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                                                                      EXHIBIT 10


                               THIRD AMENDMENT TO
                AMENDED AND RESTATED LOAN AND SECURITY AGREEMENT

         This Third Amendment to Amended and Restated Loan and Security
Agreement (this "Third Amendment") dated as of April 26, 2001 by and among
United States Lime & Minerals, Inc., a Texas corporation ("U.S. Lime"), Texas
Lime Company, a Texas corporation ("TLC"), and Arkansas Lime Company, an
Arkansas corporation ("ALC," and together with U.S. Lime and TLC, collectively
referred to as the "Borrowers" and individually as a "Borrower"), and First
Union National Bank, a national banking association, as successor to CoreStates
Bank, N.A. ("Bank").

                                   BACKGROUND

         A. Borrowers and Bank are parties to an Amended and Restated Loan and
Security Agreement dated December 30, 1997, as amended by the First Amendment to
Amended and Restated Loan and Security Agreement, the Second Amendment to
Amended and Restated Loan and Security Agreement, and a letter agreement dated
as of April 21, 2000 (as the same has been amended and may hereafter amended,
restated, supplemented or otherwise modified and in effect from time to time,
the "Loan Agreement"), pursuant to which Bank continued and restated certain
credit facilities for the benefit of Borrowers under the terms and conditions
set forth therein. All initially capitalized terms used in this Third Amendment,
unless otherwise specifically defined herein, shall have the meanings ascribed
to them in the Loan Agreement.

         B. Bank and Borrowers desire to further amend the Loan Agreement to
increase the maximum amount, which may be outstanding under the Revolving Credit
at any one time, from $4,000,000 to $5,000,000, and to reduce the advance ratio
for Eligible Accounts from 90% to 80%, according to the terms hereof. Bank and
Borrowers have agreed to such modifications subject to the terms and conditions
hereof.

         NOW, THEREFORE, in consideration of the foregoing and of the mutual
covenants set forth herein, the parties hereto, intending to be legally bound
hereby, agree as follows:

         1. Ratification. This Third Amendment is a modification of the Loan
Agreement pursuant to Section 9.2 thereof. Except as expressly set forth herein,
or in any amendment to any of the documents referred to herein, Borrowers and
Bank acknowledge and agree that each and every term, condition and provision of
the Loan Agreement is hereby ratified and confirmed in full.

         2. Increase to Revolving Credit. On and after the date hereof, the
maximum principal amount of Cash Advances, which may be outstanding at any one
time under the Revolving Credit, shall be $5,000,000. The references to
"$4,000,000" in Sections 2.2.1(i), 2.4.13(i), 2.4.13(a), and 2.4.14 of the Loan
Agreement are hereby replaced with "$5,000,000."

         3. Borrowing Base Amended. The defined term "Borrowing Base" is hereby
amended and restated in its entirety as of the date hereof as follows:




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         "Borrowing Base" means the sum of (i) 80% of Borrowers' Eligible
         Accounts; plus (ii) the lesser of $1,000,000 and 50% of Eligible
         Inventory; less (a) the aggregate amount of all outstanding Cash
         Advances, and (b) the face amount of all issued and outstanding Letters
         of Credit.

         4. Revolving Credit Termination Date Extended. The defined term
"Revolving Credit Termination Date" is hereby amended and restated in its
entirety as of the date hereof as follows:

         "Revolving Credit Termination Date" means May 31, 2002, or such later
         date as Borrowers and Bank may agree in writing.

         5. Outstanding Indebtedness. Borrowers hereby unconditionally
acknowledge that, as of the date hereof, the outstanding principal balance under
the Revolving Credit is $825,000, and the aggregate face amount of outstanding
undrawn Letters of Credit is $175,000. Borrowers acknowledge and agree that the
foregoing balance of the Revolving Credit (including the amount of all draws
under outstanding Letters of Credit), together with interest, which shall accrue
from the date hereof at the rates set forth in the Loan Agreement, is owing to
Bank without claim, counterclaim, recoupment, defense or setoff of any kind.

         6. Revised Article 9 of the UCC. The parties acknowledge and agree to
the following provisions of this agreement in anticipation of the possible
application, in one or more jurisdictions to the transactions contemplated by
the Loan Agreement and hereby, of the revised Article 9 of the Uniform
Commercial Code in the form or substantially in the form approved by the
American Law Institute and the National Conference of Commissioners on Uniform
State Law and contained in the 2000 Official Text of the Uniform Commercial Code
("Revised Article 9").

                  6.1 Attachment. In applying the law of any jurisdiction in
which Revised Article 9 is in effect, the Collateral shall include, without
limitation, the following categories of assets as defined in Revised Article 9:
accounts and related supporting obligations; payment intangibles (to the extent
within the definition of Accounts under current Article 9 of the UCC);
inventory; as-extracted collateral consisting of extracted stone, limestone and
other minerals other than oil and gas (to the extent that such extracted stone,
limestone and other minerals would fall within the definition of inventory under
current Article 9 of the UCC); records; and any and all proceeds of any thereof,
wherever located, whether now owned or hereafter acquired.

                  6.2 Perfection by Filing. Bank may at any time and from time
to time, pursuant to the provisions of Section 3.1.2 of the Loan Agreement, file
financing statements, continuation statements and amendments thereto that
describe the Collateral as provided in Revised Article 9 and which contain any
other information required by Part 5 of Revised Article 9 for the sufficiency or
filing office acceptance of any financing statement, continuation statement or
amendment, including whether any Borrower is an organization, the type of
organization and any organization identification number issued to such Borrower.
Borrowers agree to furnish any such information to





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Bank promptly upon request. Any such financing statements, continuation
statements or amendments may be signed by Bank on behalf of Borrowers or any
Borrower, as provided in Section 3.1.2, and may be filed at any time in any
jurisdiction whether or not Revised Article 9 is then in effect in that
jurisdiction.

                  6.3 Other Perfection, etc. Borrowers shall at any time and
from time to time, whether Revised Article 9 is in effect in any particular
jurisdiction, take such steps as Bank may reasonably request for Bank (a) to
obtain an acknowledgement, in form and substance satisfactory to Bank, of any
bailee having possession of any of the Collateral that the bailee holds such
Collateral for Bank, and (b) otherwise to insure the continued perfection and
priority of Bank's security interest in any of the Collateral and of the
preservation of its rights therein, whether in anticipation and following the
effectiveness of Revised Article 9 in any jurisdiction.

                  6.4 Savings Clause. Nothing contained in this Section 6 shall
be construed to narrow the scope of Bank's security interest in any of the
Collateral or the perfection or priority thereof or to impair or otherwise limit
any of the rights, powers, privileges or remedies of Bank hereunder except (and
then only to the extent) mandated by Revised Article 9 to the extent then
applicable.

         7. Representations and Warranties. To induce Bank to enter into this
Third Amendment, Borrowers jointly and severally represent and warrant to Bank
as follows:

                  7.1 After giving effect to the modifications contained herein,
all representations, warranties and covenants made by Borrowers to Bank in the
Loan Agreement (except those relating to a specific date) are true and correct
in all material respects as of the date hereof, with the same force and effect
as though made as of the date hereof;

                  7.2 No Event of Default or Unmatured Event of Default has
occurred and is continuing under the Loan Agreement as of the date hereof;

                  7.3 Each Borrower is a corporation validly subsisting under
the laws of the state of its incorporation; the execution, delivery and
performance of this Third Amendment and any other documents and instruments
executed and delivered to Bank in connection herewith (i) are within each
Borrower's corporate powers, (ii) have been duly authorized by each Borrower's
Board of Directors, (iii) do not contravene any provision of law or any
indenture, agreement or undertaking to which any Borrower is a party or is
otherwise bound, any Borrower's Certificate of Incorporation, bylaws, or any
resolution of the Board of Directors of any Borrower, and (iv) require no
consent or approval of any governmental authority or any third party; and

                  7.4 This Third Amendment and any other documents and
instruments executed and delivered to Bank in connection herewith have been
validly executed and are enforceable against the Borrower or Borrowers party
thereto in accordance with their respective terms.




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Any failure of any of the representations and warranties made by Borrowers in
this Third Amendment to be true and correct in all material respects when made
shall constitute an Event of Default under the Loan Agreement.

         8. Conditions Precedent. The effectiveness of this Third Amendment, and
the performance by Bank of its obligations described herein, are subject to the
conditions precedent that Bank shall have received, in form and substance
satisfactory to Bank:

                  9.1 a completed and executed Ratio Certificate for the
Calendar Quarter ended March 31, 2001;

                  9.2 resolutions of the Boards of Directors of each Borrower
authorizing the execution, delivery and performance of this Third Amendment, the
Second Amended and Restated Note in the form attached hereto as Exhibit A (the
"Second Amended and Restated Note"), and the other documents and instruments
executed and delivered to Bank in connection herewith, certified by such
Borrower's Secretary that the same are true and complete copies of the originals
thereof and remain in full force and effect, not having been modified or
rescinded;

                  9.3 a completed and executed Borrowing Base Certificate for
the month ended March 31, 2001; and

                  9.4 an amendment fee payable to Bank equal to $10,000.

         10. Miscellaneous.

                  10.1 Entire Agreement. The Loan Agreement, as amended by this
Third Amendment, and the other Loan Documents, embody the entire agreement and
understanding between Bank and Borrowers. The Loan Agreement, together with this
Third Amendment, and all documents executed and delivered herewith, supersede
all prior agreements and understandings relating to subject matter hereof. This
Third Amendment together with the Loan Agreement, and the documents executed and
delivered in connection herewith and therewith shall be construed as one
agreement, and in the event of any inconsistency, the provisions of any
promissory note evidencing a portion of the Indebtedness shall control over the
provisions of this Third Amendment.

                  10.2 Counterparts. This Third Amendment may be executed in any
number of counterparts and by different parties on separate counterparts, each
of which counterparts, when so executed and delivered, shall be deemed to be an
original and all of which counterparts, taken together, shall constitute but one
and the same agreement. This Third Amendment shall be effective upon the
execution and delivery of a counterpart hereof by each of the parties hereto.

                  10.3 Captions. The captions or headings in this Third
Amendment are for convenience of reference only and in no way define, limit, or
describe the scope or intent of any provision of this Third Amendment.




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                  10.4 References to Note. All references to the term "Note" in
the Loan Agreement and the other Loan Documents shall mean and refer to the
Second Amended and Restated Note on and after the date hereof.

                  10.5 Successors and Assigns; Governing Law. This Third
Amendment shall be binding upon and inure to the benefit of the respective
parties hereto and their successors and assigns and shall be governed by, and
construed and enforced in accordance with, the internal laws of the Commonwealth
of Pennsylvania without regard to its principles of conflicts of laws.


                            [signature page follows]



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         IN WITNESS WHEREOF, the undersigned have executed this Third Amendment
as of the day and year first written above.



                                             
                                                BANK:


                                                       FIRST UNION NATIONAL BANK
                                                       (successor to CoreStates Bank, N.A.)


                                                       By:
                                                          -------------------------------------------
                                                                       Stuart MacGregor,
                                                                       Vice President

                                                BORROWERS:

                                                       UNITED STATES LIME & MINERALS, INC.
Attest:

By:                                                    By:
   ------------------------------                         -------------------------------------------
   Larry T. Ohms, Controller,                                   Timothy W. Byrne, President and
   Secretary, and Treasurer                                        Chief Executive Officer

                                                                TEXAS LIME COMPANY


By:                                                    By:
   ------------------------------                         -------------------------------------------
   Larry T. Ohms, Controller,                                   Timothy W. Byrne, President and
   Secretary and Treasurer

                                                                ARKANSAS LIME COMPANY


By:                                                    By:
   ------------------------------                         -------------------------------------------
   Larry T. Ohms, Controller,                                   Timothy W. Byrne, President and
   Secretary and Treasurer




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                                    Exhibit A

                                     Form of
                        Second Amended and Restated Note






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