AMENDMENT NO. 5 TO LOAN AND SECURITY AGREEMENT

Exhibit 10.6

[Execution]

AMENDMENT NO. 5 TO LOAN AND SECURITY AGREEMENT

AMENDMENT NO. 5 TO LOAN AND SECURITY AGREEMENT, dated as of March 30, 2012 (this “Amendment No. 5”), by and among Wells Fargo Bank, National Association, successor by merger to Wachovia Bank, National Association, a national banking association, in its capacity as agent for the Lenders (as hereinafter defined) pursuant to the Loan Agreement as defined below (in such capacity, “Agent”), the parties to the Loan Agreement as lenders (individually, each a “Lender” and collectively, “Lenders”), U.S. Silica Company, a Delaware corporation (the “Company”), the subsidiaries of the Company from time to time party to the Loan Agreement as borrowers (each individually, together with the Company, a “Borrower” and collectively, “Borrowers”), USS Holdings, Inc., a Delaware corporation (“Parent”) and certain subsidiaries of Parent from time to time party to the Loan Agreement as Guarantors (individually, each a “Guarantor” and collectively, “Guarantors”).

WITNESSETH:

WHEREAS, Agent, Lenders, Borrowers and Guarantors have entered into financing arrangements pursuant to which Lenders (or Agent on behalf of Lenders) have made and may make loans and advances and provide other financial accommodations to Borrowers as set forth in the ABL Loan and Security Agreement, dated as of August 9, 2007, as amended by Amendment No. 1 and Consent to Loan and Security Agreement, dated as of November 25, 2008, by and among Agent, Lenders, Borrowers and Guarantors, Amendment No. 2 to Loan and Security Agreement and Consent, dated as of May 7, 2010, by and among Agent, Lenders, Borrowers and Guarantors and Amendment No. 3 to Loan and Security Agreement and Consent, dated as of June 8, 2011, by and among Agent, Lenders, Borrowers and Guarantors, Amendment No. 4 to Loan and Security Agreement dated as of January 22, 2012, by and among Agent, Lenders, Borrowers and Guarantors (as from time to time amended, modified, supplemented, extended, renewed, restated or replaced, the “Loan Agreement”, and together with all agreements, documents and instruments at any time executed and/or delivered in connection therewith or related thereto, as from time to time amended, modified, supplemented, extended, renewed, restated, or replaced, collectively, the “Financing Agreements”);

WHEREAS, Borrowers and Guarantors wish to amend certain provisions of the Loan Agreement as set forth herein, and Agent and Lenders are willing to agree to such amendments on the terms and subject to the conditions set forth herein; and

WHEREAS, by this Amendment No. 5, Agent, Lenders, Borrowers and Guarantors intend to evidence such amendments.

NOW, THEREFORE, in consideration of the foregoing and the mutual agreements and covenants contained herein, and other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto agree as follows:

1. Annual Audit. The phrase prior to the first“,” in Section 9.6(a)(i) is hereby amended and restated in its entirety as follows: “Within ninety (90) days after the end of each fiscal year (or, in the case of the fiscal year ending 2011,120 days) (or such earlier date if required by the Securities Exchange Commission)”.

2. Interpretation. For purposes of this Amendment No. 5, all terms used herein which are not otherwise defined herein, including but not limited to, those terms used in the recitals hereto, shall have the respective meanings assigned thereto in the Loan Agreement as amended by this Amendment No. 5.

3. Representations and Warranties. Each of the Loan Parties, jointly and severally, hereby represents and warrants with and to Agent and Lenders as follows, which representations and warranties shall survive the execution and delivery hereof, the truth and accuracy of, or compliance with each, together with the representations, warranties and covenants in the other Financing Agreements, being a continuing condition of the making of any Loans by Lenders (or Agent on behalf of Lenders) to Borrowers:

(a) after giving effect to this Amendment No. 5, no Default or Event of Default exists or has occurred and is continuing as of the date of this Amendment No. 5; and

(b) this Amendment No. 5 has been duly executed and delivered by the Loan Parties and the agreements and obligations of the Loan Parties contained herein constitute legal, valid and binding obligations of the Loan Parties enforceable against the Loan Parties in accordance with their respective terms.

4. Conditions Precedent. The amendments contained herein shall only be effective upon the satisfaction of each of the following conditions precedent in a manner satisfactory to Agent:

(a) Agent shall have received counterparts of this Amendment No. 5, duly authorized, executed and delivered by the Loan Parties and Required Lenders;

(b) after giving effect to this Amendment No. 5, no Default or Event of Default shall exist or have occurred and be continuing as of the date of this Amendment No. 5 or the Amendment No. 5 Effective Date.

5. Effect of Amendment No. 5. Except as expressly set forth herein, no other consents, amendments, changes or modifications to the Financing Agreements are intended or implied, and in all other respects the Financing Agreements are hereby specifically ratified, restated and confirmed by all parties hereto as of the effective date hereof and the Loan Parties shall not be entitled to any other or further amendment by virtue of the provisions of this Amendment No. 5 or with respect to the subject matter of this Amendment No. 5. To the extent of conflict between the terms of this Amendment No. 5 and the other Financing Agreements, the terms of this Amendment No. 5 shall control. The Loan Agreement and this Amendment No. 5 shall be read and construed as one agreement.

6. Governing Law. The validity, interpretation and enforcement of this Amendment No. 5 and any dispute arising out of the relationship between the parties hereto whether in contract, tort, equity or otherwise, shall be governed by the internal laws of the State of New York but excluding any principles of conflicts of law or other rule of law that would cause the application of the law of any jurisdiction other than the laws of the State of New York.

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7. Jury Trial Waiver. BORROWERS, GUARANTORS, AGENT AND LENDERS EACH HEREBY WAIVES ANY RIGHT TO TRIAL BY JURY OF ANY CLAIM, DEMAND, ACTION OR CAUSE OF ACTION ARISING UNDER THIS AMENDMENT NO. 5 OR ANY OF THE OTHER FINANCING AGREEMENTS OR IN ANY WAY CONNECTED WITH OR RELATED OR INCIDENTAL TO THE DEALINGS OF THE PARTIES HERETO IN RESPECT OF THIS AMENDMENT NO. 5 OR ANY OF THE OTHER FINANCING AGREEMENTS OR THE TRANSACTIONS RELATED HERETO OR THERETO IN EACH CASE WHETHER NOW EXISTING OR HEREAFTER ARISING, AND WHETHER IN CONTRACT, TORT, EQUITY OR OTHERWISE. BORROWERS, GUARANTORS, AGENT AND LENDERS EACH HEREBY AGREES AND CONSENTS THAT ANY SUCH CLAIM, DEMAND, ACTION OR CAUSE OF ACTION SHALL BE DECIDED BY COURT TRIAL WITHOUT A JURY AND THAT BORROWERS, GUARANTORS, AGENT OR ANY LENDER MAY FILE AN ORIGINAL COUNTERPART OF A COPY OF THIS AMENDMENT NO. 5 WITH ANY COURT AS WRITTEN EVIDENCE OF THE CONSENT OF THE PARTIES HERETO TO THE WAIVER OF THEIR RIGHT TO TRIAL BY JURY.

8. Binding Effect. This Amendment No. 5 shall be binding upon and inure to the benefit of each of the parties hereto and their respective successors and assigns.

9. Waiver, Modification, Etc. No provision or term of this Amendment No. 5 may be modified, altered, waived, discharged or terminated orally, but only by an instrument in writing executed by the party against whom such modification, alteration, waiver, discharge or termination is sought to be enforced.

10. Further Assurances. the Loan Parties shall execute and deliver such additional documents and take such additional action as may be reasonably requested by Agent to effectuate the provisions and purposes of this Amendment No. 5.

11. Entire Agreement. This Amendment No. 5 represents the entire agreement and understanding concerning the subject matter hereof among the parties hereto, and supersedes all other prior agreements, understandings, negotiations and discussions, representations, warranties, commitments, proposals, offers and contracts concerning the subject matter hereof, whether oral or written.

12. Headings. The headings listed herein are for convenience only and do not constitute matters to be construed in interpreting this Amendment No. 5.

13. Counterparts. This Amendment No. 5 may be executed in any number of counterparts, each of which shall be an original, but all of which taken together shall constitute one and the same agreement. Delivery of an executed counterpart of this Amendment No. 5 by telefacsimile or other electronic method of transmission shall have the same force and effect as delivery of an original executed counterpart of this Amendment No. 5. Any party delivering an executed counterpart of this Amendment No. 5 by telefacsimile or other electronic method of transmission shall also deliver an original executed counterpart of this Amendment No. 5, but the failure to do so shall not affect the validity, enforceability, and binding effect of this Amendment No. 5.

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IN WITNESS WHEREOF, the parties hereto have caused this Amendment No. 5 to be duly executed and delivered by their authorized officers as of the day and year first above written.

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