Campbell Jones

Filed: 30 May 18, 5:00pm
                                                                      Exhibit 24

                                  POWER OF ATTORNEY

     Know all by these presents, that the undersigned hereby constitutes and
appoints Andrew D. Eich, Meghan E. DeMasi and Richard M. Solazzo or any of them,
with full power of substitution, as the undersigned's true and lawful attorneys-
in-fact and agents to:

     (1)    execute for and on behalf of the undersigned, in the undersigned's
            capacity as executive officer and/or director of Unimin Corporation,
            a Delaware corporation (as it may be subsequently renamed, the
            "Company"), Forms 3, 4 and 5 in accordance with Section 16(a) of the
            Securities Exchange Act of 1934, as amended (the "Exchange Act"),
            and the rules thereunder, and any other forms, reports or documents
            the undersigned may be required to file in connection with the
            undersigned's ownership, acquisition, or disposition of securities
            of the Company;

     (2)    do and perform any and all acts for and on behalf of the undersigned
            which may be necessary or desirable to complete and execute any such
            Form 3, 4 or 5, or other form, report or document, including without
            limitation, all forms or reports necessary to obtain EDGAR
            Identification Numbers, and timely file such form, report or
            document with the United States Securities and Exchange Commission
            and any stock exchange or similar authority; and

     (3)    take any other action of any type whatsoever in connection with the
            foregoing which, in the opinion of any such attorney-in-fact and
            agent, may be of benefit to, in the best interest of, or legally
            required by, the undersigned, it being understood that the documents
            executed by any such attorney-in-fact and agent on behalf of the
            undersigned pursuant to this Power of Attorney shall be in such form
            and shall contain such terms and conditions as such attorney-in-fact
            and agent may approve in his or her discretion.

     The undersigned hereby grants to each such attorney-in-fact and agent full
power and authority to do and perform any and every act and thing whatsoever
requisite, necessary, or proper to be done in the exercise of any of the rights
and powers herein granted, as fully to all intents and purposes as the
undersigned might or could do if personally present, with full power of
substitution or revocation, hereby ratifying and confirming all that any such
attorney-in-fact and agent, or such attorney-in-fact's and agent's substitute or
substitutes, shall lawfully do or cause to be done by virtue of this Power of
Attorney and the rights and powers herein granted.  The undersigned acknowledges
that the foregoing attorneys-in-fact and agents, in serving in such capacity at
the request of the undersigned, are not assuming any of the undersigned's
responsibilities to comply with Section 16 of the Exchange Act.

     This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4 and 5 with respect to the
undersigned's holdings of and transactions in securities issued by the Company,
unless earlier revoked by the undersigned in a signed writing delivered to the
foregoing attorneys-in-fact and agents.

                              [Signature Page Follows]

     IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of this 4th day of April, 2018.

                                        /s/ Campbell Jones
                                        Name: Campbell Jones