges Ortiz Rodriguez et al; Francisco Jose Martinez Lopez et al; Maria Eduwiges Lopez Bustamante; Rodolfo Barron Villa et al, Jose Carlos Martinez Fernandez et al, Maria de los Angeles Fabela et al; Rafaela Edith Haro et al; Luz Mercedes Cruz et al; Juan Pedro Montaño et al; and Juana Irma Alday Villa. During the first quarter of 2018, BVC was served with another civil action lawsuit, claiming similar damages. The lawsuit was filed by Alma Angelina Del Cid Rivera et al. In the last quarter of 2018, BVC was served with other three civil action lawsuits, claiming similar damages. These lawsuits were filed by Los Corrales de la Estancia, S.C. de R.L.; Jose Antonio Navarro; Jesus Maria Peña Molina, et al; these actions were dismissed by the court, because they have expired. As of September 30, 2021, forty-five cases were pending resolution. ​ In 2015, four constitutional lawsuits (juicios de amparo) were filed before Federal Courts against various authorities and against a subsidiary of the Company, arguing; (i) the alleged lack of a waste management program approved by SEMARNAT; (ii) the alleged lack of a remediation plan approved by SEMARNAT with regard to the August 2014 spill; (iii) the alleged lack of community approval regarding the environmental impact authorizations granted by SEMARNAT to one subsidiary of the Company; and (iv) the alleged inactivity of the authorities with regard to the spill in August 2014. The plaintiffs of these lawsuits are: Francisca Garcia Enriquez, et al filed two lawsuits, Francisco Ramon Miranda, et al and Jesus David Lopez Peralta et al. In the third quarter of 2016, four additional constitutional lawsuits, claiming similar damages were filed by Mario Alberto Salcido et al; Maria Elena Heredia Bustamante et al; Martin Eligio Ortiz Gamez et al; and Maria de los Angeles Enriquez Bacame et al. In the third quarter of 2017, BVC was served with another constitutional lawsuit filed by Francisca García Enriquez et al. In 2018, BVC was served with two additional constitutional lawsuits that were filed against SEMARNAT by Norberto Bustamante et al. Regarding the constitutional lawsuit filed by Maria Elena Heredia Bustamante et al; which claimed the lack of community approval for the authorization granted by SEMARNAT to build the new BVC tailings dam, on September 5, 2018, the Supreme Court of Justice issued a resolution establishing that such authorization was granted to BVC in compliance with the applicable legislation. However, SEMARNAT must hold a public meeting to inform the community of the technical aspects required to build the dam, potential impacts and prevention measures, with no material effects to Enriquez Bacame and Norberto Bustamante have been dismissed and closed without prejudice to the Company. As of September 30, 2021, the remaining cases were still pending resolution. ​ It is currently not possible to determine the extent of the damages sought in these state and federal lawsuits but the Company believes that these lawsuits are without merit. Accordingly, the Company is vigorously defending against them. Nevertheless, the Company believes that none of the legal proceedings resulting from the spill, individually or in the aggregate, would have a material effect on its financial position or results of operations. ​ Corporate operations ​ Carla Lacey, on behalf of herself and all other similarly situated stockholders of Southern Copper Corporation, and derivatively on behalf of Southern Copper Corporation ​ In April 2019, a derivative lawsuit was filed against the Company, certain current and former Directors, and Grupo Mexico in the Delaware Court of Chancery relating to certain construction contracts, contracts for the purchase and sale of minerals, and transportation contracts entered into between the Company’s subsidiaries and subsidiaries of Grupo Mexico. ​ In October 2019, the plaintiff amended the complaint to include claims related to certain administrative services contracts between the Company’s subsidiaries and Grupo Mexico. The amended complaint alleges, among other things, that the construction contracts, the mineral contracts, the transportation contracts, and the administrative services contracts were unfair as a result of breaches of fiduciary duties and the Company’s charter. The amended complaint also added Americas Mining Corporation (“AMC”) as a defendant, alleging that AMC breached its fiduciary duties as a controlling stockholder of the Company. The amended complaint seeks, among other things, unspecified monetary damages. In January 2020, the Company, the current and former Directors, and Grupo Mexico responded to the complaint by filing motions to dismiss. The Plaintiff filed a brief in response to the motions on March 13, 2020. On July 16, 2020, the Court denied the motions to dismiss the breach of fiduciary duty claims against the Directors. On October 6, 2020, the Court dismissed the Plaintiff’s claims against Grupo Mexico for lack of personal jurisdiction. On February 11, 2021, the Court granted the Directors’ motion to dismiss plaintiff’s breach of contract claim. The Court also granted AMC’s motion to dismiss all claims against AMC other than those related to the mineral contracts. ​ On July 12, 2021, the parties reached an agreement-in-principle to settle the lawsuit, subject to Court approval. On September 29, 2021, the parties filed a Stipulation and Agreement of Compromise, Settlement and Release with the Court. The Court has scheduled a hearing to consider the proposed settlement on February 1, 2022. ​ As of September 30, 2021, and until the Court has ruled on the proposed settlement, the Company is unable to determine whether an unfavorable outcome is either remote or probable. ​ Labor matters ​ Peruvian operations: ​ The Company decided to hold talks with the six unions to sign collective agreements prior to their effective dates. In June 2021, the Company signed a four-year collective agreement with one of the unions and granted, among other things, annual salary increases of 5% for each year from December 2021 and a signing bonus of S/ 60,000 (approximately $ 14,507 ​ On July 12, 2021, collective agreement extensions were signed with two other unions, under the same conditions as those indicated in the previous paragraph. ​ On July 22, 2021, a collective agreement with another union was extended for six years. This agreement granted, among other things, annual salary increases of 5% for each year from September 2021; a signing bonus of S/ 90,000 (approximately $ 21,760); and another long-term agreement bonus of S/ 10,000 (approximately $ 2,418), all of which which are being recorded as labor expense. ​ The Company continues to hold conversations in advance with the union whose agreement is in effect until August 31, 2022 for the purpose of extending the collective agreement. Finally, the last of the six unions, whose agreement expired in September 2021, decided to forego advancing conversations (in contrast with the decision taken by the other five unions). Currently, the Company is in the process of establishing a venue of formal negotiation with this union. The Company has decided, in accordance with the law, to end direct negotiations and enter into a conciliation phase with the participation of government labor authorities. ​ Mexican operations : ​ The workers of the San Martin mine began a strike in July 2007. On February 28, 2018, the striking workers of the San Martín mine of IMMSA held an election to vote on the union that would hold the collective bargaining agreement at the San Martín mine. The Federacion Nacional de Sindicatos Independientes (the National Federation of Independent Unions) won the vote by a majority. Nevertheless, the vote was challenged by the National Mining Union. On June 26, 2018, the Federal Mediation and Arbitration Board issued a ruling recognizing the election results. Due to the agreement between workers and the Company to end the protracted strike, on August 22, 2018, the Federal Mediation and Arbitration Board authorized the restart of operations of the San Martín mine. Such authorization was challenged by the National Mining Union. On April 4, 2019, the Federal Mediation and Arbitration Board recognized, once again, the election results from February 28, 2018, by which the National Federation of Independent Unions won by a majority. In the last quarter of 2019, a Federal Court issued a resolution that established that the Labor Court should analyze the list of workers with the right to vote in the union election. The Company and the National Federation of Independent Unions challenged such determination before the Supreme Court of Justice. Such challenges were dismissed by the Supreme Court. As a consequence, on September 6, 2021, the Federal Mediation and Arbitration Board issued a new resolution determining that, based on the documents submitted by the National Federation of Independent Unions and given the status of the strike until 2018, it was not possible to create a registry of workers holding a right to vote. Therefore, in case of a strike, any economic collective proceedings shall remain suspended. The Company expects that the conflict will be solved in accordance with the legal framework set by labor authorities and that any actions taken will respect the workers’ will. ​ As of September 30, 2021, the Company had completed most of the rehabilitation plan to restore operations at the San Martin mine, at a total expense of approximately $90.1 million; the mine has since reached full operating capacity. ​ In the case of the Taxco mine, its workers have been on strike since July 2007. After several legal procedures, in August 2015, the Supreme Court decided to assert jurisdiction over the case and to rule on it directly. As of September 30, 2021, the case was pending resolution without further developments. ​ It is expected that operations at the Taxco mine will remain suspended until the labor issues are resolved. In view of the lengthy strike, the Company has reviewed the carrying value of the Taxco mine to ascertain whether impairment exists. The Company concluded that there is a non-material impairment of the assets located at this mine. ​ In 2020, a small group of workers at the Charcas mine claimed an additional workers’ participation payment and a minor incident was reported. This claim lacked legal basis given that the Company had already completely fulfilled said obligation with the workers in question. Consequently, the Company took legal action and through conciliation and mediation with labor authorities, the incident concluded with no further repercussions for the Company. ​ Other legal matters ​ The Company is involved in various other legal proceedings incidental to its operations, but the Company does not believe that decisions adverse to it in any such proceedings, individually or in the aggregate, would have a material effect on its financial position or results of operations. ​ Other commitments: ​ Peruvian Operations ​ Tia Maria: ​ On August 1, 2014, the Company received final approval for Tia Maria´s Environmental Impact Assessment (“EIA”). On July 8, 2019, the Company received the construction permit for this 120,000 ton annual SX-EW copper greenfield project with a total capital budget of $1,400 million. This permit was obtained after completing an exhaustive review process, complying with all established regulatory requirements and addressing all observations raised. ​ On July 15, 2019, anti-mining groups staged a violent demonstration affecting economic as well as other activities in the Islay province. These actions were followed by the filing of three complaints, sponsored by groups opposing the Tia Maria project, with the Mining Council, which is the Peruvian administrative authority responsible for ruling on these complaints. The Mining Council temporarily suspended the construction permit on August 8, 2019. On October 7, 2019, as part of the process, the Mining Council conducted a hearing to hear the complaints and the Company´s position. On October 30, 2019, the Mining Council of the Peruvian Ministry of Energy and Mines ratified the construction permit for the Tia Maria project. ​ The Company has been working to promote the welfare of the Islay province population. As part of these efforts, the Company has implemented social programs in education, healthcare and productive development to improve the quality-of-life in the region. The Company also has promoted agricultural and livestock activities in the Tambo Valley and supported growth in manufacturing, fishing and tourism in Islay. ​ During the construction and operation phase, the Company will make it a priority to hire local labor to fill the 9,000 jobs (3,600 direct and 5,400 indirect) that the Company expects to generate during Tia Maria’s construction phase. When operating, the Company expects Tia Maria to directly employ 600 workers and indirectly provide jobs for another 4,200. Additionally, from day one of its operations, the Company will generate significant contributions to revenues in the Arequipa region via royalties and taxes. ​ Tia Maria´s project budget is approximately $1.4 billion, of which $340.7 million had been invested as of September 30, 2021. This project will use state-of-the-art SX-EW technology with the highest international environmental standards. SX-EW facilities are the most environmentally friendly in the industry as they do not require a smelting process and therefore, do not release any emissions into the atmosphere. ​ Michiquillay: ​ In June 2018, the Company signed a contract for the acquisition of the Michiquillay copper project in Cajamarca, Peru, at a purchase price of $400 million. Michiquillay is a world-class mining project with estimated mineralized material of 1,150 million tons and a copper grade of 0.63%. It is expected to produce 225,000 tons of copper per year (along with by-products of molybdenum, gold and silver) for an initial mine life of more than 25 years. ​ On September 3, 2021, the Company signed a social agreement with the Michiquillay community. The Company is also conducting talks to sign a similar agreement with the La Encañada community. Additionally, on October 1, 2021, the Peruvian Ministry of Energy and Mines approved the semi-detailed environmental impact study for the project. These events will allow the Company to initiate an in-depth exploration program in 2022. ​ The Company paid $12.5 million at the signing of the contract. In June 2021, the Company made an additional payment of $12.5 million. The balance of $375.0 million will be paid if the Company decides to develop the project, which is not a present obligation. ​ Corporate Social Responsibility: ​ The Company has a corporate social responsibility policy to maintain and promote the continuity of its mining operations and obtain the best results. The main objective of this policy is to integrate the Company´s operations with local communities in the areas of influence of its operations by creating permanent positive relationships to develop optimum social conditions and promote sustainable development in the area. Accordingly, the Company has made the following commitments: ​ Tacna Region: ​ As the Toquepala expansion project has been completed, the Company considers that these commitments constitute present obligations of the Company and consequently has recorded a liability of $32.5 million in its condensed consolidated financial statements as of September 30, 2021. ​ In addition, the Company has committed S/69.0 million (approximately $16.7 million) for the construction of a high-performance school in the Tacna region under the “social investment for taxes” (obras por impuestos) program, which allows the Company to use these amounts as an advance payment of taxes. ​ Moquegua Region: ​ In addition, the Company has committed S/86.7 million (approximately $21.0 million) to build two infrastructure projects in the Moquegua region under the “social investment for taxes” (obras por impuestos) program, which allows the Company to use these amounts as an advance payment of taxes. ​ Power purchase agreements: ​ ● Electroperu S.A.: In June 2014, the Company entered into a power purchase agreement for 120 megawatts (“MW”) with the state power company Electroperu S.A., under which Electroperu S.A. began supplying energy for the Peruvian operations for twenty years starting on April 17, 2017. ​ ● Kallpa Generacion S.A. (“Kallpa”): In July 2014, the Company entered into a power purchase agreement for 120MW with Kallpa, an independent Israeli owned power company, under which Kallpa will supply energy for the Peruvian operations for ten years starting on April 17, 2017 and ending on April 30, 2027. In May 2016, the Company signed an additional power purchase agreement for a maximum of 80MW with Kallpa, under which Kallpa began supplying energy for the Peruvian operations related to the Toquepala Expansion and other minor projects starting on May 1, 2017 and ending on October 31, 2029. ​ Mexican operations ​ Power purchase agreements: ​ ● MGE: In 2012, the Company signed a power purchase agreement with MGE, an indirect subsidiary of Grupo Mexico, to supply power to some of the Company’s Mexican operations through 2032. For further information, please see Note 5 “Related party transactions”. ​ ● Eolica el Retiro, S.A.P.I. de C.V.: In 201

STOCKHOLDERS' EQUITY_

STOCKHOLDERS' EQUITY:	9 Months Ended
	Sep. 30, 2021
STOCKHOLDERS' EQUITY:
STOCKHOLDERS' EQUITY:	​ NOTE 11 — STOCKHOLDERS’EQUITY: ​ Treasury Stock: ​ Activity in treasury stock in the nine-month period ended September 30, 2021 and 2020 is as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ 2021 2020 Southern Copper common shares ​ ​ ​ ​ ​ ​ Balance as of January 1, ​ $ 2,767.5 ​ $ 2,767.9 Used for corporate purposes ​ (0.1) ​ (0.4) Balance as of September 30, ​ 2,767.4 ​ 2,767.5 ​ ​ ​ ​ ​ ​ ​ Parent Company (Grupo Mexico) common shares ​ ​ ​ ​ ​ ​ Balance as of January 1, ​ 296.0 ​ 281.0 Other activity, including dividend, interest and foreign currency transaction effect ​ 17.4 ​ (0.5) Balance as of September 30, ​ 313.4 ​ 280.5 Treasury stock balance as of September 30, ​ $ 3,080.8 ​ $ 3,048.0 ​ ​ Southern Copper Common Shares: ​ At September 30, 2021 and at December 31, 2020, there were in treasury 111,514,817 and 111,522,817 shares of SCC’s common stock, respectively. SCC share repurchase program: ​ In 2008, the Company’s Board of Directors (“BOD”) authorized a $500 million share repurchase program that has since been increased by the BOD and is currently authorized to $3 billion. Pursuant to this program, the Company has purchased 119.5 million shares of common stock at a cost of $2.9 billion. These shares are available for general corporate purposes. The Company may purchase additional shares of its common stock from time to time, based on market conditions and other factors. This repurchase program has no expiration date and may be modified or discontinued at any time. ​ The NYSE closing price for SCC common shares as of September 30, 2021 was $56.14 and the maximum number of shares that the Company could purchase at that price was 1.5 million. ​ As a result of the repurchase of shares of SCC’s common stock, Grupo Mexico’s direct and indirect ownership was 88.9% as of September 30, 2021. There has been no activity in the SCC share repurchase program since the third quarter of 2016. ​ Directors’ Stock Award Plan: ​ The Company established a stock award compensation plan for certain directors who are not compensated as employees of the Company. Under this plan, participants currently receive 1,600 shares of common stock upon election and 1,600 additional shares following each annual meeting of stockholders thereafter. 600,000 shares of Southern Copper common stock have been reserved for this plan. On April 26, 2018, the Company's stockholders approved a five-year extension of the Plan until January 29, 2023 and an increase of the shares award from 1,200 to 1,600. The fair value of the award is measured each year at the date of the grant. Commencing with the 2021 grant, the 1,600 shares shall be granted quarterly and conditioned upon the attendance of each director to each Board meeting. The award is not subject to vesting requirements. ​ Parent Company common shares: ​ At September 30, 2021 and at December 31, 2020 there were in treasury 85,841,694 and 87,598,097 of Grupo Mexico’s common shares, respectively. ​ Employee Stock Purchase Plan: ​ 2015 Plan 10 ​ If Grupo Mexico pays dividends on shares during the eight year period, the participants will be entitled to receive the dividend in cash for all shares that have been fully purchased and paid as of the date that the dividend is paid. If the participant has only partially paid for shares, the entitled dividends will be used to reduce the remaining liability owed for purchased shares. ​ In the case of voluntary or involuntary resignation/termination of the employee, the Company will pay to the employee the fair market sales price at the date of resignation of the fully paid shares, net of costs and taxes. When the fair market sales value of the shares is higher than the purchase price, the Company will apply a deduction over the amount to be paid to the employee based on a decreasing schedule specified in the plan. ​ In case of retirement or death of the employee, the Company will render the buyer or his legal beneficiary, the fair market sales value as of the date of retirement or death of the shares effectively paid, net of costs and taxes. ​ The stock based compensation expense for the first nine months of 2021 and 2020 and the unrecognized compensation expense under this plan were as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ 2021 2020 Stock based compensation expense ​ $ 0.5 ​ $ 0.5 Unrecognized compensation expense ​ $ 1.0 ​ $ 1.5 ​ The following table presents the activity of this plan for the nine months ended September 30, 2021 and 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ Unit Weighted Average ​ ​ Shares ​ Grant Date Fair Value Outstanding shares at January 1, 2021 1,264,410 ​ $ 2.63 Granted — ​ — Exercised (381,288) ​ $ 2.63 Forfeited — ​ — Outstanding shares at September 30, 2021 883,122 ​ $ 2.63 Outstanding shares at January 1, 2020 1,379,734 ​ $ 2.63 Granted — ​ — Exercised (54,221) ​ $ 2.63 Forfeited — ​ — Outstanding shares at September 30, 2020 1,325,513 ​ $ 2.63 ​ 2018 Plan: 10 ​ If Grupo Mexico pays dividends on shares during the eight-year period, the participants will be entitled to receive the dividend in cash for all shares that have been fully purchased and paid as of the date that the dividend is paid. If the participant has only partially paid for shares, the entitled dividends will be used to reduce the remaining liability owed for purchased shares. ​ In the case of voluntary or involuntary resignation/termination of the employee, the Company will pay to the employee the fair market sales price on the date of resignation of the fully paid shares, net of costs and taxes. When the fair market sales value of the shares is higher than the purchase price, the Company will apply a deduction over the amount to be paid to the employee based on a decreasing schedule specified in the plan. ​ In case of retirement or death of the employee, the Company will render the buyer or his legal beneficiary, the fair market sales value as of the date of retirement or death of the shares effectively paid, net of costs and taxes. ​ The stock based compensation expense for the nine months ended September 30, 2021 and 2020 and the unrecognized compensation expense under this plan were as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ 2021 ​ 2020 Stock based compensation expense ​ $ 0.5 $ 0.5 Unrecognized compensation expense ​ $ 3.3 $ 4.0 ​ ​ The following table presents the stock award activity of this plan for the nine months ended September 30, 2021 and 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unit Weighted Average ​ Shares Grant Date Fair Value Outstanding shares at January 1, 2021 3,918,458 $ 1.86 Granted — ​ — Exercised (716,449) $ 1.86 Forfeited — ​ — Outstanding shares at September 30, 2021 3,202,009 $ 1.86 Outstanding shares at January 1, 2020 ​ 4,002,898 $ 1.86 Granted ​ — ​ — Exercised ​ (37,940) $ 1.86 Forfeited ​ — ​ — Outstanding shares at September 30, 2020 3,964,958 $ 1.86 ​ Non-controlling interest: ​ The following table presents the non-controlling interest activity for the nine months ended September 30, 2021 and 2020 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ 2021 2020 Balance as of January 1, $ 51.2 $ 47.9 Net earnings ​ 10.6 ​ 4.9 Dividend paid ​ (4.4) ​ (2.8) Balance as of September 30, $ 57.4 $ 50.0 ​

FAIR VALUE MEASUREMENT_

FAIR VALUE MEASUREMENT:	9 Months Ended
	Sep. 30, 2021
FAIR VALUE MEASUREMENT:
FAIR VALUE MEASUREMENT:	​ NOTE 12 — FAIR VALUE MEASUREMENT: ​ Subtopic 820-10 of ASC “Fair value measurement and disclosures — Overall” establishes a fair value 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 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). The three levels of the fair value hierarchy under Subtopic 820-10 are described below: ​ Level 1 - Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities. ​ Level 2 - Inputs that are observable, either directly or indirectly, but do not qualify as Level 1 inputs. (i.e., quoted prices for similar assets or liabilities). ​ Level 3 - Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (i.e., supported by little or no market activity). ​ The carrying amounts of certain financial instruments, including cash and cash equivalents, accounts receivable (other than accounts receivable associated with provisionally priced sales) and accounts payable approximate fair value due to their short maturities. Consequently, such financial instruments are not included in the following table, which provides information about the carrying amounts and estimated fair values of other financial instruments that are not measured at fair value in the condensed consolidated balance sheet as of September 30, 2021 and December 31, 2020 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ At September 30, 2021 ​ At December 31, 2020 ​ Carrying Value Fair Value Carrying Value Fair Value Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Long-term debt level 1 ​ ​ 6,195.8 ​ ​ 8,124.6 ​ ​ 6,193.6 ​ ​ 8,692.1 Long-term debt level 2 ​ ​ 350.9 ​ ​ 378.4 ​ ​ 350.6 ​ ​ 385.7 Total long-term debt ​ $ 6,546.7 ​ $ 8,503.0 ​ $ 6,544.2 ​ $ 9,077.8 ​ Long-term debt is carried at amortized cost and its estimated fair value is based on quoted market prices classified as Level 1 in the fair value hierarchy except for the cases of the Yankee bonds and the notes due 2022, which qualify as Level 2 in the fair value hierarchy as they are based on quoted prices in markets that are not active. ​ Fair values of assets and liabilities measured at fair value on a recurring basis were calculated as follows as of September 30, 2021 and December 31, 2020 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value at Measurement Date Using: ​ ​ ​ ​ ​ Significant ​ ​ ​ ​ Fair Value ​ Quoted prices in ​ other ​ Significant ​ ​ as of ​ active markets for ​ observable ​ unobservable ​ ​ September 30, ​ identical assets ​ inputs ​ inputs Description ​ 2021 ​ (Level 1) ​ (Level 2) ​ (Level 3) Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Short term investment: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — ​ $ 626.4 ​ $ 626.4 ​ $ — ​ $ — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate bonds ​ — ​ ​ — ​ ​ — ​ ​ — Asset backed securities ​ 0.2 ​ ​ — ​ ​ 0.2 ​ ​ — Mortgage backed securities ​ 0.2 ​ ​ — ​ ​ 0.2 ​ ​ — Accounts receivable: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Provisionally priced sales: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Copper ​ 707.1 ​ 707.1 ​ ​ — ​ ​ — Molybdenum ​ 281.7 ​ 281.7 ​ — ​ ​ — Total ​ $ 1,615.6 ​ $ 1,615.2 ​ $ 0.4 ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value at Measurement Date Using: ​ ​ ​ ​ ​ Significant ​ ​ ​ ​ Fair Value ​ Quoted prices in ​ other ​ Significant ​ ​ as of ​ active markets for ​ observable ​ unobservable ​ ​ December 31, ​ identical assets ​ inputs ​ inputs Description ​ 2020 ​ (Level 1) ​ (Level 2) ​ (Level 3) Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Short term investment: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — ​ $ 410.2 ​ $ 410.2 ​ $ — ​ $ — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate bonds ​ — ​ ​ — ​ ​ — ​ ​ — Asset backed securities ​ 0.3 ​ ​ — ​ 0.3 ​ ​ — Mortgage backed securities ​ 0.3 ​ ​ — ​ ​ 0.3 ​ ​ — Accounts receivable: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Provisionally priced sales: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Copper ​ 491.9 ​ 491.9 ​ ​ — ​ ​ — Molybdenum ​ 129.2 ​ 129.2 ​ — ​ ​ — Total ​ $ 1,031.9 ​ $ 1,031.3 ​ $ 0.6 ​ $ — ​ The Company’s short-term trading securities investments are classified as Level 1 because they are valued using quoted prices of the same securities as they consist of bonds issued by public companies and are publicly traded. The Company’s short-term available-for-sale investments are classified as Level 2 because they are valued using quoted prices for similar investments. ​ The Company’s accounts receivables associated with provisionally priced copper sales are valued using quoted market prices based on the forward price on the LME or on the COMEX. Such value is classified within Level 1 of the fair value hierarchy. Molybdenum prices are established by reference to the publication Platts Metals Week and are considered Level 1 in the fair value hierarchy. ​ In addition, in the third quarter of 2021 the Company acquired two derivative instruments to protect natural gas costs from estimated price increases in the coming winter season. These derivative instruments will cover the period from November 2021 through March 2022. For further information please refer to Note 6 “Derivative instruments.”

REVENUE_

REVENUE:	9 Months Ended
	Sep. 30, 2021
REVENUE:
REVENUE:	​ NOTE 13 — REVENUE: ​ The Company’s net sales were $8,110.4 million in the nine months ended September 30, 2021, compared to $5,634.2 million in the same period of 2020. The geographic breakdown of the Company’s sales is as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2021 ​ ​ ​ ​ Mexican ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mexican ​ IMMSA ​ Peruvian ​ Corporate & ​ ​ ​ ​ Open-Pit Unit Operations Elimination Consolidated The Americas: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mexico ​ $ 483.1 ​ $ 115.7 ​ $ 4.5 ​ $ (42.8) ​ $ 560.5 United States ​ 324.9 ​ 11.2 ​ 71.3 ​ — ​ 407.4 Peru ​ — ​ (0.4) ​ 148.3 ​ — ​ 147.9 Brazil ​ — ​ 10.9 ​ 93.2 ​ — ​ 104.1 Chile ​ (0.1) ​ — ​ 113.8 ​ — ​ 113.7 Other American countries ​ 10.9 ​ — ​ 1.8 ​ — ​ 12.7 Europe: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Switzerland ​ 276.0 ​ 20.3 ​ 127.6 ​ — ​ 423.9 Italy ​ — ​ 3.9 ​ 62.9 ​ — ​ 66.8 Spain ​ 106.6 ​ — ​ 20.4 ​ — ​ 127.0 Other European countries ​ 54.2 ​ 7.0 ​ 110.9 ​ — ​ 172.1 Asia: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Singapore ​ 119.9 ​ 6.3 ​ 159.7 ​ — ​ 285.9 Japan ​ (0.8) ​ — ​ 167.7 ​ — ​ 166.9 Other Asian countries ​ 51.1 ​ 0.2 ​ 40.7 ​ — ​ 92.0 Total ​ $ 1,425.8 ​ $ 175.1 ​ $ 1,122.8 ​ $ (42.8) ​ $ 2,680.9 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2021 ​ ​ ​ ​ Mexican ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mexican ​ IMMSA ​ Peruvian ​ Corporate & ​ ​ ​ ​ Open-Pit Unit Operations Elimination Consolidated The Americas: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mexico ​ $ 1,431.7 ​ $ 291.8 ​ $ 4.5 ​ $ (107.9) ​ $ 1,620.1 United States ​ 1,107.5 ​ 42.9 ​ 152.2 ​ — ​ 1,302.6 Peru ​ — ​ (0.3) ​ 438.9 ​ — ​ 438.6 Brazil ​ — ​ 18.4 ​ 310.8 ​ — ​ 329.2 Chile ​ 2.8 ​ — ​ 265.1 ​ — ​ 267.9 Other American countries ​ 28.9 ​ 0.7 ​ 4.6 ​ — ​ 34.2 Europe: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Switzerland ​ 888.7 ​ 46.0 ​ 323.1 ​ — ​ 1,257.8 Italy ​ 0.2 ​ 5.9 ​ 244.8 ​ — ​ 250.9 Spain ​ 299.8 ​ — ​ 63.8 ​ — ​ 363.6 Other European countries ​ 202.2 ​ 40.3 ​ 310.8 ​ — ​ 553.3 Asia: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Singapore ​ 354.8 ​ 14.8 ​ 395.7 ​ — ​ 765.3 Japan ​ 23.6 ​ — ​ 478.1 ​ — ​ 501.7 Other Asian countries ​ 196.4 ​ 0.3 ​ 228.5 ​ — ​ 425.2 Total ​ $ 4,536.6 ​ $ 460.8 ​ $ 3,220.9 ​ $ (107.9) ​ $ 8,110.4 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2020 ​ ​ ​ ​ ​ Mexican ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mexican ​ IMMSA ​ Peruvian ​ Corporate & ​ ​ ​ ​ Open-Pit Unit Operations Elimination Consolidated The Americas: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mexico ​ $ 319.5 ​ $ 84.5 ​ $ — ​ $ (29.7) ​ $ 374.3 United States ​ 309.9 ​ 11.3 ​ 33.6 ​ — ​ ​ 354.8 Peru ​ — ​ 4.8 ​ 95.1 ​ — ​ ​ 99.9 Brazil ​ — ​ 6.7 ​ 58.9 ​ — ​ ​ 65.6 Chile ​ — ​ — ​ 55.4 ​ — ​ ​ 55.4 Other American countries ​ 16.9 ​ 0.7 ​ 1.0 ​ — ​ ​ 18.6 Europe: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Switzerland ​ ​ 274.0 ​ 19.2 ​ 153.4 ​ — ​ ​ 446.6 Italy ​ ​ — ​ 2.0 ​ 60.2 ​ — ​ ​ 62.2 Spain ​ ​ 62.5 ​ — ​ — ​ — ​ ​ 62.5 Other European countries ​ ​ 42.4 ​ 11.0 ​ 83.2 ​ — ​ ​ 136.6 Asia: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Singapore ​ ​ 55.9 ​ 0.6 ​ 136.2 ​ — ​ ​ 192.7 Japan ​ ​ 15.2 ​ — ​ 129.1 ​ — ​ ​ 144.3 Other Asian countries ​ ​ 85.4 ​ 0.1 ​ 30.1 ​ — ​ ​ 115.6 Total ​ $ 1,181.7 ​ $ 140.9 ​ $ 836.2 ​ $ (29.7) ​ $ 2,129.1 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2020 ​ ​ ​ ​ ​ Mexican ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mexican ​ IMMSA ​ Peruvian ​ Corporate & ​ ​ ​ ​ Open-Pit Unit Operations Elimination Consolidated The Americas: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mexico ​ $ 890.3 ​ $ 254.2 ​ $ — ​ $ (78.0) ​ $ 1,066.5 United States ​ 866.8 ​ 15.5 ​ 94.0 ​ — ​ ​ 976.3 Peru ​ — ​ 10.4 ​ 208.2 ​ — ​ ​ 218.6 Brazil ​ — ​ 11.6 ​ 134.3 ​ — ​ ​ 145.9 Chile ​ 19.5 ​ — ​ 144.7 ​ — ​ ​ 164.2 Other American countries ​ 25.9 ​ 2.1 ​ 1.4 ​ — ​ ​ 29.4 Europe: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Switzerland ​ ​ 682.6 ​ 50.1 ​ 367.7 ​ — ​ ​ 1,100.4 Italy ​ ​ — ​ 6.3 ​ 179.1 ​ — ​ ​ 185.4 Spain ​ ​ 127.3 ​ — ​ — ​ — ​ ​ 127.3 Other European countries ​ ​ 118.8 ​ 20.7 ​ 203.1 ​ — ​ ​ 342.6 Asia: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Singapore ​ ​ 233.9 ​ 5.7 ​ 383.0 ​ — ​ ​ 622.6 Japan ​ ​ 26.9 ​ — ​ 365.9 ​ — ​ ​ 392.8 Other Asian countries ​ ​ 160.1 ​ 0.4 ​ 101.7 ​ — ​ ​ 262.2 Total ​ $ 3,152.1 ​ $ 377.0 ​ $ 2,183.1 ​ $ (78.0) ​ $ 5,634.2 ​ The following table presents information regarding the sales value by reporting segment of the Company’s significant products for the three and nine months ended September 30, 2021 and 2020 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2021 ​ ​ ​ Mexican ​ ​ ​ ​ ​ ​ ​ ​ Mexican IMMSA Peruvian Corporate, Other & Total ​ ​ Open-pit ​ Unit ​ Operations ​ Eliminations ​ Consolidated Copper ​ $ 1,195.0 ​ $ 24.3 ​ $ 912.9 ​ $ (21.8) ​ $ 2,110.4 Molybdenum ​ 146.6 ​ — ​ 147.9 ​ — ​ 294.5 Silver ​ 52.4 ​ 37.2 ​ 33.6 ​ (19.0) ​ 104.2 Zinc ​ — ​ 98.6 ​ — ​ 0.1 ​ 98.7 Other ​ 31.8 ​ 15.0 ​ 28.4 ​ (2.1) ​ 73.1 Total ​ $ 1,425.8 ​ $ 175.1 ​ $ 1,122.8 ​ $ (42.8) ​ $ 2,680.9 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2021 ​ ​ ​ Mexican ​ ​ ​ ​ ​ ​ ​ ​ Mexican IMMSA Peruvian Corporate, Other & Total ​ ​ Open-pit ​ Unit ​ Operations ​ Eliminations ​ Consolidated Copper ​ $ 3,858.2 ​ $ 75.5 ​ $ 2,697.1 ​ $ (54.7) ​ $ 6,576.1 Molybdenum ​ 387.3 ​ — ​ 359.0 ​ — ​ 746.3 Silver ​ 193.1 ​ 122.6 ​ 95.8 ​ ​ (48.1) ​ 363.4 Zinc ​ — ​ 215.1 ​ — ​ 0.5 ​ 215.6 Other ​ 98.0 ​ 47.6 ​ 69.0 ​ (5.6) ​ 209.0 Total ​ $ 4,536.6 ​ $ 460.8 ​ $ 3,220.9 ​ $ (107.9) ​ $ 8,110.4 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2020 ​ ​ ​ Mexican ​ ​ ​ ​ ​ ​ ​ ​ Mexican IMMSA Peruvian Corporate, Other & Total ​ ​ Open-pit ​ Unit ​ Operations ​ Eliminations ​ Consolidated Copper ​ $ 1,022.1 ​ $ 21.2 ​ $ 720.7 ​ $ (14.1) ​ $ 1,749.9 Molybdenum ​ 58.2 ​ — ​ 61.6 ​ — ​ 119.8 Silver ​ 67.0 ​ 48.4 ​ 35.1 ​ (17.5) ​ 133.0 Zinc ​ — ​ 57.6 ​ — ​ 4.6 ​ 62.2 Other ​ 34.4 ​ 13.7 ​ 18.8 ​ (2.7) ​ 64.2 Total ​ $ 1,181.7 ​ $ 140.9 ​ $ 836.2 ​ $ (29.7) ​ $ 2,129.1 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2020 ​ ​ ​ Mexican ​ ​ ​ ​ ​ ​ ​ ​ Mexican IMMSA Peruvian Corporate, Other & Total ​ ​ Open-pit ​ Unit ​ Operations ​ Eliminations ​ Consolidated Copper ​ $ 2,687.8 ​ $ 50.9 ​ $ 1,881.4 ​ $ (34.7) ​ $ 4,585.4 Molybdenum ​ 188.3 ​ — ​ 164.5 ​ — ​ 352.8 Silver ​ 170.6 ​ 111.1 ​ 77.6 ​ ​ (38.9) ​ 320.4 Zinc ​ — ​ 174.1 ​ — ​ 1.3 ​ 175.4 Other ​ 105.4 ​ 40.9 ​ 59.6 ​ (5.7) ​ 200.2 Total ​ $ 3,152.1 ​ $ 377.0 ​ $ 2,183.1 ​ $ (78.0) ​ $ 5,634.2 ​ ​ The opening and closing balances of receivables by reporting segment of the Company were as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mexican ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mexican IMMSA Peruvian Corporate & ​ ​ ​ ​ Open-Pit ​ Unit ​ Operations ​ Elimination ​ Consolidated ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of September 30, 2021: ​ ​ ​ ​ ​ Trade receivables ​ $ 658.8 ​ $ 57.1 ​ $ 777.5 ​ $ — ​ $ 1,493.4 Related parties, current ​ 25.1 ​ — ​ 1.7 ​ 7.8 ​ 34.6 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2020: ​ ​ ​ ​ ​ Trade receivables ​ $ 566.0 ​ $ 57.8 ​ $ 445.1 ​ $ — ​ $ 1,068.9 Related parties, current ​ 15.4 ​ — ​ 0.8 ​ 7.1 ​ 23.3 ​ As of September 30, 2021, the Company has long-term contracts with promises to deliver the following products in 2021: ​ ​ ​ ​ Copper concentrates (in tons) 188,000 Copper cathodes (in tons) ​ 48,000 Molybdenum concentrates (in tons) 41,414 Sulfuric acid (in tons) 322,415 ​ Provisionally priced sales ​ Following are the provisionally priced copper and molybdenum sales outstanding at September 30, 2021: ​ ​ ​ ​ ​ ​ ​ ​ ​ Sales volume Priced at ​ ​ ​ (million lbs.) ​ (per pound) ​ Month of settlement Copper ​ 174.1 ​ 4.06 ​ October 2021 through February 2022 Molybdenum ​ 15.3 ​ 18.45 ​ October 2021 through December 2021 ​ The provisional sales price adjustment included in accounts receivable and net sales as of September 30, 2021 includes negative adjustments of $30.7 ​ Management believes that the final pricing of these sales will not have a material effect on the Company’s financial position or on operating results.

SEGMENT AND RELATED INFORMATION

SEGMENT AND RELATED INFORMATION:	9 Months Ended
	Sep. 30, 2021
SEGMENT AND RELATED INFORMATION:
SEGMENT AND RELATED INFORMATION:	​ NOTE 14 — SEGMENT AND RELATED INFORMATION: ​ Company management views Southern Copper as having three reportable segments and manages it on the basis of these segments. The reportable segments identified by the Company are: the Peruvian operations, the Mexican open-pit operations and the Mexican underground mining operations segment identified as the IMMSA unit. ​ The three reportable segments identified are groups of mines, each of which constitute an operating segment, with similar economic characteristics, types of products, processes and support facilities, similar regulatory environments, similar employee bargaining contracts and similar currency risks. In addition, each mine within the individual group earns revenues from similar types of customers for their products and services and each group incurs expenses independently, including commercial transactions between groups. ​ Financial information is regularly prepared for each of the three segments and the results of the Company’s operations are regularly reported to the Chief Operating Decision Maker (“CODM”) on the segment basis. The CODM of the Company focuses on operating income and on total assets as measures of performance to evaluate different segments and to make decisions to allocate resources to the reported segments. These are common measures in the mining industry. ​ Financial information relating to Southern Copper’s segments is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2021 ​ ​ (in millions) ​ ​ Mexican ​ ​ Corporate, other ​ ​ ​ ​ Mexican ​ IMMSA ​ Peruvian ​ and ​ ​ ​ ​ ​ Open-pit ​ Unit ​ Operations ​ eliminations ​ Consolidated Net sales outside of segments ​ $ 1,425.8 ​ $ 132.3 ​ $ 1,122.8 ​ $ — ​ $ 2,680.9 Intersegment sales ​ — ​ ​ 42.8 ​ — ​ (42.8) ​ — Cost of sales (exclusive of depreciation, amortization and depletion) ​ 433.4 ​ 135.8 ​ 406.7 ​ (48.4) ​ 927.5 Selling, general and administrative ​ 17.4 ​ 2.9 ​ 8.1 ​ 2.9 ​ 31.3 Depreciation, amortization and depletion ​ 97.8 ​ 12.7 ​ 83.5 ​ 9.4 ​ 203.4 Exploration ​ 0.6 ​ 1.7 ​ 2.7 ​ 5.9 ​ 10.9 Operating income ​ $ 876.6 ​ $ 22.0 ​ $ 621.8 ​ $ (12.6) ​ ​ 1,507.8 Less: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest, net ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (87.4) Other income (expense) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1.9) Income taxes ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (548.6) Equity earnings of affiliate ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1.3 Non-controlling interest ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (3.6) Net income attributable to SCC ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 867.6 Capital investment ​ $ 114.6 ​ $ 29.0 ​ $ 97.2 ​ $ 2.3 ​ $ 243.1 Property and mine development, net ​ $ 4,551.1 ​ $ 555.5 ​ $ 3,713.0 ​ $ 656.5 ​ $ 9,476.1 Total assets ​ $ 8,200.6 ​ $ 1,009.9 ​ $ 4,774.2 ​ $ 4,125.6 ​ $ 18,110.3 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2021 ​ ​ (in millions) ​ ​ Mexican ​ ​ Corporate, other ​ ​ ​ ​ Mexican ​ IMMSA ​ Peruvian ​ and ​ ​ ​ ​ ​ Open-pit ​ Unit ​ Operations ​ eliminations ​ Consolidated Net sales outside of segments ​ $ 4,536.6 ​ $ 352.9 ​ $ 3,220.9 ​ $ — ​ $ 8,110.4 Intersegment sales ​ — ​ 107.9 ​ — ​ (107.9) ​ — Cost of sales (exclusive of depreciation, amortization and depletion) ​ 1,441.6 ​ 328.8 ​ 1,208.9 ​ (122.5) ​ 2,856.8 Selling, general and administrative ​ 49.7 ​ 7.8 ​ 27.0 ​ 8.4 ​ 92.9 Depreciation, amortization and depletion ​ 289.0 ​ 39.4 ​ 242.6 ​ 28.4 ​ 599.4 Exploration ​ 1.8 ​ 3.8 ​ 9.9 ​ 11.2 ​ 26.7 Operating income ​ $ 2,754.5 ​ $ 81.0 ​ $ 1,732.5 ​ $ (33.4) ​ ​ 4,534.6 Less: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest, net ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (262.6) Other income (expense) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (7.8) Income taxes ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1,703.8) Equity earnings of affiliate ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 14.4 Non-controlling interest ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (10.6) Net income attributable to SCC ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 2,564.2 Capital investment ​ $ 389.6 ​ $ 61.5 ​ $ 237.6 ​ $ 6.8 ​ $ 695.5 Property and mine development, net ​ $ 4,551.1 ​ $ 555.5 ​ $ 3,713.0 ​ $ 656.5 ​ $ 9,476.1 Total assets ​ $ 8,200.6 ​ $ 1,009.9 ​ $ 4,774.2 ​ $ 4,125.6 ​ $ 18,110.3 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2020 ​ ​ (in millions) ​ ​ Mexican ​ ​ Corporate, other ​ ​ ​ ​ Mexican ​ IMMSA ​ Peruvian ​ and ​ ​ ​ ​ Open-pit ​ Unit ​ Operations ​ eliminations ​ Consolidated Net sales outside of segments ​ $ 1,181.7 ​ $ 111.2 ​ $ 836.2 ​ $ — ​ $ 2,129.1 Intersegment sales ​ — ​ ​ 29.7 ​ — ​ (29.7) ​ — Cost of sales (exclusive of depreciation, amortization and depletion) ​ 491.0 ​ 91.0 ​ 395.1 ​ (28.2) ​ 948.9 Selling, general and administrative ​ 19.1 ​ 2.6 ​ 9.1 ​ 2.6 ​ 33.4 Depreciation, amortization and depletion ​ 91.0 ​ 10.7 ​ 85.4 ​ 8.9 ​ 196.0 Exploration ​ 0.4 ​ 1.8 ​ 1.9 ​ 2.8 ​ 6.9 Operating income ​ $ 580.2 ​ $ 34.8 ​ $ 344.7 ​ $ (15.8) ​ ​ 943.9 Less: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest, net ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (86.4) Other income (expense) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (14.0) Income taxes ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (338.5) Equity earnings of affiliate ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 3.1 Non-controlling interest ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (2.1) Net income attributable to SCC ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 506.0 Capital investment ​ $ 76.0 ​ $ 16.0 ​ $ 41.3 ​ $ 1.2 ​ $ 134.5 Property and mine development, net ​ $ 4,540.5 ​ $ 508.1 ​ $ 3,726.3 ​ $ 369.8 ​ $ 9,144.7 Total assets ​ $ 7,551.0 ​ $ 879.7 ​ $ 5,032.3 ​ $ 2,785.4 ​ $ 16,248.4 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2020 ​ ​ (in millions) ​ ​ Mexican ​ ​ Corporate, other ​ ​ ​ ​ Mexican ​ IMMSA ​ Peruvian ​ and ​ ​ ​ ​ Open-pit ​ Unit ​ Operations ​ eliminations ​ Consolidated Net sales outside of segments ​ $ 3,152.1 ​ $ 299.0 ​ $ 2,183.1 ​ $ — ​ $ 5,634.2 Intersegment sales ​ — ​ 78.0 ​ — ​ (78.0) ​ — Cost of sales (exclusive of depreciation, amortization and depletion) ​ 1,482.4 ​ 285.1 ​ 1,202.0 ​ (88.2) ​ 2,881.3 Selling, general and administrative ​ 55.0 ​ 6.8 ​ 26.5 ​ 5.7 ​ 94.0 Depreciation, amortization and depletion ​ 276.0 ​ 31.6 ​ 247.0 ​ 28.2 ​ 582.8 Exploration ​ 1.9 ​ 6.9 ​ 6.0 ​ 7.0 ​ 21.8 Operating income ​ $ 1,336.8 ​ $ 46.6 ​ $ 701.6 ​ $ (30.7) ​ ​ 2,054.3 Less: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest, net ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (263.0) Other income (expense) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (22.4) Income taxes ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (784.7) Equity earnings of affiliate ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1.0 Non-controlling interest ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (4.9) Net income attributable to SCC ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 980.3 Capital investment ​ $ 179.7 ​ $ 55.7 ​ $ 107.3 ​ $ 6.1 ​ $ 348.8 Property and mine development, net ​ $ 4,540.5 ​ $ 508.1 ​ $ 3,726.3 ​ $ 369.8 ​ $ 9,144.7 Total assets ​ $ 7,551.0 ​ $ 879.7 ​ $ 5,032.3 ​ $ 2,785.4 ​ $ 16,248.4 ​

SUBSEQUENT EVENTS_

SUBSEQUENT EVENTS:	9 Months Ended
	Sep. 30, 2021
SUBSEQUENT EVENTS:
SUBSEQUENT EVENTS:	​ ​ NOTE 15 — SUBSEQUENT EVENTS: ​ Dividends ​ On October 21, 2021, the Board of Directors authorized a dividend of $1.00 per share payable on November 23, 2021 to shareholders of record at the close of business on November 10, 2021. ​

SHORT-TERM INVESTMENTS_ (Tables

SHORT-TERM INVESTMENTS: (Tables)	9 Months Ended
	Sep. 30, 2021
SHORT-TERM INVESTMENTS:
Schedule of short-term investments	​ Short-term investments were as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ At September 30, ​ At December 31, ​ ​ ​ 2021 2020 ​ ​ Trading securities ​ $ 626.4 ​ $ 410.2 ​ ​ Weighted average interest rate ​ 0.2 % 0.4 % ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available-for-sale ​ $ 0.4 ​ $ 0.6 ​ ​ Weighted average interest rate ​ 0.7 % 0.7 % ​ Total ​ $ 626.8 ​ $ 410.8 ​ ​
Summary of activity investments	The following table summarizes the activity of these investments by category (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Nine months ended ​ ​ ​ September 30, ​ September 30, ​ ​ ​ 2021 2020 2021 2020 ​ Trading: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest earned ​ $ 0.6 ​ $ (*) ​ $ 1.3 ​ $ 0.1 ​ ​ Unrealized gain (loss) at the end of the period ​ $ (*) ​ $ (*) ​ $ (*) ​ $ (*) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Available-for-sale: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest earned ​ ​ (*) ​ ​ (*) ​ (*) ​ ​ (*) ​ ​ Investment redeemed ​ $ 0.1 ​ $ — ​ $ 0.2 ​ $ 0.1 ​ ​ (*) Less than $0.1 million.

INVENTORIES_ (Tables)

INVENTORIES: (Tables)	9 Months Ended
	Sep. 30, 2021
INVENTORIES:
Schedule of inventories	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ At September 30, ​ At December 31, ​ (in millions) 2021 2020 ​ Inventory, current: ​ ​ ​ ​ ​ ​ ​ Metals at average cost: ​ ​ ​ ​ ​ ​ ​ Finished goods ​ $ 61.3 ​ $ 50.8 ​ Work-in-process ​ 278.1 ​ 248.9 ​ Ore stockpiles on leach pads ​ ​ 231.0 ​ ​ 298.5 ​ Supplies at average cost ​ 342.1 ​ 352.0 ​ Total current inventory ​ $ 912.5 ​ $ 950.2 ​ Inventory, long-term: ​ ​ ​ ​ ​ ​ ​ Ore stockpiles on leach pads ​ $ 1,171.1 ​ $ 1,125.0 ​

INCOME TAXES_ (Tables)

INCOME TAXES: (Tables)	9 Months Ended
	Sep. 30, 2021
INCOME TAXES:
Schedule of income tax provision and effective income tax rate	​ The income tax provision and the effective income tax rate for the first nine months of 2021 and 2020 consisted of (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ 2021 2020 ​ Statutory income tax provision ​ $ 1,387.0 ​ $ 694.7 ​ Peruvian royalty ​ 70.1 ​ 14.1 ​ Mexican royalty ​ 162.5 ​ 44.1 ​ Peruvian special mining tax ​ 84.2 ​ 31.8 ​ Total income tax provision ​ $ 1,703.8 ​ $ 784.7 ​ ​ ​ ​ ​ ​ ​ ​ ​ Effective income tax rate ​ ​ 40.0 % ​ 44.4 %

RELATED PARTY TRANSACTIONS_ (Ta

RELATED PARTY TRANSACTIONS: (Tables)	9 Months Ended
	Sep. 30, 2021
RELATED PARTY TRANSACTIONS:
Schedule of receivable and payable balances with related parties	​ Receivable and payable balances with related parties are shown below (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ At September 30, ​ At December 31, ​ ​ 2021 2020 ​ Related parties receivable current: ​ ​ ​ ​ ​ ​ ​ Grupo Mexico and affiliates: ​ ​ ​ ​ ​ ​ ​ Asarco LLC ​ $ 7.8 ​ $ 5.3 ​ Compania Perforadora Mexico S.A.P.I. de C.V. and affiliates ​ 0.3 ​ 0.3 ​ Grupo Mexico ​ 2.7 ​ 2.7 ​ Grupo Mexico Servicios ​ ​ 0.1 ​ ​ — ​ Mexico Generadora de Energia S. de R.L. ("MGE") ​ ​ 23.3 ​ ​ 14.4 ​ Grupo Mexico Servicios de Ingenieria, S.A. de C.V. ​ ​ 0.2 ​ ​ 0.2 ​ Related to the controlling group: ​ ​ ​ ​ ​ ​ ​ Boutique Bowling de Mexico, S.A. de C.V. ​ ​ (*) ​ ​ 0.2 ​ Mexico Transportes Aereos, S.A. de C.V. ("Mextransport") ​ ​ 0.2 ​ ​ — ​ Operadora de Cinemas, S.A. de C.V. ​ ​ (*) ​ ​ 0.2 ​ ​ ​ $ 34.6 ​ $ 23.3 ​ ​ ​ ​ ​ ​ ​ ​ ​ Related parties payable: ​ ​ ​ ​ ​ ​ ​ Grupo Mexico and affiliates: ​ ​ ​ ​ ​ ​ ​ Asarco LLC ​ $ 20.4 ​ $ 13.9 ​ Eolica El Retiro, S.A.P.I. de C.V. ​ ​ 5.9 ​ ​ 0.3 ​ Ferrocarril Mexicano, S.A. de C.V. ​ 3.5 ​ 4.7 ​ Grupo Mexico ​ — ​ 0.9 ​ Grupo Mexico Servicios ​ 16.7 ​ 19.6 ​ Grupo Mexico Servicios de Ingenieria, S.A. de C.V. ​ ​ 0.8 ​ ​ 0.7 ​ MGE ​ ​ 50.6 ​ ​ 40.8 ​ Mexico Compania Constructora S.A de C.V. ​ ​ 14.1 ​ ​ 22.9 ​ Related to the controlling group: ​ ​ ​ ​ ​ ​ ​ Boutique Bowling de Mexico, S.A. de C.V. ​ 0.3 ​ 0.3 ​ Mexico Transportes Aereos, S.A. de C.V. (“Mextransport”) ​ 0.3 ​ 0.1 ​ Operadora de Cinemas, S.A. de C.V. ​ ​ 0.1 ​ ​ 0.1 ​ ​ ​ $ 112.7 ​ $ 104.3 ​ (*) Less than $0.1 million.
Grupo Mexico and affiliates
RELATED PARTY TRANSACTIONS:
Schedule of purchase and sales activities with related parties	The following table summarizes the purchase and sale activities with Grupo Mexico and its affiliates in the first nine months of 2021 and 2020 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ 2021 2020 Purchase activity ​ ​ ​ ​ ​ ​ Asarco LLC ​ $ 23.0 ​ $ 224.3 Eolica El Retiro, S.A.P.I. de C.V. ​ 6.2 ​ 0.8 Ferrocarril Mexicano, S.A. de C.V. ​ 33.1 ​ 36.8 Grupo Mexico ​ ​ — ​ ​ 7.5 Grupo Mexico Servicios ​ ​ 21.9 ​ ​ 13.4 Intermodal Mexico S.A. de C.V. ​ ​ 0.5 ​ ​ — MGE ​ 209.0 ​ 157.2 Mexico Proyectos y Desarrollos S.A. de C.V. and affiliates ​ ​ 43.8 ​ ​ 42.4 Peru Mining Exploration & Development Company ​ 0.4 ​ — Total purchases ​ $ 337.9 ​ $ 482.4 Sales activity ​ ​ ​ ​ ​ ​ Asarco LLC ​ $ 22.8 ​ $ 58.6 Grupo Mexico Servicios ​ ​ 0.1 ​ ​ 0.1 MGE ​ ​ 92.3 ​ ​ 37.7 Total sales ​ $ 115.2 ​ $ 96.4
Related to the controlling group
RELATED PARTY TRANSACTIONS:
Schedule of purchase and sales activities with related parties	The following table summarizes the purchase and sales activities with other Larrea family companies in the first nine months of 2021 and 2020 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ 2021 2020 Purchase activity ​ ​ ​ ​ ​ ​ Boutique Bowling de Mexico S.A. de C.V. ​ $ 0.2 ​ $ 0.3 Mextransport ​ ​ 1.1 ​ ​ 3.0 Operadora de Cinemas S.A. de C.V. ​ ​ 0.1 ​ ​ 0.1 Total purchases ​ $ 1.4 ​ $ 3.4 ​ ​ ​ ​ ​ ​ ​ Sales activity ​ ​ ​ ​ ​ ​ Boutique Bowling de Mexico S.A. de C.V. ​ $ (*) ​ $ 0.1 Mextransport ​ ​ 1.4 ​ ​ 1.2 Operadora de Cinemas S.A. de C.V. ​ ​ (*) ​ ​ 0.1 Total sales ​ $ 1.4 ​ $ 1.4

DERIVATIVE INSTRUMENTS_ (Tables

DERIVATIVE INSTRUMENTS: (Tables)	9 Months Ended
	Sep. 30, 2021
DERIVATIVE INSTRUMENTS:
Schedule of derivative instruments	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Call ​ Financial Swap ​ Derivatives designated as hedging instruments under ASC 815 ​ Option ​ Cash Settlement ​ ​ ​ ​ ​ ​ ​ ​ ​ Commodity contracts ​ ​ Natural gas ​ ​ Natural gas ​ Gas volume (MMBTUs) ​ ​ 5,285,000 ​ ​ 5,285,000 ​ Fixed price ($) ​ ​ 3.75 ​ ​ 0.55 ​ Total option premium (millions of $) ​ N/A ​ ​ 2.9 ​ Estimated fair value of assets (liabilities) as of September 30, 2021 (millions of $) ​ 12.1 ​ ​ (2.9) ​ Effect of derivative instruments on the consolidated Statement of Earnings (millions of $) ​ — ​ ​ — ​ (Favorable) unfavorable effect in OCI - net of deferred income taxes (millions of $) ​ ​ (8.4) ​ ​ 2.0 ​

LEASES_ (Tables)

LEASES: (Tables)	9 Months Ended
	Sep. 30, 2021
LEASES:
Schedule of the operating lease expense recognized	The operating lease expense recognized in the first nine months of 2021 and 2020 was classified as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ Classification 2021 2020 Cost of sales (exclusive of depreciation, amortization and depletion) $ 85.8 ​ $ 86.4 Selling, general and administrative ​ 0.1 ​ 0.2 Exploration ​ 0.1 ​ 0.1 Total lease expense $ 86.0 ​ $ 86.7
Schedule of Maturities of lease liabilities	​ ​ ​ ​ ​ ​ ​ Lease liabilities Year (in millions) 2021 $ 28.6 2022 ​ 113.7 2023 ​ 112.4 2024 ​ 104.7 2025 ​ 103.7 After 2025 ​ 723.0 Total lease payments $ 1,186.1 Less: interest on lease liabilities ​ (259.5) Present value of lease payments $ 926.6

ASSET RETIREMENT OBLIGATION_ (T

ASSET RETIREMENT OBLIGATION: (Tables)	9 Months Ended
	Sep. 30, 2021
ASSET RETIREMENT OBLIGATION:
Summary of asset retirement obligation activity	​ The following table summarizes the asset retirement obligation activity for the first nine months of 2021 and 2020 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ 2021 2020 Balance as of January 1 ​ $ 545.0 ​ $ 262.3 Closure payments ​ (3.7) ​ (1.0) Accretion expense ​ 18.3 ​ 11.1 Balance as of September 30, ​ $ 559.6 ​ $ 272.4

BENEFIT PLANS_ (Tables)

BENEFIT PLANS: (Tables)	9 Months Ended
	Sep. 30, 2021
Post retirement defined benefit plans and defined contribution plan
Components of net periodic benefit costs
Schedule of the components of net periodic benefit costs	The components of net periodic benefit costs for the first nine months of 2021 and 2020 are as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ (in millions) 2021 2020 Service cost ​ $ 1.1 ​ $ 1.0 Interest cost ​ 1.2 ​ 1.2 Expected return on plan assets ​ (2.6) ​ (2.1) Amortization of prior service cost / (credit) ​ 0.1 ​ 0.1 Amortization of net loss/(gain) ​ 0.2 ​ 0.2 Net periodic benefit cost ​ $ (0.0) ​ $ 0.4
Post-retirement Health care plans
Components of net periodic benefit costs
Schedule of the components of net periodic benefit costs	​ The components of net periodic benefit cost for the first nine months of 2021 and 2020 are as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ (in millions) 2021 2020 Interest cost ​ $ 1.3 ​ $ 0.9 Amortization of net loss (gain) ​ 0.1 ​ — Amortization of prior service cost/ (credit) ​ — ​ — Net periodic benefit cost ​ $ 1.4 ​ $ 0.9

COMMITMENTS AND CONTINGENCIES_

COMMITMENTS AND CONTINGENCIES: (Tables)	9 Months Ended
	Sep. 30, 2021
COMMITMENTS AND CONTINGENCIES:
Schedule of environmental capital investments	​ Environmental capital investments in the first nine months of 2021 and 2020 were as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ 2021 2020 Peruvian operations (*) ​ $ 2.9 ​ $ (4.0) Mexican operations ​ 57.7 ​ 28.6 ​ ​ $ 60.6 ​ $ 24.6 (*) ​

STOCKHOLDERS' EQUITY (Tables)

STOCKHOLDERS' EQUITY (Tables)	9 Months Ended
	Sep. 30, 2021
Share based Compensation Plan
Schedule of activity in treasury stock	​ Activity in treasury stock in the nine-month period ended September 30, 2021 and 2020 is as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ 2021 2020 Southern Copper common shares ​ ​ ​ ​ ​ ​ Balance as of January 1, ​ $ 2,767.5 ​ $ 2,767.9 Used for corporate purposes ​ (0.1) ​ (0.4) Balance as of September 30, ​ 2,767.4 ​ 2,767.5 ​ ​ ​ ​ ​ ​ ​ Parent Company (Grupo Mexico) common shares ​ ​ ​ ​ ​ ​ Balance as of January 1, ​ 296.0 ​ 281.0 Other activity, including dividend, interest and foreign currency transaction effect ​ 17.4 ​ (0.5) Balance as of September 30, ​ 313.4 ​ 280.5 Treasury stock balance as of September 30, ​ $ 3,080.8 ​ $ 3,048.0
Summary of non-controlling interest activity	The following table presents the non-controlling interest activity for the nine months ended September 30, 2021 and 2020 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ 2021 2020 Balance as of January 1, $ 51.2 $ 47.9 Net earnings ​ 10.6 ​ 4.9 Dividend paid ​ (4.4) ​ (2.8) Balance as of September 30, $ 57.4 $ 50.0
Employee Stock Purchase 2015 Plan
Share based Compensation Plan
Schedule of stock based compensation expense and unrecognized compensation expense	​ The stock based compensation expense for the first nine months of 2021 and 2020 and the unrecognized compensation expense under this plan were as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ 2021 2020 Stock based compensation expense ​ $ 0.5 ​ $ 0.5 Unrecognized compensation expense ​ $ 1.0 ​ $ 1.5 ​
Schedule of stock award activity	​ ​ ​ ​ ​ ​ ​ ​ ​ Unit Weighted Average ​ ​ Shares ​ Grant Date Fair Value Outstanding shares at January 1, 2021 1,264,410 ​ $ 2.63 Granted — ​ — Exercised (381,288) ​ $ 2.63 Forfeited — ​ — Outstanding shares at September 30, 2021 883,122 ​ $ 2.63 Outstanding shares at January 1, 2020 1,379,734 ​ $ 2.63 Granted — ​ — Exercised (54,221) ​ $ 2.63 Forfeited — ​ — Outstanding shares at September 30, 2020 1,325,513 ​ $ 2.63 ​
Employee Stock Purchase 2018 Plan
Share based Compensation Plan
Schedule of stock based compensation expense and unrecognized compensation expense	​ The stock based compensation expense for the nine months ended September 30, 2021 and 2020 and the unrecognized compensation expense under this plan were as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ 2021 ​ 2020 Stock based compensation expense ​ $ 0.5 $ 0.5 Unrecognized compensation expense ​ $ 3.3 $ 4.0 ​
Schedule of stock award activity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unit Weighted Average ​ Shares Grant Date Fair Value Outstanding shares at January 1, 2021 3,918,458 $ 1.86 Granted — ​ — Exercised (716,449) $ 1.86 Forfeited — ​ — Outstanding shares at September 30, 2021 3,202,009 $ 1.86 Outstanding shares at January 1, 2020 ​ 4,002,898 $ 1.86 Granted ​ — ​ — Exercised ​ (37,940) $ 1.86 Forfeited ​ — ​ — Outstanding shares at September 30, 2020 3,964,958 $ 1.86

FAIR VALUE MEASUREMENT_ (Tables

FAIR VALUE MEASUREMENT: (Tables)	9 Months Ended
	Sep. 30, 2021
FAIR VALUE MEASUREMENT:
Schedule of carrying amount and estimated fair values of the Company's financial instruments	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ At September 30, 2021 ​ At December 31, 2020 ​ Carrying Value Fair Value Carrying Value Fair Value Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Long-term debt level 1 ​ ​ 6,195.8 ​ ​ 8,124.6 ​ ​ 6,193.6 ​ ​ 8,692.1 Long-term debt level 2 ​ ​ 350.9 ​ ​ 378.4 ​ ​ 350.6 ​ ​ 385.7 Total long-term debt ​ $ 6,546.7 ​ $ 8,503.0 ​ $ 6,544.2 ​ $ 9,077.8
Schedule of fair values of assets and liabilities measured at fair value on a recurring basis	Fair values of assets and liabilities measured at fair value on a recurring basis were calculated as follows as of September 30, 2021 and December 31, 2020 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value at Measurement Date Using: ​ ​ ​ ​ ​ Significant ​ ​ ​ ​ Fair Value ​ Quoted prices in ​ other ​ Significant ​ ​ as of ​ active markets for ​ observable ​ unobservable ​ ​ September 30, ​ identical assets ​ inputs ​ inputs Description ​ 2021 ​ (Level 1) ​ (Level 2) ​ (Level 3) Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Short term investment: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — ​ $ 626.4 ​ $ 626.4 ​ $ — ​ $ — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate bonds ​ — ​ ​ — ​ ​ — ​ ​ — Asset backed securities ​ 0.2 ​ ​ — ​ ​ 0.2 ​ ​ — Mortgage backed securities ​ 0.2 ​ ​ — ​ ​ 0.2 ​ ​ — Accounts receivable: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Provisionally priced sales: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Copper ​ 707.1 ​ 707.1 ​ ​ — ​ ​ — Molybdenum ​ 281.7 ​ 281.7 ​ — ​ ​ — Total ​ $ 1,615.6 ​ $ 1,615.2 ​ $ 0.4 ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value at Measurement Date Using: ​ ​ ​ ​ ​ Significant ​ ​ ​ ​ Fair Value ​ Quoted prices in ​ other ​ Significant ​ ​ as of ​ active markets for ​ observable ​ unobservable ​ ​ December 31, ​ identical assets ​ inputs ​ inputs Description ​ 2020 ​ (Level 1) ​ (Level 2) ​ (Level 3) Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Short term investment: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — ​ $ 410.2 ​ $ 410.2 ​ $ — ​ $ — — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate bonds ​ — ​ ​ — ​ ​ — ​ ​ — Asset backed securities ​ 0.3 ​ ​ — ​ 0.3 ​ ​ — Mortgage backed securities ​ 0.3 ​ ​ — ​ ​ 0.3 ​ ​ — Accounts receivable: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Provisionally priced sales: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Copper ​ 491.9 ​ 491.9 ​ ​ — ​ ​ — Molybdenum ​ 129.2 ​ 129.2 ​ — ​ ​ — Total ​ $ 1,031.9 ​ $ 1,031.3 ​ $ 0.6 ​ $ —

REVENUE_ (Tables)

REVENUE: (Tables)	9 Months Ended
	Sep. 30, 2021
REVENUE:
Summary of company's sales by geographic wise and segment wise	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2021 ​ ​ ​ ​ Mexican ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mexican ​ IMMSA ​ Peruvian ​ Corporate & ​ ​ ​ ​ Open-Pit Unit Operations Elimination Consolidated The Americas: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mexico ​ $ 483.1 ​ $ 115.7 ​ $ 4.5 ​ $ (42.8) ​ $ 560.5 United States ​ 324.9 ​ 11.2 ​ 71.3 ​ — ​ 407.4 Peru ​ — ​ (0.4) ​ 148.3 ​ — ​ 147.9 Brazil ​ — ​ 10.9 ​ 93.2 ​ — ​ 104.1 Chile ​ (0.1) ​ — ​ 113.8 ​ — ​ 113.7 Other American countries ​ 10.9 ​ — ​ 1.8 ​ — ​ 12.7 Europe: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Switzerland ​ 276.0 ​ 20.3 ​ 127.6 ​ — ​ 423.9 Italy ​ — ​ 3.9 ​ 62.9 ​ — ​ 66.8 Spain ​ 106.6 ​ — ​ 20.4 ​ — ​ 127.0 Other European countries ​ 54.2 ​ 7.0 ​ 110.9 ​ — ​ 172.1 Asia: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Singapore ​ 119.9 ​ 6.3 ​ 159.7 ​ — ​ 285.9 Japan ​ (0.8) ​ — ​ 167.7 ​ — ​ 166.9 Other Asian countries ​ 51.1 ​ 0.2 ​ 40.7 ​ — ​ 92.0 Total ​ $ 1,425.8 ​ $ 175.1 ​ $ 1,122.8 ​ $ (42.8) ​ $ 2,680.9 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2021 ​ ​ ​ ​ Mexican ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mexican ​ IMMSA ​ Peruvian ​ Corporate & ​ ​ ​ ​ Open-Pit Unit Operations Elimination Consolidated The Americas: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mexico ​ $ 1,431.7 ​ $ 291.8 ​ $ 4.5 ​ $ (107.9) ​ $ 1,620.1 United States ​ 1,107.5 ​ 42.9 ​ 152.2 ​ — ​ 1,302.6 Peru ​ — ​ (0.3) ​ 438.9 ​ — ​ 438.6 Brazil ​ — ​ 18.4 ​ 310.8 ​ — ​ 329.2 Chile ​ 2.8 ​ — ​ 265.1 ​ — ​ 267.9 Other American countries ​ 28.9 ​ 0.7 ​ 4.6 ​ — ​ 34.2 Europe: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Switzerland ​ 888.7 ​ 46.0 ​ 323.1 ​ — ​ 1,257.8 Italy ​ 0.2 ​ 5.9 ​ 244.8 ​ — ​ 250.9 Spain ​ 299.8 ​ — ​ 63.8 ​ — ​ 363.6 Other European countries ​ 202.2 ​ 40.3 ​ 310.8 ​ — ​ 553.3 Asia: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Singapore ​ 354.8 ​ 14.8 ​ 395.7 ​ — ​ 765.3 Japan ​ 23.6 ​ — ​ 478.1 ​ — ​ 501.7 Other Asian countries ​ 196.4 ​ 0.3 ​ 228.5 ​ — ​ 425.2 Total ​ $ 4,536.6 ​ $ 460.8 ​ $ 3,220.9 ​ $ (107.9) ​ $ 8,110.4 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2020 ​ ​ ​ ​ ​ Mexican ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mexican ​ IMMSA ​ Peruvian ​ Corporate & ​ ​ ​ ​ Open-Pit Unit Operations Elimination Consolidated The Americas: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mexico ​ $ 319.5 ​ $ 84.5 ​ $ — ​ $ (29.7) ​ $ 374.3 United States ​ 309.9 ​ 11.3 ​ 33.6 ​ — ​ ​ 354.8 Peru ​ — ​ 4.8 ​ 95.1 ​ — ​ ​ 99.9 Brazil ​ — ​ 6.7 ​ 58.9 ​ — ​ ​ 65.6 Chile ​ — ​ — ​ 55.4 ​ — ​ ​ 55.4 Other American countries ​ 16.9 ​ 0.7 ​ 1.0 ​ — ​ ​ 18.6 Europe: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Switzerland ​ ​ 274.0 ​ 19.2 ​ 153.4 ​ — ​ ​ 446.6 Italy ​ ​ — ​ 2.0 ​ 60.2 ​ — ​ ​ 62.2 Spain ​ ​ 62.5 ​ — ​ — ​ — ​ ​ 62.5 Other European countries ​ ​ 42.4 ​ 11.0 ​ 83.2 ​ — ​ ​ 136.6 Asia: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Singapore ​ ​ 55.9 ​ 0.6 ​ 136.2 ​ — ​ ​ 192.7 Japan ​ ​ 15.2 ​ — ​ 129.1 ​ — ​ ​ 144.3 Other Asian countries ​ ​ 85.4 ​ 0.1 ​ 30.1 ​ — ​ ​ 115.6 Total ​ $ 1,181.7 ​ $ 140.9 ​ $ 836.2 ​ $ (29.7) ​ $ 2,129.1 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2020 ​ ​ ​ ​ ​ Mexican ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mexican ​ IMMSA ​ Peruvian ​ Corporate & ​ ​ ​ ​ Open-Pit Unit Operations Elimination Consolidated The Americas: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mexico ​ $ 890.3 ​ $ 254.2 ​ $ — ​ $ (78.0) ​ $ 1,066.5 United States ​ 866.8 ​ 15.5 ​ 94.0 ​ — ​ ​ 976.3 Peru ​ — ​ 10.4 ​ 208.2 ​ — ​ ​ 218.6 Brazil ​ — ​ 11.6 ​ 134.3 ​ — ​ ​ 145.9 Chile ​ 19.5 ​ — ​ 144.7 ​ — ​ ​ 164.2 Other American countries ​ 25.9 ​ 2.1 ​ 1.4 ​ — ​ ​ 29.4 Europe: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Switzerland ​ ​ 682.6 ​ 50.1 ​ 367.7 ​ — ​ ​ 1,100.4 Italy ​ ​ — ​ 6.3 ​ 179.1 ​ — ​ ​ 185.4 Spain ​ ​ 127.3 ​ — ​ — ​ — ​ ​ 127.3 Other European countries ​ ​ 118.8 ​ 20.7 ​ 203.1 ​ — ​ ​ 342.6 Asia: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Singapore ​ ​ 233.9 ​ 5.7 ​ 383.0 ​ — ​ ​ 622.6 Japan ​ ​ 26.9 ​ — ​ 365.9 ​ — ​ ​ 392.8 Other Asian countries ​ ​ 160.1 ​ 0.4 ​ 101.7 ​ — ​ ​ 262.2 Total ​ $ 3,152.1 ​ $ 377.0 ​ $ 2,183.1 ​ $ (78.0) ​ $ 5,634.2 ​ The following table presents information regarding the sales value by reporting segment of the Company’s significant products for the three and nine months ended September 30, 2021 and 2020 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2021 ​ ​ ​ Mexican ​ ​ ​ ​ ​ ​ ​ ​ Mexican IMMSA Peruvian Corporate, Other & Total ​ ​ Open-pit ​ Unit ​ Operations ​ Eliminations ​ Consolidated Copper ​ $ 1,195.0 ​ $ 24.3 ​ $ 912.9 ​ $ (21.8) ​ $ 2,110.4 Molybdenum ​ 146.6 ​ — ​ 147.9 ​ — ​ 294.5 Silver ​ 52.4 ​ 37.2 ​ 33.6 ​ (19.0) ​ 104.2 Zinc ​ — ​ 98.6 ​ — ​ 0.1 ​ 98.7 Other ​ 31.8 ​ 15.0 ​ 28.4 ​ (2.1) ​ 73.1 Total ​ $ 1,425.8 ​ $ 175.1 ​ $ 1,122.8 ​ $ (42.8) ​ $ 2,680.9 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2021 ​ ​ ​ Mexican ​ ​ ​ ​ ​ ​ ​ ​ Mexican IMMSA Peruvian Corporate, Other & Total ​ ​ Open-pit ​ Unit ​ Operations ​ Eliminations ​ Consolidated Copper ​ $ 3,858.2 ​ $ 75.5 ​ $ 2,697.1 ​ $ (54.7) ​ $ 6,576.1 Molybdenum ​ 387.3 ​ — ​ 359.0 ​ — ​ 746.3 Silver ​ 193.1 ​ 122.6 ​ 95.8 ​ ​ (48.1) ​ 363.4 Zinc ​ — ​ 215.1 ​ — ​ 0.5 ​ 215.6 Other ​ 98.0 ​ 47.6 ​ 69.0 ​ (5.6) ​ 209.0 Total ​ $ 4,536.6 ​ $ 460.8 ​ $ 3,220.9 ​ $ (107.9) ​ $ 8,110.4 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2020 ​ ​ ​ Mexican ​ ​ ​ ​ ​ ​ ​ ​ Mexican IMMSA Peruvian Corporate, Other & Total ​ ​ Open-pit ​ Unit ​ Operations ​ Eliminations ​ Consolidated Copper ​ $ 1,022.1 ​ $ 21.2 ​ $ 720.7 ​ $ (14.1) ​ $ 1,749.9 Molybdenum ​ 58.2 ​ — ​ 61.6 ​ — ​ 119.8 Silver ​ 67.0 ​ 48.4 ​ 35.1 ​ (17.5) ​ 133.0 Zinc ​ — ​ 57.6 ​ — ​ 4.6 ​ 62.2 Other ​ 34.4 ​ 13.7 ​ 18.8 ​ (2.7) ​ 64.2 Total ​ $ 1,181.7 ​ $ 140.9 ​ $ 836.2 ​ $ (29.7) ​ $ 2,129.1 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2020 ​ ​ ​ Mexican ​ ​ ​ ​ ​ ​ ​ ​ Mexican IMMSA Peruvian Corporate, Other & Total ​ ​ Open-pit ​ Unit ​ Operations ​ Eliminations ​ Consolidated Copper ​ $ 2,687.8 ​ $ 50.9 ​ $ 1,881.4 ​ $ (34.7) ​ $ 4,585.4 Molybdenum ​ 188.3 ​ — ​ 164.5 ​ — ​ 352.8 Silver ​ 170.6 ​ 111.1 ​ 77.6 ​ ​ (38.9) ​ 320.4 Zinc ​ — ​ 174.1 ​ — ​ 1.3 ​ 175.4 Other ​ 105.4 ​ 40.9 ​ 59.6 ​ (5.7) ​ 200.2 Total ​ $ 3,152.1 ​ $ 377.0 ​ $ 2,183.1 ​ $ (78.0) ​ $ 5,634.2 ​ ​
Schedule of opening and closing balances of receivables by reporting segment	The opening and closing balances of receivables by reporting segment of the Company were as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mexican ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mexican IMMSA Peruvian Corporate & ​ ​ ​ ​ Open-Pit ​ Unit ​ Operations ​ Elimination ​ Consolidated ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of September 30, 2021: ​ ​ ​ ​ ​ Trade receivables ​ $ 658.8 ​ $ 57.1 ​ $ 777.5 ​ $ — ​ $ 1,493.4 Related parties, current ​ 25.1 ​ — ​ 1.7 ​ 7.8 ​ 34.6 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2020: ​ ​ ​ ​ ​ Trade receivables ​ $ 566.0 ​ $ 57.8 ​ $ 445.1 ​ $ — ​ $ 1,068.9 Related parties, current ​ 15.4 ​ — ​ 0.8 ​ 7.1 ​ 23.3
Schedule long term contracts by products	As of September 30, 2021, the Company has long-term contracts with promises to deliver the following products in 2021: ​ ​ ​ ​ Copper concentrates (in tons) 188,000 Copper cathodes (in tons) ​ 48,000 Molybdenum concentrates (in tons) 41,414 Sulfuric acid (in tons) 322,415 ​
Schedule of provisionally priced copper and molybdenum sales outstanding	Following are the provisionally priced copper and molybdenum sales outstanding at September 30, 2021: ​ ​ ​ ​ ​ ​ ​ ​ ​ Sales volume Priced at ​ ​ ​ (million lbs.) ​ (per pound) ​ Month of settlement Copper ​ 174.1 ​ 4.06 ​ October 2021 through February 2022 Molybdenum ​ 15.3 ​ 18.45 ​ October 2021 through December 2021

SEGMENT AND RELATED INFORMATI_2

SEGMENT AND RELATED INFORMATION: (Tables)	9 Months Ended
	Sep. 30, 2021
SEGMENT AND RELATED INFORMATION:
Schedule of financial information relating to Company's segments	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2021 ​ ​ (in millions) ​ ​ Mexican ​ ​ Corporate, other ​ ​ ​ ​ Mexican ​ IMMSA ​ Peruvian ​ and ​ ​ ​ ​ ​ Open-pit ​ Unit ​ Operations ​ eliminations ​ Consolidated Net sales outside of segments ​ $ 1,425.8 ​ $ 132.3 ​ $ 1,122.8 ​ $ — ​ $ 2,680.9 Intersegment sales ​ — ​ ​ 42.8 ​ — ​ (42.8) ​ — Cost of sales (exclusive of depreciation, amortization and depletion) ​ 433.4 ​ 135.8 ​ 406.7 ​ (48.4) ​ 927.5 Selling, general and administrative ​ 17.4 ​ 2.9 ​ 8.1 ​ 2.9 ​ 31.3 Depreciation, amortization and depletion ​ 97.8 ​ 12.7 ​ 83.5 ​ 9.4 ​ 203.4 Exploration ​ 0.6 ​ 1.7 ​ 2.7 ​ 5.9 ​ 10.9 Operating income ​ $ 876.6 ​ $ 22.0 ​ $ 621.8 ​ $ (12.6) ​ ​ 1,507.8 Less: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest, net ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (87.4) Other income (expense) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1.9) Income taxes ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (548.6) Equity earnings of affiliate ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1.3 Non-controlling interest ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (3.6) Net income attributable to SCC ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 867.6 Capital investment ​ $ 114.6 ​ $ 29.0 ​ $ 97.2 ​ $ 2.3 ​ $ 243.1 Property and mine development, net ​ $ 4,551.1 ​ $ 555.5 ​ $ 3,713.0 ​ $ 656.5 ​ $ 9,476.1 Total assets ​ $ 8,200.6 ​ $ 1,009.9 ​ $ 4,774.2 ​ $ 4,125.6 ​ $ 18,110.3 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2021 ​ ​ (in millions) ​ ​ Mexican ​ ​ Corporate, other ​ ​ ​ ​ Mexican ​ IMMSA ​ Peruvian ​ and ​ ​ ​ ​ ​ Open-pit ​ Unit ​ Operations ​ eliminations ​ Consolidated Net sales outside of segments ​ $ 4,536.6 ​ $ 352.9 ​ $ 3,220.9 ​ $ — ​ $ 8,110.4 Intersegment sales ​ — ​ 107.9 ​ — ​ (107.9) ​ — Cost of sales (exclusive of depreciation, amortization and depletion) ​ 1,441.6 ​ 328.8 ​ 1,208.9 ​ (122.5) ​ 2,856.8 Selling, general and administrative ​ 49.7 ​ 7.8 ​ 27.0 ​ 8.4 ​ 92.9 Depreciation, amortization and depletion ​ 289.0 ​ 39.4 ​ 242.6 ​ 28.4 ​ 599.4 Exploration ​ 1.8 ​ 3.8 ​ 9.9 ​ 11.2 ​ 26.7 Operating income ​ $ 2,754.5 ​ $ 81.0 ​ $ 1,732.5 ​ $ (33.4) ​ ​ 4,534.6 Less: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest, net ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (262.6) Other income (expense) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (7.8) Income taxes ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1,703.8) Equity earnings of affiliate ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 14.4 Non-controlling interest ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (10.6) Net income attributable to SCC ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 2,564.2 Capital investment ​ $ 389.6 ​ $ 61.5 ​ $ 237.6 ​ $ 6.8 ​ $ 695.5 Property and mine development, net ​ $ 4,551.1 ​ $ 555.5 ​ $ 3,713.0 ​ $ 656.5 ​ $ 9,476.1 Total assets ​ $ 8,200.6 ​ $ 1,009.9 ​ $ 4,774.2 ​ $ 4,125.6 ​ $ 18,110.3 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2020 ​ ​ (in millions) ​ ​ Mexican ​ ​ Corporate, other ​ ​ ​ ​ Mexican ​ IMMSA ​ Peruvian ​ and ​ ​ ​ ​ Open-pit ​ Unit ​ Operations ​ eliminations ​ Consolidated Net sales outside of segments ​ $ 1,181.7 ​ $ 111.2 ​ $ 836.2 ​ $ — ​ $ 2,129.1 Intersegment sales ​ — ​ ​ 29.7 ​ — ​ (29.7) ​ — Cost of sales (exclusive of depreciation, amortization and depletion) ​ 491.0 ​ 91.0 ​ 395.1 ​ (28.2) ​ 948.9 Selling, general and administrative ​ 19.1 ​ 2.6 ​ 9.1 ​ 2.6 ​ 33.4 Depreciation, amortization and depletion ​ 91.0 ​ 10.7 ​ 85.4 ​ 8.9 ​ 196.0 Exploration ​ 0.4 ​ 1.8 ​ 1.9 ​ 2.8 ​ 6.9 Operating income ​ $ 580.2 ​ $ 34.8 ​ $ 344.7 ​ $ (15.8) ​ ​ 943.9 Less: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest, net ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (86.4) Other income (expense) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (14.0) Income taxes ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (338.5) Equity earnings of affiliate ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 3.1 Non-controlling interest ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (2.1) Net income attributable to SCC ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 506.0 Capital investment ​ $ 76.0 ​ $ 16.0 ​ $ 41.3 ​ $ 1.2 ​ $ 134.5 Property and mine development, net ​ $ 4,540.5 ​ $ 508.1 ​ $ 3,726.3 ​ $ 369.8 ​ $ 9,144.7 Total assets ​ $ 7,551.0 ​ $ 879.7 ​ $ 5,032.3 ​ $ 2,785.4 ​ $ 16,248.4 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2020 ​ ​ (in millions) ​ ​ Mexican ​ ​ Corporate, other ​ ​ ​ ​ Mexican ​ IMMSA ​ Peruvian ​ and ​ ​ ​ ​ Open-pit ​ Unit ​ Operations ​ eliminations ​ Consolidated Net sales outside of segments ​ $ 3,152.1 ​ $ 299.0 ​ $ 2,183.1 ​ $ — ​ $ 5,634.2 Intersegment sales ​ — ​ 78.0 ​ — ​ (78.0) ​ — Cost of sales (exclusive of depreciation, amortization and depletion) ​ 1,482.4 ​ 285.1 ​ 1,202.0 ​ (88.2) ​ 2,881.3 Selling, general and administrative ​ 55.0 ​ 6.8 ​ 26.5 ​ 5.7 ​ 94.0 Depreciation, amortization and depletion ​ 276.0 ​ 31.6 ​ 247.0 ​ 28.2 ​ 582.8 Exploration ​ 1.9 ​ 6.9 ​ 6.0 ​ 7.0 ​ 21.8 Operating income ​ $ 1,336.8 ​ $ 46.6 ​ $ 701.6 ​ $ (30.7) ​ ​ 2,054.3 Less: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest, net ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (263.0) Other income (expense) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (22.4) Income taxes ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (784.7) Equity earnings of affiliate ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 1.0 Non-controlling interest ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (4.9) Net income attributable to SCC ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 980.3 Capital investment ​ $ 179.7 ​ $ 55.7 ​ $ 107.3 ​ $ 6.1 ​ $ 348.8 Property and mine development, net ​ $ 4,540.5 ​ $ 508.1 ​ $ 3,726.3 ​ $ 369.8 ​ $ 9,144.7 Total assets ​ $ 7,551.0 ​ $ 879.7 ​ $ 5,032.3 ​ $ 2,785.4 ​ $ 16,248.4

DESCRIPTION OF THE BUSINESS_ (D

DESCRIPTION OF THE BUSINESS: (Details)	9 Months Ended
	Sep. 30, 2021$ / lb$ / item
Percentage of ownership interest held by the parent company	88.90%
Percentage of operating over production capacity during COVID-19 time	96.00%
Copper price assumption | $ / lb	2
Molybdenum price assumption | $ / item	4
Minimum
Projected discounted cash flows in excess of the carrying amounts of long lived assets by margins	1.3
Maximum
Projected discounted cash flows in excess of the carrying amounts of long lived assets by margins	4.3
Peru
Percentage workforce working on site under strict safety measures	71.00%
Mexico
Percentage workforce working on site under strict safety measures	96.00%

SHORT-TERM INVESTMENTS_ (Detail

SHORT-TERM INVESTMENTS: (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Short-term investment:
Trading securities	$ 626.4		$ 626.4		$ 410.2
Weighted average interest rate (as a percent)			0.20%		0.40%
Available-for-sale	0.4		$ 0.4		$ 0.6
Weighted average interest rate (as a percent)			0.70%		0.70%
Total	626.8		$ 626.8		$ 410.8
Trading:
Interest earned	0.6		1.3	$ 0.1
Available-for-sale:
Interest earned	1.5	$ 2.8	5.2	14.9
Investment redeemed	0.1		0.2	0.1
Maximum
Available-for-sale:
Interest earned	$ 0.1	$ 0.1	$ 0.1	$ 0.1

INVENTORIES_ (Details)

INVENTORIES: (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Metals at average cost:
Finished goods	$ 61.3		$ 50.8
Work-in-process	278.1		248.9
Ore stockpiles on leach pads	231		298.5
Supplies at average cost	342.1		352
Total current inventory	912.5		950.2
Inventory, long-term:
Ore stockpiles on leach pads	1,171.1		$ 1,125
Total leaching costs added as long-term inventory of ore stockpiles in leach pads	184.2	$ 144
Long-term leaching inventories recognized as cost of sales	$ 205.7	$ 287.3

INCOME TAXES_ (Details)

INCOME TAXES: (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Taxes
Statutory income tax provision			$ 1,387	$ 694.7
Peruvian royalty			70.1	14.1
Mexican royalty			162.5	44.1
Peruvian special mining tax			84.2	31.8
Total income tax provision	$ 548.6	$ 338.5	$ 1,703.8	$ 784.7
Effective income tax rate (as a percent)			40.00%	44.40%
Peru
Income Taxes
Peruvian royalty			$ 70.1	$ 14.1
Royalty charges			105.6	39.7
Accrued special mining tax			84.2	31.8
Mexico
Income Taxes
Mexican royalty			$ 162.5	$ 44.1

RELATED PARTY TRANSACTIONS_ (De

RELATED PARTY TRANSACTIONS: (Details) $ in Millions	1 Months Ended	9 Months Ended		12 Months Ended
	May 31, 2020USD ($)	Sep. 30, 2021USD ($)item	Sep. 30, 2020USD ($)	Dec. 31, 2012itemMW	Dec. 31, 2020USD ($)	Sep. 30, 2019USD ($)	Aug. 04, 2014item
RELATED PARTY TRANSACTIONS:
Related parties receivable current:		$ 34.6			$ 23.3
Related parties payable:		112.7			104.3
Total purchases		1.4	$ 3.4
Total sales		1.4	1.4
Minimum
RELATED PARTY TRANSACTIONS:
Aggregate consideration of Material Affiliate Transaction to be be authorized by the General Counsel and CFO		8
Maximum
RELATED PARTY TRANSACTIONS:
Aggregate consideration of Material Affiliate Transaction to be be authorized by the General Counsel and CFO		10
Grupo Mexico and affiliates
RELATED PARTY TRANSACTIONS:
Total purchases		337.9	482.4
Total sales		115.2	96.4
Asarco LLC
RELATED PARTY TRANSACTIONS:
Related parties receivable current:		7.8			5.3
Related parties payable:		20.4			13.9
Total purchases		23	224.3
Total sales		22.8	58.6
Accounts Receivable						$ 62
Making quarterly payments		$ 0.5
Interest Income, Related Party			1.8
Asarco LLC | London Interbank Offered Rate (LIBOR) [Member]
RELATED PARTY TRANSACTIONS:
Debt Instrument, Basis Spread on Variable Rate		2.00%
Compania Perforadora Mexico, S.A.P.I. de C.V. and affiliates
RELATED PARTY TRANSACTIONS:
Related parties receivable current:		$ 0.3			0.3
Eolica El Retiro, S.A.P.I. de C.V.
RELATED PARTY TRANSACTIONS:
Related parties payable:		5.9			0.3
Total purchases		$ 6.2	$ 0.8
Number of wind turbines | item							37
Percentage of supply to third-party energy users		61.00%	11.50%
Ferrocarril Mexicano, S.A. de C.V.
RELATED PARTY TRANSACTIONS:
Related parties payable:		$ 3.5			4.7
Total purchases		33.1	$ 36.8
Grupo Mexico
RELATED PARTY TRANSACTIONS:
Related parties receivable current:		2.7			2.7
Related parties payable:					0.9
Total purchases			7.5
Donations		1.3	7
Grupo Mexico Servicios
RELATED PARTY TRANSACTIONS:
Related parties receivable current:		0.1
Related parties payable:		16.7			19.6
Total purchases		21.9	13.4
Total sales		0.1	0.1
Intermodal Mexico S.A. de C.V.
RELATED PARTY TRANSACTIONS:
Total purchases		0.5
Mexico Generadora de Energia, S. de R.L. ("MGE")
RELATED PARTY TRANSACTIONS:
Related parties receivable current:		23.3			14.4
Related parties payable:		50.6			40.8
Total purchases		209	157.2
Total sales		$ 92.3	$ 37.7
Accounts Receivable	$ 97.2
Making quarterly payments	$ 5.1
Debt Instrument, Basis Spread on Variable Rate	8.28%
Mexico Generadora de Energia, S. de R.L. ("MGE") | Mexico
RELATED PARTY TRANSACTIONS:
Number of natural gas-fired combined cycle power generating units | item				2
Net total capacity (in megawatts) | MW				516.2
Percentage of supply to third-party energy users		2.70%	2.60%
Mexico Compania Constructora S.A de C.V.
RELATED PARTY TRANSACTIONS:
Related parties payable:		$ 14.1			22.9
Mexico Proyectos y Desarrollos, S.A. de C.V. and affiliates ("MPD")
RELATED PARTY TRANSACTIONS:
Related parties receivable current:		0.2			0.2
Related parties payable:		0.8			0.7
Mexico Proyectos y Desarrollos SA de CV and affiliates
RELATED PARTY TRANSACTIONS:
Total purchases		43.8	$ 42.4
Peru Mining Exploration And Development Company
RELATED PARTY TRANSACTIONS:
Total purchases		$ 0.4
Number of mining concessions purchased | item		3
Apu Coropuna S.R.L.
RELATED PARTY TRANSACTIONS:
Ownership percentage		30.00%
Boutique Bowling de Mexico, S.A. de C.V.
RELATED PARTY TRANSACTIONS:
Related parties receivable current:					0.2
Related parties payable:		$ 0.3			0.3
Total purchases		0.2	0.3
Total sales			0.1
Mexico Transportes Aereos, S.A. de C.V. ("Mextransport")
RELATED PARTY TRANSACTIONS:
Related parties receivable current:		0.2
Related parties payable:		0.3			0.1
Total purchases		1.1	3
Total sales		1.4	1.2
Operadora de Cinemas S.A. de C.V.
RELATED PARTY TRANSACTIONS:
Related parties receivable current:					0.2
Related parties payable:		0.1			$ 0.1
Total purchases		0.1	0.1
Total sales			$ 0.1
Operadora de Cinemas S.A. de C.V. | Maximum
RELATED PARTY TRANSACTIONS:
Related parties receivable current:		0.1
Total sales		$ 0.1
Equity investment in affiliate
RELATED PARTY TRANSACTIONS:
Ownership percentage		44.20%

DERIVATIVE INSTRUMENTS_ (Detail

DERIVATIVE INSTRUMENTS: (Details) $ in Millions	9 Months Ended
	Sep. 30, 2021USD ($)MMBblsitem$ / item	Dec. 31, 2020item
Derivatives designated as hedging instruments under ASC 815
Number of derivative contracts entered | item	2
Derivative instruments held | item		0
Call Option | Natural Gas | Derivatives designated as hedging instruments
Derivatives designated as hedging instruments under ASC 815
Gas volume (MMBTUs) | MMBbls	5,285,000
Fixed price ($) | $ / item	3.75
Estimated fair value of assets (liabilities) as of September 30, 2021 (millions of $)	$ 12.1
(Favorable) unfavorable effect in OCI - net of deferred income taxes (millions of $)	$ (8.4)
Swap contracts | Natural Gas | Derivatives designated as hedging instruments
Derivatives designated as hedging instruments under ASC 815
Gas volume (MMBTUs) | MMBbls	5,285,000
Fixed price ($) | $ / item	0.55
Total option premium (millions of $) | $ / item	2.9
Estimated fair value of assets (liabilities) as of September 30, 2021 (millions of $)	$ (2.9)
(Favorable) unfavorable effect in OCI - net of deferred income taxes (millions of $)	$ 2

LEASES_ (Details)

LEASES: (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Leases
Lessee, operating lease, option to extend	false
Lessee, operating lease, option to terminate	false
The weighted average remaining lease term	8 years
The weighted average discount rate	3.74%
Total lease expense	$ 86	$ 86.7
Maturities of lease liabilities
2021	28.6
2022	113.7
2023	112.4
2024	104.7
2025	103.7
After 2025	723
Total lease payments	1,186.1
Less: interest on lease liabilities	(259.5)
Lease liabilities	926.6
Cost of sales (exclusive of depreciation, amortization and depletion)
Leases
Total lease expense	85.8	86.4
Selling, general and administrative
Leases
Total lease expense	0.1	0.2
Exploration
Leases
Total lease expense	$ 0.1	$ 0.1
Minimum
Leases
Remaining lease terms	1 year
Maximum
Leases
Remaining lease terms	11 years

ASSET RETIREMENT OBLIGATION_ (D

ASSET RETIREMENT OBLIGATION: (Details) $ in Millions	9 Months Ended		12 Months Ended
	Sep. 30, 2021USD ($)item	Sep. 30, 2020USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
ASSET RETIREMENT OBLIGATION:
Maximum annual guarantees secured	50.00%
Percentage of guarantee for Lima complex	50.00%
Percentage of security for LOC	50.00%
Total guarantees	$ 56.5
Asset retirement obligation activity
Balance at the beginning of the year	545	$ 262.3	$ 262.3
Closure Payments	(3.7)	(1)
Accretion expense	18.3	11.1
Balance at the end of the year	$ 559.6	$ 272.4	545	$ 262.3
Peru
ASSET RETIREMENT OBLIGATION:
Period after which successive reviews are required by the law (in years)	5 years
Number of units with future closure costs recognized as an asset retirement obligation | item	3
Asset retirement obligation activity
Changes in estimates				$ 28.1
Mexico
Asset retirement obligation activity
Changes in estimates			$ 269.3

BENEFIT PLANS_ (Details)

BENEFIT PLANS: (Details) $ in Millions	9 Months Ended
	Sep. 30, 2021USD ($)plan	Sep. 30, 2020USD ($)
Benefit plans
Number of noncontributory defined benefit pension plans | plan	2
Post retirement defined benefit plans and defined contribution plan
Defined benefit plan, net periodic benefit costs
Service cost	$ 1.1	$ 1
Interest cost	1.2	1.2
Expected return on plan assets	(2.6)	(2.1)
Amortization of prior service cost / (credit)	0.1	0.1
Amortization of net loss/(gain)	0.2	0.2
Net periodic benefit cost	0	0.4
Post-retirement Health care plans
Defined benefit plan, net periodic benefit costs
Interest cost	1.3	0.9
Amortization of net loss/(gain)	0.1
Net periodic benefit cost	$ 1.4	$ 0.9

COMMITMENTS AND CONTINGENCIES_2

COMMITMENTS AND CONTINGENCIES: - Environmental matters (Details) $ in Millions	9 Months Ended		12 Months Ended
	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Dec. 31, 2011personcategory
Environmental costs
Environmental capital investment	$ 60.6	$ 24.6
Peru
Environmental costs
Environmental capital investment	2.9	4
Mexico
Environmental costs
Environmental capital investment	$ 57.7	$ 28.6
Number of categories of collective actions | category			3
Minimum number of people claiming injury due to collective action initiative in Civil Federal Procedures Code (CFPC) | person			30

COMMITMENTS AND CONTINGENCIES_3

COMMITMENTS AND CONTINGENCIES: - Guaymas sulfuric acid spill (Details)	Jul. 09, 2019m³	Sep. 30, 2021itemm³
Climate change [Member]
Period of sustainability reports issued		10 years
Marine Terminal in Guaymas
Volume of sulfuric acid discharged in the incident at Guaymas	3
Water volume at Guaymas bay		340,000,000
Number of times of renewal | item		4
Number of years of each renewal		2 years

COMMITMENTS AND CONTINGENCIES_4

COMMITMENTS AND CONTINGENCIES: - Litigation matters (Details)	3 Months Ended	6 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2016lawsuit	Jun. 30, 2015lawsuititem	Sep. 30, 2021claimlawsuititem	Dec. 31, 2015itemlawsuit	Dec. 31, 2018item	Dec. 31, 2017lawsuit	Dec. 31, 2016item
Litigation Matter
Number of collective action lawsuits		6
Number of subsidiaries against which lawsuits were filed | item		2
Number of collective action lawsuits dismissed		3
Number of lawsuits in process			3
Number of civil actions seeking damages						33
Number Of Constitutional Action Lawsuits				4
Number of subsidiaries to which environmental impact authorizations were granted | item				1
Tia Maria
Litigation Matter
Number of lawsuits			5
Buenavista del Cobre, S.A. de C.V
Litigation Matter
Number of civil actions seeking damages | item				8	3		3
Number of resolutions | claim			45
Francisca Garcia Enriquez
Litigation Matter
Number of additional constitutional lawsuits filed				2
Mario Alberto Salcido et al; Maria Elena Heredia Bustamante et al; Martin Eligio Ortiz Gamez et al and Maria de los Angeles Enriquez Bacame et al
Litigation Matter
Number of additional constitutional lawsuits filed	4
Mario Alberto Salcido et al; Maria Elena Heredia Bustamante et al; Martin Eligio Ortiz Gamez et al and Maria de los Angeles Enriquez Bacame et al | Mexico
Litigation Matter
Number of monitoring wells downstream from the dam | item			3
Period to submit Semarnat			2 years
Norberto Bustamante et al
Litigation Matter
Number of additional constitutional lawsuits filed			2
Acciones Colectivas de Sinaloa
Litigation Matter
Number of lawsuits in process			2
Defensa Colectiva
Litigation Matter
Number of lawsuits in process			1

COMMITMENTS AND CONTINGENCIES_5

COMMITMENTS AND CONTINGENCIES: - Labor matters (Details)	Jul. 22, 2021PEN (S/)	Jul. 22, 2021USD ($)	Dec. 31, 2021	Sep. 30, 2021USD ($)item	Jun. 30, 2021PEN (S/)	Jun. 30, 2021USD ($)	Sep. 30, 2021USD ($)itememployee	Jul. 12, 2021item
Peru | Labor Matters
Labor matters
Percentage of labor unionized				70.40%			70.40%
Total number of workers | employee							4,645
Number of labor unions							6
Number of labor unions represent majority of workers							1
Number of labor unions other than majority workers unions							5
Term of agreement					4 years	4 years
Extended term of agreement	6 years	6 years
Annual salary increase (as a percent)			5.00%	5.00%
Labor expense	S/ 90,000	$ 21,760			S/ 60,000	$ 14,507
Number of labor unions of collective agreement signed								2
Long term agreement bonus	S/ 10,000	$ 2,418
Number of unions decided to forego advancing conversation				6			6
Mexico | San Martin
Labor matters
Budgeted cost for rehabilitation of mine | $				$ 90,100,000			$ 90,100,000

COMMITMENTS AND CONTINGENCIES_6

COMMITMENTS AND CONTINGENCIES: - Others (Details) S/ in Millions, $ in Millions	Feb. 20, 2020MW	Jul. 15, 2019complaint	Jun. 30, 2021USD ($)	Jun. 30, 2018USD ($)T	May 31, 2016MW	Jul. 31, 2014MW	Jun. 30, 2014MW	Sep. 30, 2021USD ($)itempersonT	Sep. 30, 2021PEN (S/)itempersonT
Other commitments:
Commitment for capital projects								$ 369.4
Tia Maria | Peru
Other commitments:
Project budget								1,400
Number Of Complaints | complaint		3
Amount spend as of the current date								$ 340.7
Annual production ( in tons) | T								120,000	120,000
Number of workers expected to be directly employed | item								600	600
Number of workers expected to be indirectly employed | item								4,200	4,200
Toquepala Concentrator Expansion | Peru
Other commitments:
Amount committed to funding for social and infrastructure improvement projects								$ 107.6	S/ 445.0
Commitment liability recorded in the balance sheet								32.5
Development Fund Moquegua Region | Peru
Other commitments:
Amount committed to funding for social and infrastructure improvement projects								$ 241.8	S/ 1,000.0
Number of schools agreed for construction. | item								3	3
Amount committed to funding for school projects								$ 3.8	S/ 15.9
Copper | Michiquillay | Peru
Other commitments:
Annual production ( in tons) | T				225,000
Contingent contractual obligation				$ 400
Estimated mineralized material (in tons) | T				1,150,000,000
Copper grade percentage				0.63%
Initial mine life				25 years
Contractual obligation paid on project			$ 12.5	$ 12.5
Remaining amount to pay if project is developed								$ 375
Educational Project | Tia Maria | Peru
Other commitments:
Number of jobs expected to be generated | person								9,000	9,000
Number of Direct Jobs Expected to be Generated | person								3,600	3,600
Number of Indirect Jobs Expected to be Generated | person								5,400	5,400
Educational Project | Toquepala Concentrator Expansion | Peru
Other commitments:
Amount committed to funding for social and infrastructure improvement projects								$ 4.2	S/ 17.2
Educational Project | Development Fund Moquegua Region | Peru
Other commitments:
Amount committed to funding for social and infrastructure improvement projects								26.2	108.4
Water Treatment | Development Fund Moquegua Region | Peru
Other commitments:
Amount committed to funding for social and infrastructure improvement projects								19.3	79.9
Amount committed for funding social and infrastructure improvement projects, build tracks and sidewalks								1.5	6.4
Social Investment For Taxes | Toquepala Concentrator Expansion | Peru
Other commitments:
Amount committed to funding for social and infrastructure improvement projects								16.7	69
Social Investment For Taxes | Development Fund Moquegua Region | Peru
Other commitments:
Amount committed to funding for social and infrastructure improvement projects								$ 21	S/ 86.7
Number of Infrastructure Projects Agreed for Construction | item								2	2
Electroperu S.A | Power purchase agreements | Peru
Other commitments:
Purchase agreement, contracted power capacity (in megawatts) | MW							120
Term of power purchase agreement related to sale of power plant							20 years
Parque Eolico de Fenicias, S. de R.L. de C.V | Power purchase agreements | Mexico
Other commitments:
Purchase agreement, contracted power capacity (in megawatts) | MW	611,400
Term of power purchase agreement related to sale of power plant	20 years
Kallpa | Power purchase agreements | Peru
Other commitments:
Purchase agreement, contracted power capacity (in megawatts) | MW						120
Term of power purchase agreement related to sale of power plant						10 years
Kallpa | Power purchase agreements | Peru | Maximum
Other commitments:
Purchase agreement, contracted power capacity (in megawatts) | MW					80

STOCKHOLDERS' EQUITY_ - Treasur

STOCKHOLDERS' EQUITY: - Treasury Stock (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Activity in treasury stock
Balance at the beginning of the period		$ 3,063.5
Balance at the end of the period	$ 3,048	$ 3,080.8	$ 3,048
Southern Copper common shares
Activity in treasury stock
Treasury stock balance at the end of the period (in shares)		111,514,817		111,522,817
TREASURY STOCK: | Southern Copper common shares
Activity in treasury stock
Balance at the beginning of the period		$ 2,767.5	2,767.9
Used for corporate purposes	(0.4)	(0.1)	(0.4)
Balance at the end of the period	2,767.5	2,767.4	2,767.5
TREASURY STOCK: | Parent Company common shares
Activity in treasury stock
Balance at the beginning of the period		296	281
Other activity, including dividend, interest and foreign currency transaction effect		17.4	(0.5)
Balance at the end of the period	$ 280.5	$ 313.4	$ 280.5
Treasury stock balance at the end of the period (in shares)		85,841,694		87,598,097

STOCKHOLDERS' EQUITY_ - Repurch

STOCKHOLDERS' EQUITY: - Repurchase Program (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2008
SCC share repurchase program:
Amount authorized for share repurchase program	$ 3,000	$ 500
Number of Shares Purchased	119.5
Maximum Number of Shares that May Yet Be Purchased Under the Plan @ $39.68	1.5
Cost of purchase of shares	$ 2,900
Closing price of NYSE (in dollars per share)	$ 56.14
Percentage of ownership by parent	88.90%

STOCKHOLDERS' EQUITY_ - Directo

STOCKHOLDERS' EQUITY: - Directors' Stock Award Plan (Details) - shares	Apr. 26, 2018	Sep. 30, 2021
Directors' Stock Award Plan
Share based Compensation Plan
Common shares received on election as director	1,200	1,600
Additional shares issued at each annual general meeting		1,600
Total SCC shares reserved for the plan		600,000
Period of extension of plan	5 years
Increased share awards issued to directors		1,600
New 2021 grant [Member]
Share based Compensation Plan
Numbers of shares shall be granted quarterly and conditioned upon the attendance of each director to each Board meeting		1,600

STOCKHOLDERS' EQUITY - Compensa

STOCKHOLDERS' EQUITY - Compensation Plan (Details) $ / shares in Units, $ in Millions	1 Months Ended				9 Months Ended
	Nov. 30, 2018$ / shares	Nov. 30, 2018$ / shares	Jan. 31, 2015$ / shares	Jan. 31, 2015$ / shares	Sep. 30, 2021USD ($)$ / sharesshares	Sep. 30, 2020USD ($)$ / sharesshares
Employee Stock Purchase 2015 Plan
Information related to compensation cost
Purchase price for initial subscription (in dollars per share) | (per share)			$ 38.44	$ 2.63
Percentage of title acquired by employee in every two years on shares paid in previous two years					50.00%
Period of plan					8 years
Ratio of bonus shares granted to participant					0.1
Stock based compensation expense | $					$ 0.5	$ 0.5
Unrecognized compensation expense | $					$ 1	$ 1.5
Stock award activity, Shares
Outstanding shares at the beginning of the period | shares					1,264,410	1,379,734
Exercised (in shares) | shares					(381,288)	(54,221)
Outstanding shares at the end of the period | shares					883,122	1,325,513
Unit Weighted Average Grant Date Fair Value
Outstanding shares at the beginning of the period (in dollars per share) | $ / shares					$ 2.63	$ 2.63
Exercised (in dollars per share) | $ / shares					2.63	2.63
Outstanding shares at the end of the period (in dollars per share) | $ / shares					$ 2.63	$ 2.63
Employee Stock Purchase 2018 Plan
Information related to compensation cost
Purchase price for initial subscription (in dollars per share) | (per share)	$ 37.89	$ 1.86
Percentage of title acquired by employee in every two years on shares paid in previous two years					50.00%
Period of plan					8 years
Ratio of bonus shares granted to participant					0.1
Stock based compensation expense | $					$ 0.5	$ 0.5
Unrecognized compensation expense | $					$ 3.3	$ 4
Stock award activity, Shares
Outstanding shares at the beginning of the period | shares					3,918,458	4,002,898
Exercised (in shares) | shares					(716,449)	(37,940)
Outstanding shares at the end of the period | shares					3,202,009	3,964,958
Unit Weighted Average Grant Date Fair Value
Outstanding shares at the beginning of the period (in dollars per share) | $ / shares					$ 1.86	$ 1.86
Exercised (in dollars per share) | $ / shares					1.86	1.86
Outstanding shares at the end of the period (in dollars per share) | $ / shares					$ 1.86	$ 1.86

STOCKHOLDERS' EQUITY_ - Non Con

STOCKHOLDERS' EQUITY: - Non Controlling Interest (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Non-controlling interest activity
Balance at the beginning of the period			$ 51.2	$ 47.9
Net earnings	$ 3.6	$ 2.1	10.6	4.9
Dividend paid			(4.4)	(2.8)
Balance at the end of the period	$ 57.4	$ 50	$ 57.4	$ 50

FAIR VALUE MEASUREMENT_ (Detail

FAIR VALUE MEASUREMENT: (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Liabilities:
Long-term debt, Carrying Value	$ 6,546.7	$ 6,544.2
Long-term debt, Fair Value	8,503	9,077.8
Short-term investment:
Trading securities	626.4	410.2
Available-for-sale debt securities:
Available-for-sale Securities, Current, Total	0.4	0.6
Quoted prices in active markets for identical assets (Level 1)
Liabilities:
Long-term debt, Carrying Value	6,195.8	6,193.6
Long-term debt, Fair Value	8,124.6	8,692.1
Significant other observable inputs (Level 2)
Liabilities:
Long-term debt, Carrying Value	350.9	350.6
Long-term debt, Fair Value	378.4	385.7
Fair value measurements recurring | Fair value as of the end of the period
Short-term investment:
Trading securities	626.4	410.2
Derivative:
Total assets, fair value	1,615.6	1,031.9
Fair value measurements recurring | Fair value as of the end of the period | Copper
Derivative:
Provisionally priced sales	707.1	491.9
Fair value measurements recurring | Fair value as of the end of the period | Molybdenum
Derivative:
Provisionally priced sales	281.7	129.2
Fair value measurements recurring | Asset backed securities | Fair value as of the end of the period
Available-for-sale debt securities:
Available-for-sale debt securities	0.2	0.3
Fair value measurements recurring | Mortgage backed securities | Fair value as of the end of the period
Available-for-sale debt securities:
Available-for-sale debt securities	0.2	0.3
Fair value measurements recurring | Quoted prices in active markets for identical assets (Level 1)
Short-term investment:
Trading securities	626.4	410.2
Derivative:
Total assets, fair value	1,615.2	1,031.3
Fair value measurements recurring | Quoted prices in active markets for identical assets (Level 1) | Copper
Derivative:
Provisionally priced sales	707.1	491.9
Fair value measurements recurring | Quoted prices in active markets for identical assets (Level 1) | Molybdenum
Derivative:
Provisionally priced sales	281.7	129.2
Fair value measurements recurring | Significant other observable inputs (Level 2)
Available-for-sale debt securities:
Available-for-sale Securities, Current, Total	0.4	0.6
Fair value measurements recurring | Significant other observable inputs (Level 2) | Asset backed securities
Available-for-sale debt securities:
Available-for-sale debt securities	0.2	0.3
Fair value measurements recurring | Significant other observable inputs (Level 2) | Mortgage backed securities
Available-for-sale debt securities:
Available-for-sale debt securities	$ 0.2	$ 0.3

REVENUE_ - Revenue by Geographi

REVENUE: - Revenue by Geographical Areas (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenue Recognition
Net sales	$ 2,680.9	$ 2,129.1	$ 8,110.4	$ 5,634.2
Corporate, other and eliminations
Revenue Recognition
Net sales	(42.8)	(29.7)	(107.9)	(78)
Mexican Open-pit | Operating segment
Revenue Recognition
Net sales	1,425.8	1,181.7	4,536.6	3,152.1
Mexican IMMSA Unit | Operating segment
Revenue Recognition
Net sales	175.1	140.9	460.8	377
Peruvian Operations | Operating segment
Revenue Recognition
Net sales	1,122.8	836.2	3,220.9	2,183.1
Mexico
Revenue Recognition
Net sales	560.5	374.3	1,620.1	1,066.5
Mexico | Corporate, other and eliminations
Revenue Recognition
Net sales	(42.8)	(29.7)	(107.9)	(78)
Mexico | Mexican Open-pit | Operating segment
Revenue Recognition
Net sales	483.1	319.5	1,431.7	890.3
Mexico | Mexican IMMSA Unit | Operating segment
Revenue Recognition
Net sales	115.7	84.5	291.8	254.2
Mexico | Peruvian Operations | Operating segment
Revenue Recognition
Net sales	4.5		4.5
United States
Revenue Recognition
Net sales	407.4	354.8	1,302.6	976.3
United States | Mexican Open-pit | Operating segment
Revenue Recognition
Net sales	324.9	309.9	1,107.5	866.8
United States | Mexican IMMSA Unit | Operating segment
Revenue Recognition
Net sales	11.2	11.3	42.9	15.5
United States | Peruvian Operations | Operating segment
Revenue Recognition
Net sales	71.3	33.6	152.2	94
Peru
Revenue Recognition
Net sales	147.9	99.9	438.6	218.6
Peru | Mexican IMMSA Unit | Operating segment
Revenue Recognition
Net sales	(0.4)	4.8	(0.3)	10.4
Peru | Peruvian Operations | Operating segment
Revenue Recognition
Net sales	148.3	95.1	438.9	208.2
Brazil
Revenue Recognition
Net sales	104.1	65.6	329.2	145.9
Brazil | Mexican IMMSA Unit | Operating segment
Revenue Recognition
Net sales	10.9	6.7	18.4	11.6
Brazil | Peruvian Operations | Operating segment
Revenue Recognition
Net sales	93.2	58.9	310.8	134.3
Chile
Revenue Recognition
Net sales	113.7	55.4	267.9	164.2
Chile | Mexican Open-pit | Operating segment
Revenue Recognition
Net sales	(0.1)		2.8	19.5
Chile | Peruvian Operations | Operating segment
Revenue Recognition
Net sales	113.8	55.4	265.1	144.7
Other American countries
Revenue Recognition
Net sales	12.7	18.6	34.2	29.4
Other American countries | Mexican Open-pit | Operating segment
Revenue Recognition
Net sales	10.9	16.9	28.9	25.9
Other American countries | Mexican IMMSA Unit | Operating segment
Revenue Recognition
Net sales		0.7	0.7	2.1
Other American countries | Peruvian Operations | Operating segment
Revenue Recognition
Net sales	1.8	1	4.6	1.4
Switzerland
Revenue Recognition
Net sales	423.9	446.6	1,257.8	1,100.4
Switzerland | Mexican Open-pit | Operating segment
Revenue Recognition
Net sales	276	274	888.7	682.6
Switzerland | Mexican IMMSA Unit | Operating segment
Revenue Recognition
Net sales	20.3	19.2	46	50.1
Switzerland | Peruvian Operations | Operating segment
Revenue Recognition
Net sales	127.6	153.4	323.1	367.7
Italy
Revenue Recognition
Net sales	66.8	62.2	250.9	185.4
Italy | Mexican Open-pit | Operating segment
Revenue Recognition
Net sales			0.2
Italy | Mexican IMMSA Unit | Operating segment
Revenue Recognition
Net sales	3.9	2	5.9	6.3
Italy | Peruvian Operations | Operating segment
Revenue Recognition
Net sales	62.9	60.2	244.8	179.1
Spain
Revenue Recognition
Net sales	127	62.5	363.6	127.3
Spain | Mexican Open-pit | Operating segment
Revenue Recognition
Net sales	106.6	62.5	299.8	127.3
Spain | Peruvian Operations | Operating segment
Revenue Recognition
Net sales	20.4		63.8
Other European Countries
Revenue Recognition
Net sales	172.1	136.6	553.3	342.6
Other European Countries | Mexican Open-pit | Operating segment
Revenue Recognition
Net sales	54.2	42.4	202.2	118.8
Other European Countries | Mexican IMMSA Unit | Operating segment
Revenue Recognition
Net sales	7	11	40.3	20.7
Other European Countries | Peruvian Operations | Operating segment
Revenue Recognition
Net sales	110.9	83.2	310.8	203.1
Singapore
Revenue Recognition
Net sales	285.9	192.7	765.3	622.6
Singapore | Mexican Open-pit | Operating segment
Revenue Recognition
Net sales	119.9	55.9	354.8	233.9
Singapore | Mexican IMMSA Unit | Operating segment
Revenue Recognition
Net sales	6.3	0.6	14.8	5.7
Singapore | Peruvian Operations | Operating segment
Revenue Recognition
Net sales	159.7	136.2	395.7	383
Japan
Revenue Recognition
Net sales	166.9	144.3	501.7	392.8
Japan | Mexican Open-pit | Operating segment
Revenue Recognition
Net sales	(0.8)	15.2	23.6	26.9
Japan | Peruvian Operations | Operating segment
Revenue Recognition
Net sales	167.7	129.1	478.1	365.9
Other Asian countries
Revenue Recognition
Net sales	92	115.6	425.2	262.2
Other Asian countries | Mexican Open-pit | Operating segment
Revenue Recognition
Net sales	51.1	85.4	196.4	160.1
Other Asian countries | Mexican IMMSA Unit | Operating segment
Revenue Recognition
Net sales	0.2	0.1	0.3	0.4
Other Asian countries | Peruvian Operations | Operating segment
Revenue Recognition
Net sales	$ 40.7	$ 30.1	$ 228.5	$ 101.7

REVENUE_ - Revenue by Segment (

REVENUE: - Revenue by Segment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenue Recognition
Net sales	$ 2,680.9	$ 2,129.1	$ 8,110.4	$ 5,634.2
Corporate, other and eliminations
Revenue Recognition
Net sales	(42.8)	(29.7)	(107.9)	(78)
Mexican Open-pit | Operating segment
Revenue Recognition
Net sales	1,425.8	1,181.7	4,536.6	3,152.1
Mexican IMMSA Unit | Operating segment
Revenue Recognition
Net sales	175.1	140.9	460.8	377
Peruvian Operations | Operating segment
Revenue Recognition
Net sales	1,122.8	836.2	3,220.9	2,183.1
Copper
Revenue Recognition
Net sales	2,110.4	1,749.9	6,576.1	4,585.4
Copper | Corporate, other and eliminations
Revenue Recognition
Net sales	(21.8)	(14.1)	(54.7)	(34.7)
Copper | Mexican Open-pit | Operating segment
Revenue Recognition
Net sales	1,195	1,022.1	3,858.2	2,687.8
Copper | Mexican IMMSA Unit | Operating segment
Revenue Recognition
Net sales	24.3	21.2	75.5	50.9
Copper | Peruvian Operations | Operating segment
Revenue Recognition
Net sales	912.9	720.7	2,697.1	1,881.4
Molybdenum
Revenue Recognition
Net sales	294.5	119.8	746.3	352.8
Molybdenum | Mexican Open-pit | Operating segment
Revenue Recognition
Net sales	146.6	58.2	387.3	188.3
Molybdenum | Peruvian Operations | Operating segment
Revenue Recognition
Net sales	147.9	61.6	359	164.5
Silver
Revenue Recognition
Net sales	104.2	133	363.4	320.4
Silver | Corporate, other and eliminations
Revenue Recognition
Net sales	(19)	(17.5)	(48.1)	(38.9)
Silver | Mexican Open-pit | Operating segment
Revenue Recognition
Net sales	52.4	67	193.1	170.6
Silver | Mexican IMMSA Unit | Operating segment
Revenue Recognition
Net sales	37.2	48.4	122.6	111.1
Silver | Peruvian Operations | Operating segment
Revenue Recognition
Net sales	33.6	35.1	95.8	77.6
Zinc
Revenue Recognition
Net sales	98.7	62.2	215.6	175.4
Zinc | Corporate, other and eliminations
Revenue Recognition
Net sales	0.1	4.6	0.5	1.3
Zinc | Mexican IMMSA Unit | Operating segment
Revenue Recognition
Net sales	98.6	57.6	215.1	174.1
Other
Revenue Recognition
Net sales	73.1	64.2	209	200.2
Other | Corporate, other and eliminations
Revenue Recognition
Net sales	(2.1)	(2.7)	(5.6)	(5.7)
Other | Mexican Open-pit | Operating segment
Revenue Recognition
Net sales	31.8	34.4	98	105.4
Other | Mexican IMMSA Unit | Operating segment
Revenue Recognition
Net sales	15	13.7	47.6	40.9
Other | Peruvian Operations | Operating segment
Revenue Recognition
Net sales	$ 28.4	$ 18.8	$ 69	$ 59.6

REVENUE_ - Receivables by repor

REVENUE: - Receivables by reporting segment (Details) $ in Millions	9 Months Ended
	Sep. 30, 2021USD ($)T	Dec. 31, 2020USD ($)
Opening and closing balances of receivables
Trade receivables	$ 1,493.4	$ 1,068.9
Related parties, current	34.6	23.3
Corporate, other and eliminations
Opening and closing balances of receivables
Related parties, current	$ 7.8	7.1
Copper concentrates
Long Term Contracts
Long term contracts | T	188,000
Copper cathodes
Long Term Contracts
Long term contracts | T	48,000
Molybdenum concentrates
Long Term Contracts
Long term contracts | T	41,414
Sulfuric acid
Long Term Contracts
Long term contracts | T	322,415
Mexican Open-pit | Operating segment
Opening and closing balances of receivables
Trade receivables	$ 658.8	566
Related parties, current	25.1	15.4
Mexican IMMSA Unit | Operating segment
Opening and closing balances of receivables
Trade receivables	57.1	57.8
Peruvian Operations | Operating segment
Opening and closing balances of receivables
Trade receivables	777.5	445.1
Related parties, current	$ 1.7	$ 0.8

REVENUE_ - Provisionally prices

REVENUE: - Provisionally prices sales (Details) lb in Millions, $ in Millions	9 Months Ended
	Sep. 30, 2021USD ($)lb$ / item
Copper
Provisionally priced sales:
Provisional price sales adjustment amounts included in accounts receivable and net sales | $	$ 30.7
Copper | October 2021 Through February 2022
Provisionally priced sales:
Sales volume (in million lbs.) | lb	174.1
Provisional price | $ / item	4.06
Molybdenum
Provisionally priced sales:
Provisional price sales adjustment amounts included in accounts receivable and net sales | $	$ 8.2
Molybdenum | October 2021 Through December 2021
Provisionally priced sales:
Sales volume (in million lbs.) | lb	15.3
Provisional price | $ / item	18.45

SEGMENT AND RELATED INFORMATI_3

SEGMENT AND RELATED INFORMATION: (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)segment	Sep. 30, 2020USD ($)	Dec. 31, 2020USD ($)
Financial information related to segments
Number of reportable segments | segment			3
Financial information relating to segments
Net sales	$ 2,680.9	$ 2,129.1	$ 8,110.4	$ 5,634.2
Cost of sales (exclusive of depreciation, amortization and depletion)	927.5	948.9	2,856.8	2,881.3
Selling, general and administrative	31.3	33.4	92.9	94
Depreciation, amortization and depletion	203.4	196	599.4	582.8
Exploration	10.9	6.9	26.7	21.8
Operating income	1,507.8	943.9	4,534.6	2,054.3
Interest, net	(87.4)	(86.4)	(262.6)	(263)
Other income (expense)	(1.9)	(14)	(7.8)	(22.4)
Income taxes	(548.6)	(338.5)	(1,703.8)	(784.7)
Equity earnings of affiliate	1.3	3.1	14.4	1
Non-controlling interest	(3.6)	(2.1)	(10.6)	(4.9)
Net income attributable to SCC	867.6	506	2,564.2	980.3
Capital investment	243.1	134.5	695.5	348.8
Property and mine development, net	9,476.1	9,144.7	9,476.1	9,144.7	$ 9,458.7
Total assets	18,110.3	16,248.4	18,110.3	16,248.4	$ 16,946.5
Intersegment sales
Financial information relating to segments
Net sales	(42.8)	(29.7)	(107.9)	(78)
Corporate, other and eliminations
Financial information relating to segments
Net sales	(42.8)	(29.7)	(107.9)	(78)
Cost of sales (exclusive of depreciation, amortization and depletion)	(48.4)	(28.2)	(122.5)	(88.2)
Selling, general and administrative	2.9	2.6	8.4	5.7
Depreciation, amortization and depletion	9.4	8.9	28.4	28.2
Exploration	5.9	2.8	11.2	7
Operating income	(12.6)	(15.8)	(33.4)	(30.7)
Capital investment	2.3	1.2	6.8	6.1
Property and mine development, net	656.5	369.8	656.5	369.8
Total assets	4,125.6	2,785.4	4,125.6	2,785.4
Reportable subsegments
Financial information relating to segments
Net sales	2,680.9	2,129.1	8,110.4	5,634.2
Mexican Open-pit | Operating segment
Financial information relating to segments
Net sales	1,425.8	1,181.7	4,536.6	3,152.1
Cost of sales (exclusive of depreciation, amortization and depletion)	433.4	491	1,441.6	1,482.4
Selling, general and administrative	17.4	19.1	49.7	55
Depreciation, amortization and depletion	97.8	91	289	276
Exploration	0.6	0.4	1.8	1.9
Operating income	876.6	580.2	2,754.5	1,336.8
Capital investment	114.6	76	389.6	179.7
Property and mine development, net	4,551.1	4,540.5	4,551.1	4,540.5
Total assets	8,200.6	7,551	8,200.6	7,551
Mexican Open-pit | Reportable subsegments | Operating segment
Financial information relating to segments
Net sales	1,425.8	1,181.7	4,536.6	3,152.1
Mexican IMMSA Unit | Operating segment
Financial information relating to segments
Net sales	175.1	140.9	460.8	377
Cost of sales (exclusive of depreciation, amortization and depletion)	135.8	91	328.8	285.1
Selling, general and administrative	2.9	2.6	7.8	6.8
Depreciation, amortization and depletion	12.7	10.7	39.4	31.6
Exploration	1.7	1.8	3.8	6.9
Operating income	22	34.8	81	46.6
Capital investment	29	16	61.5	55.7
Property and mine development, net	555.5	508.1	555.5	508.1
Total assets	1,009.9	879.7	1,009.9	879.7
Mexican IMMSA Unit | Intersegment sales
Financial information relating to segments
Net sales	42.8	29.7	107.9	78
Mexican IMMSA Unit | Reportable subsegments | Operating segment
Financial information relating to segments
Net sales	132.3	111.2	352.9	299
Peruvian Operations | Operating segment
Financial information relating to segments
Net sales	1,122.8	836.2	3,220.9	2,183.1
Cost of sales (exclusive of depreciation, amortization and depletion)	406.7	395.1	1,208.9	1,202
Selling, general and administrative	8.1	9.1	27	26.5
Depreciation, amortization and depletion	83.5	85.4	242.6	247
Exploration	2.7	1.9	9.9	6
Operating income	621.8	344.7	1,732.5	701.6
Capital investment	97.2	41.3	237.6	107.3
Property and mine development, net	3,713	3,726.3	3,713	3,726.3
Total assets	4,774.2	5,032.3	4,774.2	5,032.3
Peruvian Operations | Reportable subsegments | Operating segment
Financial information relating to segments
Net sales	$ 1,122.8	$ 836.2	$ 3,220.9	$ 2,183.1

SUBSEQUENT EVENTS_ (Details)

SUBSEQUENT EVENTS: (Details)	Nov. 23, 2021$ / shares
Subsequent Events
SUBSEQUENT EVENTS:
Quarterly dividend authorized (in dollars per share)	$ 1