Exhibit 3.15.1

                           CERTIFICATE OF AMENDMENT
                                      OF
                         CERTIFICATE OF INCORPORATION

     Morgan National Silica Co., a corporation organized and existing under and
by virtue of the General Corporation Law of the State of Delaware,

DOES HEREBY CERTIFY:

     FIRST:  That the Board of Directors, of said corporation, by unanimous
written consent, adopted a resolution proposing and declaring advisable the
following amendment to the Certificate of Incorporation of said corporation:

          RESOLVED, that the Certificate of Incorporation of MORGAN
     NATIONAL SILICA CO. be amended by changing Article First thereof
     to read as follows:

             "FIRST:  The name of the corporation is PENNSYLVANIA
        GLASS SAND CORPORATION (hereinafter called the "Corporation")."

     SECOND:  That in lieu of a meeting and vote of stockholders, the
stockholders have given unanimous written consent to said amendment in
accordance with the provisions of section 228 of the General Corporation Law of
the State of Delaware.

     THIRD:  That the aforesaid amendment was duly adopted in accordance with
the applicable provisions of sections 242 and 228 of the General Corporation Law
of the State of Delaware.

     FOURTH:  That this Certificate of Amendment of the Certificate of
Incorporation shall be effective on December 31, 1986.


     IN WITNESS WHEREOF, said Morgan National Silica Co. has caused this
certificate to be signed by Richard E. Goodell, its President, and attested by
Charles V. Bush, its Secretary, this   2nd    day of December, 1986.
                                     --------

                                        MORGAN NATIONAL SILICA CO.

(Corporate Seal)

                                        By /s/ Richard E. Goodell
                                           --------------------------------
                                                      President

ATTEST:

By /s/ Charles V. Bush
   --------------------------
          Secretary

                                       2


STATE OF WEST VIRGINIA )
                       : ss.:
COUNTY OF MORGAN       )

     BE IT REMEMBERED that on this 2nd day of December, 1986, personally came
before me, a Notary Public in and for the County and State aforesaid, Richard E.
Goodell, President of Morgan National Silica Co., a corporation of the State of
Delaware, the corporation described in and which executed the foregoing
certificate, known to me personally to be such, and he duly executed said
certificate before me and acknowledged the said certificate to be his act and
deed and the act and deed of said corporation, and that the facts stated therein
are true and that the seal affixed to said certificate and attested by the
Secretary of said corporation is the corporate seal of said corporation.

     IN WITNESS WHEREOF, I have hereunto set my hand and seal of office the day
and year aforesaid.

                                        /s/ Mary E. Phillips
                                        ----------------------------------------
                                                       Notary Public

                                        My Commission Expires: Sept. 10, 1996
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