Document:

Form of Letter Agreement

 EXHIBIT 10.21 
 [            ] 
 U.S. Silica Holdings,
Inc. 
 8490 Progress Drive, Suite 300 

Frederick, Maryland 21701 
  

	 	Re:	Advancement and Indemnification Rights 

In light of recent court decisions concerning the rights of corporate directors and officers (including directors designated by sponsor shareholder
investors) to advancement of expenses and indemnification, Golden Gate Private Equity, Inc. (“Golden Gate”) and U.S. Silica Holdings, Inc. (the “Company”) have agreed to enter into this Letter Agreement (this
“Agreement”) to clarify their understandings with respect to certain matters. Capitalized terms not defined elsewhere in this Agreement are used herein as defined in Section 3. 

This Agreement clarifies certain rights of (i) Golden Gate; (ii) any Golden Gate Affiliate or other persons or entities providing management,
advisory, consulting or other services at the direction or request of Golden Gate or any Golden Gate Affiliate to or for the benefit of the Company or any successors or direct or indirect parents or subsidiaries of the Company (individually,
including the Company, a “U.S. Silica Company,” and collectively, including the Company, the “U.S. Silica Companies”); (iii) any Fund; (iv) any persons designated by Golden Gate, any Golden Gate Affiliate
or any Fund to serve as a director, officer, board observer, partner, trustee, fiduciary, manager, employee, agent, consultant or advisor, or functional or foreign equivalent of the foregoing, of or to any of the U.S. Silica Companies or of or to
any partnership or joint venture of which any U.S. Silica Company is a partner or member (collectively, the “Golden Gate Designees”); and (v) any direct or indirect partners (including general partners), shareholders, members
(including managing members), affiliates, controlling persons, subsidiaries, directors, officers, fiduciaries, managers, employees and agents of any of the foregoing (those persons and entities identified in (i), (ii), (iii), (iv) and
(v) are herein referred to collectively as the “Indemnitees,” and individually as an “Indemnitee”), whether such right exists pursuant to any Organizational Document or any other agreement or document.

 The parties intend that (i) the U.S. Silica Companies are and shall at all times be the indemnitors of first resort with respect to any
and all matters for which advancement of expenses and indemnification are provided by the U.S. Silica Companies to or on behalf of any Indemnitee, without regard to the time of any related claims and liabilities or of any act, statement or omission
relating thereto, (ii) the U.S. Silica Companies shall advance expenses and/or indemnify each Indemnitee on a primary basis, and (iii) any Indemnitee may be required to seek advancement of expenses and/or indemnification from any other
potential source of such advancement or indemnification (including from any other Indemnitee) only if, and to the extent, that the U.S. Silica Companies are legally and/or financially unable to advance expenses to or on behalf of and/or indemnify,
as the case may be, such Indemnitee. 

 In consideration of the mutual agreements herein contained, and other good and valuable consideration -
including the agreement of the Golden Gate Designees to serve one or more U.S. Silica Companies (including without limitation on the board of directors or similar governing body thereof) - the receipt and sufficiency of which is hereby acknowledged,
all parties intending to be legally bound hereby agree as follows: 
 1. Company is Primary Indemnitor. 

Each of the undersigned U.S. Silica Companies hereby acknowledges and agrees that (a) each of the undersigned U.S. Silica Companies is an indemnitor
of first resort; (b) the obligations of the U.S. Silica Companies to each Indemnitee are primary, and any obligations of Golden Gate, any Golden Gate Affiliate or any Fund or other Indemnitee to provide advancement of expenses or
indemnification for any Losses incurred by Indemnitee and for which any U.S. Silica Company has agreed (or is otherwise obligated) to indemnify Indemnitee (whether under any Organizational Document or any other agreement or document) are secondary;
and (c) if Golden Gate, or any Golden Gate Affiliate, Fund or other Indemnitee, is obligated to pay, or pays, or causes to be paid for any reason, any expense or Loss which any U.S. Silica Company is otherwise obligated (whether under any
Organizational Document or other document or agreement) to pay to or on behalf of Indemnitee, then (x) Golden Gate, such Golden Gate Affiliate, Fund or other Indemnitee, as the case may be, shall be fully subrogated to and otherwise succeed to
all rights of Indemnitee with respect to such payment, including with respect to rights to claim such amounts from any of the U.S. Silica Companies; and (y) each of the undersigned U.S. Silica Companies shall jointly and severally reimburse,
indemnify and hold harmless (or cause one or more other U.S. Silica Companies to reimburse, indemnify and hold harmless) Golden Gate, such Golden Gate Affiliate, Fund or other Indemnitee, as the case may be, for all such payments actually made by
such entity or person on behalf of or for the benefit of Indemnitee. 
 2. Specific Waiver of Subrogation, Contribution, etc. 

To the fullest extent not prohibited by applicable law, each of the undersigned U.S. Silica Companies hereby unconditionally and irrevocably waives,
relinquishes and releases (and covenants and agrees not to exercise, and to cause each affiliate of any U.S. Silica Company not to exercise), any claims or rights that any U.S. Silica Company may now have or hereafter acquire against any Indemnitee
(in any capacity) that arise from or relate to the existence, payment, performance or enforcement of one of the U.S. Silica Companies’ obligations under this Agreement or under any indemnification obligation (whether pursuant to any other
contract, any Organizational Document or otherwise), including any right of subrogation, reimbursement, exoneration, contribution or indemnification and any right to participate in any claim or remedy of any Indemnitee against any other Indemnitee,
whether such claim, remedy or right arises in equity or under contract, statute, common law or otherwise, including any right to claim, take or receive from any Indemnitee, directly or indirectly, in cash or other property or by set-off or in any
other manner, any payment or security or other credit support on account of such claim, remedy or right. 

  
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 3. Definitions. As used in this Agreement, the phrase “including” shall not be deemed to be
a term of limitation but rather shall be construed to mean “including, without limitation” and the following terms are used with the meaning set forth herein: 
  

	 	(a)	“Golden Gate Affiliate” means any entity that, directly or indirectly, (i) is controlled by, (ii) controls or (iii) is under common
control with, Golden Gate; provided, that, under no circumstances shall any portfolio company of Golden Gate (including any U.S. Silica Company) be deemed a Golden Gate Affiliate hereunder. 

 

	 	(b)	“Fund” means any investment fund formed or managed by Golden Gate or any Golden Gate Affiliate or for which any Golden Gate Affiliate serves as an
investment adviser, and any other partnership, limited liability company or other legal entity that is a Golden Gate Affiliate which, directly or indirectly, owns equity securities of the Company or any other U.S. Silica Company.

  

	 	(c)	“Losses” means any and all damages, judgments, liabilities, assessments, fines, penalties, amounts paid in settlement, fees and costs (including
reasonable attorneys fees and costs) or other losses. 

  

	 	(d)	“Organizational Document” means an entity’s certificate of incorporation, bylaws, partnership agreement, limited liability company agreement,
operating agreement, indemnification agreement, or other similar or equivalent agreement or document. 

 4. Miscellaneous.

  

	 	(a)	This Agreement may be amended, modified, extended or terminated as to any U.S. Silica Company (and the provisions hereof may be waived) only by a written agreement
specifically identified as such and signed by Golden Gate and the relevant U.S. Silica Company. No oral amendment, modification or waiver of this Agreement shall be effective. 

 

	 	(b)	An Indemnitee’s rights under this Agreement and any Organizational Document or other agreement or document that gives rise to indemnification and/or advancement
rights are present contractual rights that shall fully vest upon any Indemnitee’s first service as a director, officer, board observer, fiduciary, partner, trustee, manager, employee, agent or functional or foreign equivalent of any of the
foregoing of any of the U.S. Silica Companies. No amendment, alteration or repeal of this Agreement, any Organizational Document or any other such agreement or document or of any provision hereof or thereof validly effected shall limit or restrict
any right of Indemnitee under this Agreement, any Organizational Document or such agreement or document in respect of any act, omission or statement of such Indemnitee occurring prior to such amendment, alteration or repeal.

  
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	 	(c)	Nothing in this Agreement shall be construed to require: (i) Golden Gate, any Golden Gate Affiliate or any other person or entity to provide management, advisory,
consulting or other services, or (ii) any Golden Gate Designee to serve as a director, officer or agent of any U.S. Silica Company (or in any other capacity). No Indemnitee’s rights hereunder shall be limited or impaired in any way if such
Indemnitee ceases, for any reason, to serve or provide services to any U.S. Silica Company. 

  

	 	(d)	To the extent permitted by applicable choice-of-law principles, this Agreement and all claims arising out of or based upon this Agreement or relating to the subject
matter hereof shall be governed by and construed in accordance with the domestic substantive laws of the State of Delaware without giving effect to any choice- or conflict-of-law principles or rules that would result in the application of the
domestic substantive law of any other jurisdiction. 

  

	 	(e)	Except as, and to the extent, expressly provided herein, (i) no right or remedy herein conferred is intended to be exclusive of any other right or remedy, and
every other right and remedy shall be cumulative and in addition to every other right and remedy given hereunder or now or hereafter existing at law or in equity or otherwise, so long as such right or remedy does not conflict with any right or
remedy provided hereunder, (ii) any and all rights to advancement of expenses and/or indemnification to which each Indemnitee has ever been, is or may in the future be entitled from the U.S. Silica Companies shall remain unchanged by this
Agreement, and (iii) the assertion or employment of any right or remedy hereunder, or otherwise, shall not prevent the concurrent assertion or employment of any other right or remedy. To the fullest extent permitted by applicable law, to the
extent that any term or condition of this Agreement conflicts with any term or condition under any other agreement or document to which any U.S. Silica Company or Indemnitee is a party or by which any of them are otherwise bound (whether pursuant to
an Organizational Document or any other agreement or document) with respect to the subject matter of this Agreement, the terms and conditions of this Agreement shall control. To the fullest extent permitted by applicable law, each U.S. Silica
Company hereby waives the right to enforce any rights under such other agreement to the extent that such rights or remedies conflict with any rights, remedies or other provisions hereunder. 

 

	 	(f)	Each Indemnitee that is not a direct party hereunder is and shall be considered an express and intended third-party beneficiary hereunder and shall be entitled to
enforce this Agreement to the same extent as a party hereunder. 

  

	 	(g)	 If any provision or provisions of this Agreement shall be held to be invalid, illegal or unenforceable for any reason whatsoever: (i) the
validity, legality and enforceability of the remaining provisions of this 

  
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Agreement (including each portion of any section or subsection of this Agreement containing any such provision held to be invalid, illegal or unenforceable, that is not itself invalid, illegal or
unenforceable) shall not in any way be affected or impaired thereby; (ii) such provision or provisions shall be deemed reformed to the extent necessary to conform to applicable law and to give the maximum effect to the intent of the parties
expressed herein; and (iii) to the fullest extent possible, the provisions of this Agreement (including each portion of any section or subsection of this Agreement containing any such provision held to be invalid, illegal or unenforceable, that
is not itself invalid, illegal or unenforceable) shall be construed so as to give effect to the intent manifested thereby. 

  

	 	(h)	This Agreement may be executed in any number of counterparts and by each of the parties in separate counterparts (any of which may be delivered by facsimile or pdf),
each of which when so executed will be deemed to be an original and all of which together will constitute one and the same instrument. 

 [THE REMAINDER OF THIS PAGE IS INTENTIONALLY LEFT BLANK.] 

  
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	 Very truly yours,
  

GOLDEN GATE PRIVATE EQUITY, INC.

		
	By:	 	 
	Name:
	Title:

 ACKNOWLEDGED AND AGREED TO as of the date of this letter. 

 

			
	 U.S. SILICA COMPANIES
  

U.S. Silica Holdings, Inc.

		
	By:	 	 
	Name:
	Title:

  

			
	GGC RCS Holdings, Inc.
		
	By:	 	 
	Name:
	Title:

  

			
	Coated Sand Solutions, LLC
		
	By:	 	 
	Name:
	Title:

  

			
	Preferred Rocks USS Inc.
		
	By:	 	 
	Name:
	Title:

  

			
	Hourglass Acquisition I, LLC
		
	By:	 	 
	Name:
	Title:

 SIGNATURE PAGE TO INDEMNITY
PRIORITY AGREEMENT 

			
	Hourglass Holdings, LLC
		
	By:	 	 
	Name:	 	
	Title:	 	

  

			
	USS Holdings, Inc.
		
	By:	 	 
	 Name:
	 	
	 Title:
	 	

  

			
	U.S. Silica Company
		
	By:	 	 
	 Name:
	 	
	 Title:
	 	

 SIGNATURE PAGE TO INDEMNITY
PRIORITY AGREEMENTForm of Corporate Governance and Director Designation Agreement

 EXHIBIT 10.22 
 DIRECTOR DESIGNATION AGREEMENT 
 THIS DIRECTOR DESIGNATION AGREEMENT (this
“Agreement”) is made and entered into as of                  , 201    , by and among GGC USS Holdings, LLC, a Delaware limited
liability company (the “Stockholder”) and U.S. Silica Holdings, Inc., a Delaware corporation (the “Company”). Unless otherwise indicated herein, capitalized terms used herein are defined in Section 4
hereof. 
 WHEREAS, as of the date hereof, the Company will effectuate an initial public offering of shares of the
Company’s common stock, par value $0.01 per share (the “Common Stock”), pursuant to a registration statement filed with the Securities and Exchange Commission (the “Initial Public Offering”); and 

WHEREAS, the parties hereto desire to enter into this Agreement to set forth certain rights and obligations of the Stockholder with
respect to the Company. 
 NOW, THEREFORE, the parties to this Agreement agree as follows: 

1. Voting Agreement; Board Nomination Rights. 
 (a) From and after the date hereof and until the provisions of this Section 1 cease to be effective and subject to the terms and conditions of this Agreement, the Stockholder (or its indirect
beneficial owners) shall have the right to nominate persons for election to the Board (each a “Nominee”) as follows: 
 (i) (x) prior to the earlier of (A) one year after the Stockholder’s Ownership Percentage becomes less than 50% or (B) the Stockholder’s Ownership Percentage becomes less than 35%,
such number of individuals as are collectively designated by the Stockholder, so long as the Company is able to comply with the requirement of Section 303A.01 of the New York Stock Exchange Listed Company Manual (the “Majority
Independent Director Requirement”) or the Majority Independent Director Requirement does not apply to the Company or (y) after the earlier of (A) or (B) in clause (x) hereof, but while the Stockholder’s Ownership Percentage is at
least 10%, such number of individuals in relative proportion to the Stockholder’s Ownership Percentage (rounded up), so long as the Company is able to comply with the Majority Independent Director Requirement or the Majority Independent
Director Requirement does not apply to the Company; and 
 (ii) subject to the provisions of this Section 1, during
such time as the Stockholder’s Ownership Percentage is at least 35%, the size (i.e., number of Board seats) shall not be more than [            
(        )]. 

 (b) The Company shall pay the reasonable out-of-pocket expenses incurred by each director in
connection with attending the meetings of the Board and any committee thereof. 
 (c) Notwithstanding anything to the contrary
contained herein, at such time as the Stockholder’s Ownership Percentage is less than 10%, the rights of the Stockholder under this Section 1 to nominate any Nominee shall terminate automatically and cease to have any further force
or effect. 
 (d) At every meeting of the Board, or a committee thereof, for which directors are nominated to stand for election
by stockholders of the Company, each Stockholder will have the right to select those persons to be nominated for election to the Board for each Retiring Director that was a prior Nominee of such Stockholder in accordance with this
Section 1. 
 (e) If a vacancy occurs because of the death, disability, disqualification, resignation or removal of
a Nominee (including by virtue of a removal of a Nominee at the discretion of the Stockholder), the Stockholder shall be entitled to nominate such person’s successors in accordance with this Agreement and the Board, subject to a determination
of the Board in good faith, after consultation with outside legal counsel that such action would not constitute a breach of applicable law, shall fill the vacancy with such successor Nominee. 

(f) If a Nominee is not nominated or elected to the Board because of the Nominee’s death, disability, disqualification, withdrawal
as a nominee or for other reason is unavailable or unable to serve on the Board, the Stockholder who nominated such person shall be entitled to nominate promptly another Nominee and the director position for which such Nominee was nominated shall
not be filled pending such nomination. 
 2. Company Obligations. 

(a) The Company agrees to use its commercially reasonable efforts to assure that (i) each Nominee is included in the Board’s
slate of nominees to the stockholders for each election of directors, and (ii) each Nominee is included in the proxy statement prepared by management of the Company in connection with soliciting proxies for every meeting of the stockholders of
the Company called with respect to the election of members of the Board, and at every adjournment or postponement thereof, and on every action or approval by written consent of the stockholders of the Company or the Board with respect to the
election of members of the Board. 
 (b) Notwithstanding anything herein to the contrary, the Company shall not be obligated to
cause to be nominated for election to the Board or recommend to the stockholders the election of any Nominee (i) who fails to submit to the Company on a timely basis such questionnaires as the Company may reasonably require of its directors
generally and such other information as the Company may reasonably request in connection with the preparation of its filings under the Securities Laws, or (ii) the Board or the Nominating Committee determines in good faith, after consultation
with outside legal counsel, that such action would constitute a breach of applicable law; provided, however, that upon the occurrence of either (i) or (ii) above, the Company shall promptly notify the applicable Stockholder
of the occurrence of such event and permit the applicable Stockholder to provide an alternate Nominee sufficiently in advance of 

  
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any Board action, meeting of the stockholders called or written action of stockholders with respect to such election of Nominees and the Company shall use commercially reasonable efforts to
perform its obligations under Section 2(a) with respect to such alternate Nominee (provided that if the Company provides at least 45 days advance notice of the occurrence of any such event such alternative Nominee must be
designated by the applicable Stockholder not less than 30 days in advance of any Board action, notice of meeting of the stockholders or written action of stockholders with respect to such election of Nominees). The Company shall use commercially
reasonable efforts to perform its obligations under Section 2(a) with respect to such alternate Nominee, provided that in no event shall the Company be obligated to postpone, reschedule or delay any scheduled meeting of the
stockholders with respect to such election of Nominees. 
 (c) At any time a vacancy occurs because of the death, disability,
resignation or removal of a Nominee, then the Board, or any committee thereof, shall not fill such vacancy until the earliest to occur of (i) such Stockholder has nominated a successor Nominee and the Board has filled the vacancy and appointed
such successor Nominee, (ii) such Stockholder fails to nominate a successor Nominee within 30 Business Days after receiving notification of the vacancy from the Company, and (iii) such Stockholder has specifically waived its right under
this Section 2(c). 
 (d) At any time that any Stockholder shall have any nomination rights under
Section 1, the Company shall not take any action, including making or recommending any amendment to the Certificate of Incorporation or the Company’s bylaws, (i) to reduce the size of the Board from
             (        ) if such decrease would cause the Company to fail to satisfy the Majority Independent Director Requirement without the
resignation of a Nominee or (ii) that otherwise could reasonably be expected to adversely affect the Stockholder’s rights under this Agreement, in each case without the prior written consent of the Stockholder. 

3. Definitions. 
 “Affiliate” means, with respect to any Person, any other Person which directly or indirectly controls, is controlled by or is under common control with such Person. For purposes of this
definition, “control” (including, with correlative meanings, the terms “controlled by” and “under common control with”), as applied to any Person, means the possession, directly or indirectly, of
the power to vote a majority of the securities having voting power for the election of directors (or other Persons acting in similar capacities) of such Person or otherwise to direct or cause the direction of the management and policies of such
Person through the ownership of voting securities, by contract or otherwise. For purposes of this Agreement, no Stockholder shall by reason of this Agreement be deemed to be an Affiliate of any other Stockholder or of the Company. 

“Board” means the board of directors of the Company. 

“Business Day” means a day, other than Saturday, Sunday or other day on which commercial banks in New York, New York are
authorized or required by law to close. 
 “Certificate of Incorporation” means the Company’s Certificate
of Incorporation as the same may be amended from time to time. 

  
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 “Nominating Committee” means the Corporate Governance and Nominating
Committee of the Board. 
 “Person” means an individual, corporation, partnership, association, trust, limited
liability company, joint venture, unincorporated organization or any other entity or organization, including a government or political subdivision or an agency or instrumentality thereof. 

“Retiring Director” means any director whose term expires at the next annual meeting of the stockholders of the Company
pursuant to the terms of the Company’s Certificate of Incorporation. 
 “Securities Act” means the
Securities Act of 1933, as amended. 
 “Securities Laws” means the Securities Act and the Securities Exchange
Act of 1934, as amended, and the rules promulgated thereunder. 
 “Stockholder’s Ownership Percentage”
means, at any time, the fraction (expressed as a percentage) that results from dividing (i) the number of shares of Common Stock owned by the Stockholder and its Affiliates at such time by (ii) the number of shares of Common Stock issued
and outstanding at such time. 
 “Subsidiary” means, at any time, with respect to any Person, any entity of
which securities or other ownership interests having ordinary voting power to elect a majority of the board of directors or other persons performing similar functions are at the time owned or controlled directly or indirectly by such Person.

 “Transfer” means, with respect to any Common Stock, to sell, assign, dispose of, exchange, or otherwise
directly transfer such Common Stock or agree or commit to do any of the foregoing, except for any Transfers to an Affiliate not otherwise prohibited hereby. 
 4. Amendment and Waiver. Any provision of this Agreement may be amended or waived if, but only if, such amendment or waiver is in writing and is signed, in the case of an amendment, by each party
to this Agreement, or in the case of a waiver, by the party against whom the waiver is to be effective. No failure or delay by any party in exercising any right, power or privilege hereunder shall operate as a waiver thereof nor shall any single or
partial exercise thereof preclude any other or further exercise thereof or the exercise of any other right, power or privilege. The rights and remedies herein provided shall be cumulative and not exclusive of any rights or remedies provided by law.

 5. Benefit of Parties. This Agreement shall be binding upon and shall inure to the benefit of the parties hereto and
their respective successors and assigns. Except as otherwise expressly provided herein, nothing herein contained shall confer or is intended to confer on any third party or entity that is not a party to this Agreement any rights under this
Agreement. 
 6. Headings. Headings are for ease of reference only and shall not form a part of this Agreement.

  
 4 

 7. Governing Law. This Agreement shall be construed in accordance with and governed
by the law of the State of Delaware without giving effect to the principles of conflicts of laws thereof. 
 8.
Jurisdiction. Any suit, action or proceeding seeking to enforce any provision of, or based on any matter arising out of or in connection with, this Agreement may be brought against any of the parties in any federal court located in the State
of Delaware or any Delaware state court, and each of the parties hereby consents to the exclusive jurisdiction of such court (and of the appropriate appellate courts) in any such suit, action or proceeding and waives any objection to venue laid
therein. Process in any such suit, action or proceeding may be served on any party anywhere in the world, whether within or without the jurisdiction of any such court. Without limiting the foregoing, the parties agree that service of process upon
such party at the address referred to in Section 15, together with written notice of such service to such party, shall be deemed effective service of process upon such party. 

9. WAIVER OF JURY TRIAL. EACH OF THE PARTIES HERETO HEREBY IRREVOCABLY WAIVES ANY AND ALL RIGHT TO TRIAL BY JURY IN ANY LEGAL
PROCEEDING ARISING OUT OF OR RELATED TO THIS AGREEMENT OR THE TRANSACTIONS CONTEMPLATED HEREBY. 
 10. Entire Agreement.
This Agreement (including the Schedules constituting a part of this Agreement) and any other writing signed by authorized representatives of each of the parties after the date hereof that specifically references this Agreement, constitute the entire
agreement among the parties with respect to the subject matter hereof and supersede all prior agreements, understandings and negotiations, both written and oral between the parties with respect to the subject matter hereof. 

11. Counterparts; Effectiveness. This Agreement may be signed in any number of counterparts, each of which shall be deemed an
original. This Agreement shall become effective when each party shall have received a counterpart hereof signed by each of the other parties. An executed copy or counterpart hereof delivered by facsimile shall be deemed an original instrument.

 12. Severability. If any provision of this Agreement or the application thereof to any Person or circumstance shall be
invalid or unenforceable to any extent, the remainder of this Agreement and the application of such provisions to other Persons or circumstances shall not be affected thereby and shall be enforced to the greatest extent permitted by law. 

13. Further Assurances. The Stockholders shall execute and deliver such further instruments and do such further acts and things as
may be required to carry out the intent and purpose of this Agreement. 
 14. Specific Performance. The parties
hereto agree that irreparable damage would occur if any provision of this Agreement were not performed in accordance with the terms hereof and that the parties shall be entitled to an injunction or injunctions to prevent breaches of this Agreement
or to enforce specifically the performance of the terms and provisions hereof in any federal or state court located in the State of Delaware, in addition to any other remedy to which they are entitled at law or in equity. 

  
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 15. Notices. All notices, requests and other communications to any party or to the
Company shall be in writing (including telecopy or similar writing) and shall be given, 
 If to the Company: 

U.S. Silica Holdings, Inc. 
 8490 Progress Drive, Suite 300 
 Frederick, MD 21701 

Attention: Chief Executive Officer 
 Facsimile: (            )
            -             
 With a copy to (which shall not constitute notice): 
 Kirkland &
Ellis LLP 
 555 California Street, #2700 
 San Francisco, CA 94104 
 Attention: Stephen D. Oetgen 

Facsimile: (415) 439-1500 
 If to the Stockholder: 
 c/o Golden Gate Private Equity, Inc. 

One Embarcadero Center, 39th Floor 
 San Francisco, CA 94111 
 Attention: Prescott Ashe 

Facsimile: (415) 983-2701 
 With a copy to (which shall not constitute notice): 
 Kirkland &
Ellis LLP 
 555 California Street, #2700 
 San Francisco, CA 94104 
 Attention: Stephen D. Oetgen 

Facsimile: (415) 439-1500 

or to such other address or telecopier number as such party or the Company may hereafter specify for the purpose by notice to the other parties and the
Company. Each such notice, request or other communication shall be effective when delivered at the address specified in this Section 15 during regular business hours. 

16. Distributions. In the event the Stockholder distributes any Common Stock to any of the direct or indirect members or partners
of the Stockholder (each such person receiving Common Stock thereby, a “Qualified Third-Party Beneficiary”), the Stockholder may, in its sole and absolute discretion, elect to assign to such Qualified Third-Party Beneficiary, in whole or
in part, its rights hereunder with respect to the Stockholder distributed to such Qualified Third-Party Beneficiary. In such event, with respect to the Common Stock distributed to such Qualified Third-Party Beneficiary, such Qualified Third-Party
Beneficiary shall succeed to all of the rights and obligations of the Stockholder under this Agreement. 
 17.
Enforcement. The parties hereto covenant and agree that the disinterested members of the Board or the disinterested members of any Board committee so designated by the Board have the right to enforce, waive or take any other action with
respect to this Agreement, the Termination Agreement between the Company 

  
 6 

 
and GGC Administration, LLC and the Registration Agreement among the Company and certain of its stockholders. 
 *        *        *        *        *

  
 7 

 IN WITNESS WHEREOF, the parties hereto have executed this Stockholders Agreement on the day
and year first above-written. 
  

			
	U.S. SILICA HOLDINGS, INC.
		
	By:	 	  

	Name:	 	
	Title:	 	
	
	GGC USS HOLDINGS, LLC
		
	By:	 	  

	Name:	 	
	Title:	 	

  
 [Signature Page to
Director Designation Agreement]

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