<PAGE>

                                                                    EXHIBIT 10.6

                                                                  EXECUTION COPY


                   INTELLECTUAL PROPERTY SECURITY AGREEMENT

                        Dated as of September 30, 1999

                                    Between

                     BETTER MINERALS & AGGREGATES COMPANY,

                                      and

                    THE OTHER GRANTORS REFERRED TO HEREIN,

                                 as Grantors,
                                 -----------

                                      and

                          BANQUE NATIONALE DE PARIS,

                                   as Agent
                                   --------
<PAGE>

                               TABLE OF CONTENTS
                               -----------------

<TABLE>
<CAPTION>
SECTION                                                                                     Page
<S>                                                                                         <C>
Section 1.   Grant of Security...........................................................    1

Section 2.   Security for Obligations....................................................    3

Section 3.   Grantors Remain Liable......................................................    3

Section 4.   Representations and Warranties..............................................    3

Section 5.   Further Assurances..........................................................    5

Section 6.   Transfers and Other Liens...................................................    7

Section 7.   Agent Appointed Attorney-in-Fact............................................    7

Section 8.   Agent May Perform...........................................................    8

Section 9.   The Agent's Duties..........................................................    8

Section 10.  Remedies....................................................................    8

Section 11.  Indemnity and Expenses......................................................   10

Section 12.  Security Interest Absolute..................................................   10

Section 13.  Amendments; Waivers, Etc....................................................   10

Section 14.  Addresses for Notices.......................................................   11

Section 15.  Continuing Security Interest, Assignments under the Credit Agreement........   11

Section 16.  Release and Termination.....................................................   12

Section 17.  Execution in Counterparts...................................................   12

Section 18.  Governing Law, Submission to Jurisdiction, Waiver of Jury Trial; Etc........   12
</TABLE>

Schedule I     -  Patents and Patent Applications
Schedule II    -  Trademark Registrations, Trademark Applications and Common Law
               Trademarks
Schedule III   -  Copyright Registrations and Applications

                                       i
<PAGE>

Schedule IV    -  Licenses
Schedule V     -  Pending Litigation/Unauthorized Uses

Exhibit A      -  Intellectual Property Security Agreement Supplement

                                      ii
<PAGE>


                   INTELLECTUAL PROPERTY SECURITY AGREEMENT


          INTELLECTUAL PROPERTY SECURITY AGREEMENT, dated as of September 30,
1999, made between Better Minerals & Aggregates Company, a Delaware corporation
formerly known as "USS Intermediate Holdco, Inc." (the "Borrower"), each other
                                                        --------
grantor listed on the signature pages hereto (together with the Borrower, the
"Grantors" and, individually, a "Grantor"), and BANQUE NATIONALE DE PARIS
 --------
("BNP"), as agent (together with any successor agent appointed pursuant to
  ---
Article VII of the Credit Agreement (as hereinafter defined), the ("Agent") for
the Lender Parties (as defined in the Credit Agreement) and as custodian for the
Hedge Banks (as defined in the Credit Agreement).

                            PRELIMINARY STATEMENTS

          (1) The Borrower, BMAC Holdings, Inc., a Delaware corporation, and
George F. Pettinos (Canada) Limited, a corporation organized and existing under
the laws of Canada (the "Canadian Borrower"), have entered into a Credit
                         -----------------
Agreement dated as of September 30, 1999 (said Agreement, as it may hereafter be
amended, supplemented or otherwise modified from time to time, being the "Credit
                                                                          ------
Agreement"; the terms defined therein and not otherwise defined herein being
---------
used herein as therein defined) with certain Lender Parties party thereto and
Banque Nationale de Paris, as Agent for such Lender Parties and as Swing Line
Bank and Initial Issuing Bank.

          (2) It is a condition precedent to the making of Advances and Drawings
and the issuance of Letters of Credit by the Lender Parties and the entry by the
Hedge Banks into the Bank Hedge Agreements with the Loan Parties under the
Credit Agreement that the Grantors shall have executed and delivered this
Intellectual Property Security Agreement.

          NOW, THEREFORE, in consideration of the premises and in order to
induce the Lender Parties to make Advances and Drawings and to issue Letters of
Credit under the Credit Agreement and to induce the Hedge Banks to enter into
Bank Hedge Agreements with the Loan Parties from time to time, the Grantors
hereby agree with the Agent for the ratable benefit of the Secured Parties as
follows:
<PAGE>

          Section 1. Grant of Security. Each Grantor hereby assigns and pledges
                     -----------------
to the Agent for the ratable benefit of the Secured Parties, and hereby grants
to the Agent for the ratable benefit of the Secured Parties a security interest
in, the following, in each case, as to each type of property described below,
whether now owned or hereafter acquired, wherever located and whether now or
hereafter existing (collectively, the "Intellectual Property Collateral"):
                                       --------------------------------

          (a) all patents, patent applications and patentable inventions,
     including, without limitation, each patent and patent application
     identified in Schedule I attached hereto and made a part hereof, and
     including without limitation (i) all inventions and improvements described
     and claimed therein, (ii) the right to sue or otherwise recover for any
     infringements thereof, (iii) all income, royalties, damages and other
     payments now and hereafter due and/or payable with respect thereto
     (including, without limitation, payments under all licenses entered into in
     connection therewith, and damages and payments for past and future
     infringements thereof), and (iv) all rights corresponding thereto
     throughout the world and all reissues, divisions, continuations,
     continuations-in-part, substitutes, renewals, and extensions thereof, all
     improvements thereon and all other rights of any kind whatsoever of such
     Grantor accruing thereunder or pertaining thereto (the "Patents");
                                                             -------

          (b) all trademarks, service marks, trade names, trade dress or other
     indicia of trade origin, trademark and service mark registrations, and
     applications for trademark or service mark registrations and any renewals
     thereof, including, without limitation, each registration and application
     identified in Schedule II attached hereto and made a part hereof, and
     including without limitation (i) the right to sue or otherwise recover for
     any and all past, present and future infringements and dilutions thereof,
     (ii) all income, royalties, damages and other payments now and hereafter
     due and/or payable with respect thereto (including, without limitation,
     payments under all licenses entered into in connection therewith, and
     damages and payments for past or future infringements thereof), and (iii)
     all rights corresponding thereto throughout the world and all other rights
     of any kind whatsoever of such Grantor accruing thereunder or pertaining
     thereto, together in each case with the goodwill of the business connected
     with the use of, and symbolized by, each such trademark, service mark,
     trade name, trade dress or other indicia of trade origin (the
     "Trademarks"), provided, however, that the Trademarks shall not include any
      ----------
     trademark applications filed in the United States Patent and Trademark
     Office under 15 U.S.C. (S) 1051(b) prior to the filing of a verified
     statement of use under 15 U.S.C. (S) 1051(d) to the extent that a valid
     security interest may not be taken in such an intent-to-use trademark
     application under applicable law;

          (c) all copyrights, whether statutory or common law, and whether or
     not the underlying works of authorship have been published, and all works
     of authorship and other intellectual property rights therein, all
     copyrights of works based on, incorporated in, derived from or relating to
     works covered by such copyrights, all right, title and interest to make and
     exploit all derivative works based on or adopted from works covered by such
     copyrights, and all copyright registrations and copyright applications, and
     any renewals or extensions thereof, including, without limitation, each
     copyright registration
<PAGE>

                                       3

     and copyright application identified in Schedule III attached hereto and
     made a part hereof, and including, without limitation, (i) the right to
     print, publish and distribute any of the foregoing, (ii) the right to sue
     or otherwise recover for any and all past, present and future infringements
     and misappropriations thereof, (iii) all income, royalties, damages and
     other payments now and hereafter due and/or payable with respect thereto
     (including, without limitation, payments under all licenses entered into in
     connection therewith, and damages and payments for past or future
     infringements thereof), and (iv) all rights corresponding thereto
     throughout the world and all other rights of any kind whatsoever of such
     Grantor accruing thereunder or pertaining thereto (the "Copyrights");
                                                             ----------

          (d) all license agreements with any other person in connection with
     any of the Patents or Trademarks or Copyrights, or such other person's
     patents, trade names, trademarks or copyrights, whether such Grantor is a
     licensor or licensee under any such license agreement, in each case, to the
     extent such license agreements do not prohibit such Grantor from granting a
     security interest in its rights thereunder, including, without limitation,
     the license agreements listed on Schedule IV attached hereto and made a
     part hereof, and any right to prepare for sale, sell and advertise for
     sale, all Inventory (as defined in the Security Agreement) now or hereafter
     owned by such Grantor and now or hereafter covered by such licenses (the
     "Licenses");
      --------

          (e) confidential and proprietary information, including know-how,
     trade secrets, manufacturing and production processes and techniques,
     inventions, research and development information, technical data,
     financial, marketing and business data, pricing and cost information,
     business and marketing plans, and customer and supplier lists and
     information, and including, without limitation, (i) the right to sue or
     otherwise recover for any and all past, present and future
     misappropriations thereof, and (ii) all income, royalties, damages and
     other payments now and hereafter due and/or payable with respect thereto
     (including, without limitation, payments under all licenses entered into in
     connection therewith, and damages and payments for past or future
     misappropriations thereof); provided, that such grant shall only be
                                 --------
     effective to the extent the grant by such Grantor of a security interest
     pursuant to this Agreement in its right, title and interest in any of the
     foregoing is not prohibited by law, contract or otherwise without the
     consent of any person or would not give any other person the right to
     terminate its obligations with respect thereto (the "Trade Secrets"); and
                                                          -------------

          (f) all computer software programs and data bases (including source
     code, object code and all related applications and data files), firmware,
     and documentation and materials relating thereto, and all rights with
     respect to the foregoing, including, without limitation, any and all
     options, warranties, service contracts, program services, test rights,
     maintenance rights, improvement rights, renewal rights and indemnifications
     and any substitutions, replacements, additions or model conversions of any
     of the foregoing;
<PAGE>

                                       4

     provided, that such grant shall only be effective to the extent the grant
     --------
     by such Grantor of a security interest pursuant to this Agreement in its
     right, title and interest in any of the foregoing is not prohibited by law,
     contract or otherwise without the consent of any person or would not give
     any other person the right to terminate its obligations with respect
     thereto (the "Computer Software").
                   -----------------

          Section 2.  Security for Obligations.  This Agreement secures the
                      ------------------------
payment of all Obligations of each Grantor now or hereafter existing under the
Loan Documents, whether for principal, interest, fees, expenses or otherwise
(all such Obligations being the "Secured Obligations").  Without limiting the
                                 -------------------
generality of the foregoing, this Agreement secures the payment of all amounts
that constitute part of the Secured Obligations and would be owed by such
Grantor to the Secured Parties under the Loan Documents but for the fact that
they are unenforceable or not allowable due to the existence of a bankruptcy,
reorganization or similar proceeding involving such Grantor.

          Section 3.  Grantors Remain Liable.  Anything herein to the contrary
                      ----------------------
notwithstanding, (a) each Grantor shall remain liable under the contracts and
agreements included in the Intellectual Property Collateral to the extent set
forth therein to perform all of its duties and obligations thereunder to the
same extent as if this Agreement had not been executed, (b) the exercise by the
Agent of any of the rights hereunder shall not release any Grantor from any of
its duties or obligations under the contracts and agreements included in the
Intellectual Property Collateral and (c) no Secured Party shall have any
obligation or liability under the contracts and agreements included in the
Intellectual Property Collateral by reason of this Agreement or any other Loan
Document, nor shall any Secured Party be obligated to perform any of the
obligations or duties of any Grantor thereunder or to take any action to collect
or enforce any claim for payment assigned hereunder.

          Section 4.  Representations and Warranties.  Each Grantor represents
                      ------------------------------
and warrants as to itself and its Intellectual Property Collateral as follows:

          (a) Such Grantor is the legal, beneficial, sole and exclusive owner of
     the Intellectual Property Collateral free and clear of any Lien, except for
     the Liens permitted in the Loan Documents.  No effective financing
     statement or other instrument similar in effect covering all or any part of
     the Intellectual Property Collateral is on file in any recording office,
     except such as may have been filed in favor of the Agent relating to this
     Agreement or as permitted in the Loan Documents.

          (b) Set forth in Schedule I hereto is a complete and accurate list as
     of the date hereof of all patents and all patent applications owned by such
     Grantor.  Set forth in Schedule II hereto is a complete and accurate list
     as of the date hereof of all trademark and service mark registrations and
     all trademark and service mark applications owned by such Grantor.  Set
     forth in Schedule III hereto is a complete and accurate list as of the date
     hereof of all copyright registrations and copyright applications owned by
<PAGE>

                                       5

     such Grantor.  Set forth in Schedule IV hereto is a complete and accurate
     list as of the date hereof of all Licenses owned by such Grantor in which
     such Grantor is (i) a licensor with respect to any of the Patents,
     Trademarks or Copyrights, or (ii) a licensee of any other person's patents,
     trade names, trademarks, or copyrights.

          (c) As of the date of this Agreement, each patent, patent application,
     trademark or service mark registration, trademark or service mark
     application, copyright registration and copyright application of such
     Grantor set forth in Schedules I, II and III is subsisting and has not been
     adjudged invalid, unregistrable or unenforceable, in whole or in part, and
     is valid, registrable and enforceable.  As of the date of this Agreement,
     each License of such Grantor identified in Schedule IV is validly
     subsisting and has not been adjudged invalid or unenforceable, in whole or
     in part, and is valid and enforceable.  Such Grantor has notified the Agent
     in writing of all uses of which it is aware, as of the date of this
     Agreement, of any item of Intellectual Property Collateral which could
     reasonably be expected to lead to such item becoming invalid or
     unenforceable, including unauthorized uses by third parties and uses which
     were not supported by the goodwill of the business connected with such
     Intellectual Property Collateral.

          (d) As of the date of this Agreement, such Grantor has not made a
     previous assignment, transfer or agreement constituting a present or future
     assignment, transfer or encumbrance of any of the Intellectual Property
     Collateral.  As of the date of this Agreement, such Grantor has not granted
     any license (other than those listed on Schedule IV hereto), release,
     covenant not to sue, or non-assertion assurance to any person with respect
     to any part of the Intellectual Property Collateral.

          (e) Such Grantor has used its sound business judgment in utilizing
     statutory notice in a commercially reasonable manner in connection with its
     use of each patent, each registered trademark and registered service mark
     and each copyright contained in Schedules I, II and III.

          (f) Except to the extent set forth on Schedule 4.01(d) to the Credit
     Agreement, all filings and other actions necessary or desirable to perfect
     and preserve the security interest in the United States Intellectual
     Property Collateral created under this Agreement have been duly made or
     taken.  This Agreement, together with such filings and other actions, upon
     the filing of financing and continuation statements under the Uniform
     Commercial Code and the recording of the security interest and lien
     provisions of this Agreement with the United States Patent and Trademark
     Office and the United States Copyright Office, creates a valid and
     perfected security interest in the Intellectual
<PAGE>

                                       6

     Property Collateral, securing the payment of the Secured Obligations
     subject in priority only to the liens and security interests permitted in
     the Loan Documents.

          (g) Except to the extent set forth on Schedule 4.01(d) to the Credit
     Agreement, no consent of any Person and no authorization, approval or other
     action by, and no notice to or filing with, any governmental authority or
     regulatory body or any other third party is required (i) for the grant by
     such Grantor of the assignment and security interest granted hereunder, for
     the pledge by such Grantor of the Intellectual Property Collateral pursuant
     hereto or for the execution, delivery or performance of this Agreement by
     such Grantor, (ii) for the perfection or maintenance of the pledge,
     assignment and security interest created hereunder (including the first
     priority nature of such pledge, assignment or security interest subject
     only to the liens and security interests permitted in the Loan Documents)
     or (iii) for the exercise by the Agent of its rights provided for in this
     Agreement or the remedies in respect of the Intellectual Property
     Collateral pursuant to this Agreement, in each case other than the filing
     of financing and continuation statements under the Uniform Commercial Code
     and the recording of the security interest and lien provisions of this
     Agreement with the United States Patent and Trademark Office and the United
     States Copyright Office which shall be duly filed promptly following the
     execution of this Agreement.

          (h) Except for the Licenses set forth in Schedule IV and except as set
     forth in Schedule V hereto, as of the date of this Agreement, such Grantor
     has no knowledge of the existence of any right or any claim that is likely
     to be made by any third party relating to any item of Intellectual Property
     Collateral.

          (i) Except as set forth in Schedule V, as of the date of this
     Agreement, no claim has been made and is continuing or threatened that any
     item of Intellectual Property Collateral is invalid or unenforceable or
     that the use by such Grantor of any Intellectual Property Collateral does
     or may violate the rights of any Person.  Except as set forth in Schedule
     V, as of the date of this Agreement, to the best of such Grantor's
     knowledge, there is no infringement or unauthorized use of any item of
     Intellectual Property Collateral.

          Section 5.  Further Assurances.  (a)  Each Grantor agrees that from
                      ------------------
time to time, at its own expense, it shall promptly execute and deliver all
further instruments and documents, and take all further action, that may be
reasonably necessary or customary that the Agent may request, in order to
perfect and preserve any pledge, assignment or security interest granted or
purported to be granted hereby or to enable the Agent to exercise and enforce
its rights and remedies hereunder with respect to any Intellectual Property
Collateral.  Without limiting the generality of the foregoing, each Grantor will
execute and file such financing or continuation statements, or amendments
thereto, and such other instruments or notices, as may be reasonably necessary
or customary as the Agent may request, in order to perfect and preserve the
pledge,
<PAGE>

                                       7

assignment and security interest granted or purported to be granted hereby or to
enable the Agent to exercise and enforce its rights and remedies hereunder with
respect to the Intellectual Property Collateral.

          (b) Each Grantor hereby authorizes the Agent to file one or more
financing or continuation statements, and amendments thereto, relating to all or
any part of the Intellectual Property Collateral without the signature of such
Grantor where permitted by law upon which evidence of such filing shall be sent
promptly to such Grantor.  A photocopy or other reproduction of this Agreement
or any financing statement covering the Intellectual Property Collateral or any
part thereof shall be sufficient as a financing statement where permitted by
law.

          (c) Each Grantor shall furnish to the Agent from time to time
statements and schedules further identifying and describing the Intellectual
Property Collateral and such other reports in connection with the Intellectual
Property Collateral as the Agent may reasonably request, all in reasonable
detail.

          (d) Each Grantor agrees that, should it obtain an ownership interest
in any patent, patent application, patentable invention, trademark, service
mark, trade name, trade dress, other indicia of trade origin, trademark or
service mark registration, trademark or service mark application, copyright,
work of authorship, copyright registration, copyright application or License,
which is not now a part of the Intellectual Property Collateral, (i) the
provisions of Section 1 will automatically apply thereto, and (ii) any such
patent, patent application, patentable invention, trademark, service mark, trade
name, trade dress, indicia of trade origin, trademark or service mark
registration or trademark or service mark application (together with the
goodwill of the business connected with the use of same and symbolized by same),
copyright, work of authorship, copyright registration, copyright application or
License will automatically become part of the Intellectual Property Collateral.
Each Grantor shall provide to the Agent on a semi-annual basis, beginning on
March 31, 2000, a written report indicating any ownership interest in any
patent, patent application, trademark or service mark registration, trademark or
service mark application, copyright registration or copyright application, or
License that it should obtain (or License that it should grant) during the
immediately previous six month period.  Each Grantor authorizes the Agent to
modify this Agreement by amending Schedules I, II, III, IV and V (and will
cooperate with the Agent in effecting any such amendment) to include any patent,
patent application, trademark or service mark registration, trademark or service
mark application, copyright registration, copyright application or License which
becomes part of the Intellectual Property Collateral under this Section.

          (e) With respect to each patent, patent application, trademark or
service mark registration, trademark or service mark application, copyright
registration, copyright application and License, each Grantor agrees to take all
steps it deems necessary or appropriate, including, without limitation, in the
United States Patent and Trademark Office, the United States
<PAGE>

                                       8

Copyright Office or in any court, to (i) maintain each such patent, trademark or
service mark registration, copyright registration and License, and (ii) pursue
each such patent application, trademark or service mark application, and
copyright application now or hereafter included in the Intellectual Property
Collateral, including, without limitation, the filing of responses to office
actions issued by the United States Patent and Trademark Office and the United
States Copyright Office, the filing of applications for renewal or extension,
the filing of affidavits under Sections 8 and 15 of the United States Trademark
Act, the filing of divisional, continuation, continuation-in-part and substitute
applications, the filing of applications for re-issue, renewal or extensions,
the payment of maintenance fees, and the participation in interference,
reexamination, opposition, cancellation, infringement and misappropriation
proceedings. Each Grantor agrees to take corresponding steps with respect to
each new or acquired patent, patent application, trademark or service mark
registration, trademark or service mark application, copyright registration,
copyright application or License to which it is now or later becomes entitled.
Any expenses incurred in connection with such activities will be borne by such
Grantor. The Grantors shall not discontinue use of or otherwise abandon any
patent, patent application, trademark or service mark registration, trademark or
service mark application, copyright registration or copyright application now
owned or hereafter acquired or filed, or abandon any right to file any
application for any patent, trademark or copyright, unless the applicable
Grantor shall have previously determined using its sound business judgment that
such use or pursuit or maintenance of the same is no longer desirable in the
conduct of such Grantor's business, in which case, such Grantor will give notice
of any such abandonment or discontinuance to the Agent pursuant to the semi-
annual reporting requirement contained in Section 5(d) above, provided that, in
no event, shall such Grantor discontinue use or otherwise abandon any of the
Intellectual Property Collateral now owned or hereafter acquired or filed, or
abandon any right to file any application to obtain any Intellectual Property
Collateral, if such act, either alone or in aggregation with other such acts, is
reasonably expected to have a Material Adverse Effect.

          (f) Each Grantor agrees to notify the Agent promptly and in writing if
it learns (i) that any item of the Intellectual Property Collateral has been
determined to have become abandoned or dedicated or (ii) of any adverse
determination or the institution of any proceeding (including, without
limitation, the institution of any proceeding in the United States Patent and
Trademark Office or any court) regarding any item of the Intellectual Property
Collateral, and such abandonment, dedication, adverse determination or
proceeding is reasonably expected to have a Material Adverse Effect.

          (g) In the event that any Grantor becomes aware that any of the
patents, patent applications, trademark and service mark registrations,
trademark and service mark applications, copyright registrations and copyright
applications contained on Schedules I, II and III to this Agreement is infringed
or misappropriated by a third party, such Grantor will promptly notify the Agent
and will take such actions, if any, as such Grantor in its sound business
judgment deems reasonable and appropriate under the circumstances to protect the
same, including, without
<PAGE>

                                       9

limitation, suing for infringement or misappropriation and for an injunction
against such infringement or misappropriation. Any expense incurred in
connection with such activities will be borne by such Grantor.

          (h) Each Grantor will continue to use its sound business judgment in
utilizing statutory notice in a commercially reasonable manner in connection
with its use of each of its patents, registered trademarks and service marks,
and copyrights contained in Schedules I, II and III.

          (i) Each Grantor will take all steps which it in its sound business
judgment deems reasonable and appropriate under the circumstances to preserve
and protect its Intellectual Property Collateral, including, without limitation,
maintaining the quality of any and all products or services used or provided in
connection with any of the registered trademarks or registered service marks
contained on Schedule II hereto, consistent with sound business practices, and
taking all steps it deems necessary or appropriate to ensure that all licensed
users of any of such registered trademarks or registered service marks use such
consistent standards of quality.

          Section 6.  Transfers and Other Liens.  Each Grantor agrees not (i) to
                      -------------------------
sell, assign (by operation of law or otherwise) or otherwise dispose of, or
grant any option with respect to, any of the Intellectual Property Collateral,
except sales, assignments and dispositions otherwise permitted under Section
5.02(e) of the Credit Agreement or in Section 5(e) hereof, or (ii) to create or
suffer to exist any Lien upon or with respect to any of the Intellectual
Property Collateral except for the pledge, assignment and security interest
created under this Agreement and the Liens permitted under Section 5.02(a) of
the Credit Agreement.

          Section 7.  Agent Appointed Attorney-in-Fact.  Each Grantor hereby
                      --------------------------------
irrevocably appoints the Agent such Grantor's attorney-in-fact, with full
authority in the place and stead of such Grantor and in the name of such Grantor
or otherwise, upon (i) the occurrence and during the continuance of an Event of
Default and (ii) the making of the request or the granting of the consent
specified by Section 6.01 of the Credit Agreement to authorize the Agent to
declare the Advances and any amounts otherwise due and payable pursuant to the
provisions of such Section 6.01 or the making of the demand specified in Section
6.02 of the Credit Agreement to require the Borrower to pay amounts in respect
of Letters of Credit or the Canadian Borrower to pay amounts in respect of
Bankers' Acceptances, and upon notice to such Grantor, to take any action and to
execute any instrument that the Agent may deem reasonably necessary or advisable
to accomplish the purposes of this Agreement, including, without limitation:

          (a) to ask for, demand, collect, sue for, recover, compromise, receive
     and give acquittance and receipts for moneys due and to become due under or
     in respect of any of the Intellectual Property Collateral,
<PAGE>

                                      10

          (b) to receive, indorse and collect any drafts or other instruments,
     documents and chattel paper, in connection with clause (a) above, and

          (c) to file any claims or take any action or institute any proceedings
     that the Agent may deem reasonably necessary or desirable for the
     collection of any payments relating to any of the Intellectual Property
     Collateral or otherwise to enforce the rights of the Agent with respect to
     any of the Intellectual Property Collateral; provided that the Agent shall
                                                  --------
     act with reasonable care in the exercise of the foregoing; and provided,
                                                                    --------
     further, that the Agent shall give such Grantor not less than ten Business
     -------
     Days prior written notice of the time and place of any sale or other
     intended disposition of the Intellectual Property Collateral.

          Section 8.  Agent May Perform.  Upon and during the continuance of an
                      -----------------
Event of Default, if any Grantor fails to perform any agreement contained
herein, the Agent may itself perform, or cause performance of, such agreement,
and the expenses of the Agent incurred in connection therewith shall be payable
by such Grantor under Section 11(b).

          Section 9.  The Agent's Duties.  The powers conferred on the Agent
                      ------------------
hereunder are solely to protect its interest in the Intellectual Property
Collateral and, beyond the exercise of reasonable care, shall not impose any
duty upon it to exercise any such powers.  Except for the safe custody of the
certificates of registration for any of the Trademarks or Copyrights or the
letters patent for any of the Patents in its possession and the accounting for
moneys actually received by it hereunder, the Agent shall have no duty as to any
Intellectual Property Collateral, whether or not the Agent or any other Secured
Party has or is deemed to have knowledge of such matters, or as to the taking of
any necessary steps to preserve rights against any parties or any other rights
pertaining to any Intellectual Property Collateral, in each case, beyond the
exercise of reasonable care.  The Agent shall be deemed to have exercised
reasonable care in the custody and preservation of the certificates of
registration for any of the Trademarks or Copyrights or the letters patent for
any of the Patents in its possession if such certificates of registration and
letters patent are accorded treatment substantially equal to that which it
accords its own property.
<PAGE>

                                      11

          Section 10.  Remedies.  If (i) any Event of Default shall have
                       --------
occurred and be continuing and (ii) the making of the request or the granting of
the consent specified by Section 6.01 of the Credit Agreement to authorize the
Agent to declare the Advances due and payable pursuant to the provisions of such
Section 6.01 or the making of the demand specified in Section 6.02 of the Credit
Agreement to require the Borrower to pay amounts in respect of Letters of Credit
or the Canadian Borrower to pay amounts in respect of Bankers' Acceptances shall
have occurred:

          (a) The Agent may exercise in respect of the Intellectual Property
     Collateral, in addition to other rights and remedies provided for herein or
     otherwise available to it, all the rights and remedies of a secured party
     upon default under the Uniform Commercial Code in effect in the State of
     New York at such time (the "N.Y. Uniform Commercial Code") (whether or not
                                 ----------------------------
     the N.Y. Uniform Commercial Code applies to the affected Intellectual
     Property Collateral), and also may (i) require each Grantor to, and each
     Grantor hereby agrees that it will at its expense and upon request of the
     Agent forthwith, assemble all or part of the documents and things embodying
     any part of the Intellectual Property Collateral as directed by the Agent
     (to the extent permitted by applicable law and without breach of the peace)
     and make them available to the Agent at a place and time to be designated
     by the Agent that is reasonably convenient to both parties and (ii) without
     notice except as specified below, sell the Intellectual Property Collateral
     or any part thereof in one or more parcels at public or private sale, at
     any of the Agent's offices or elsewhere, for cash, on credit or for future
     delivery, and upon such other terms as the Agent may deem commercially
     reasonable.  In the event of any sale, assignment, or other disposition of
     any of the Intellectual Property Collateral, the goodwill of the business
     connected with and symbolized by any Trademarks subject to such disposition
     will be included, and each Grantor will supply to the Agent or its designee
     such Grantor's know-how and expertise, and the documents and things
     embodying the same, relating to the manufacture, distribution, advertising
     and sale of products or the provision of services relating to any
     Intellectual Property Collateral subject to such disposition, and such
     Grantor's customer lists and other records and documents relating to such
     Intellectual Property Collateral and to the manufacture, distribution,
     advertising and sale of such products and services.  Each Grantor agrees
     that, to the extent notice of sale shall be required by law, at least ten
     days' notice to such Grantor of the time and place of any public sale or
     the time after which any private sale is to be made shall constitute
     reasonable notification.  The Agent shall not be obligated to make any sale
     of Intellectual Property Collateral regardless of notice of sale having
     been given.  The Agent may adjourn any public or private sale from time to
     time by announcement at the time and place fixed therefor, and such sale
     may, without further notice, be made at the time and place to which it was
     so adjourned.
<PAGE>

                                      12

          (b)  All cash proceeds received by the Agent in respect of any sale
     of, collection from, or other realization upon, all or any part of the
     Intellectual Property Collateral shall be applied (after payment of any
     amounts payable to the Agent pursuant to Section 11) by the Agent for the
     ratable benefit of the Secured Parties against the Secured Obligations in
     such order as the Agent shall elect. Any surplus of such cash or cash
     proceeds held by the Agent and remaining after payment in full of all the
     Secured Obligations shall be paid over to the applicable Grantor or its
     successor or assigns, or as a court of competent jurisdiction may direct.

          (c)  The Agent may exercise any and all rights and remedies of each
     Grantor in respect of the Intellectual Property Collateral.

          (d)  All payments received by any Grantor under or in connection with
     any Intellectual Property Collateral shall be received in trust for the
     benefit of the Agent, shall be segregated from other funds of such Grantor
     and shall be forthwith paid over to the Agent in the same form as so
     received (with any necessary endorsement).

          Section 11.  Indemnity and Expenses.  (a)  Each Grantor agrees jointly
                       ----------------------
and severally to indemnify the Secured Parties in connection with any claims,
losses and liabilities resulting from this Agreement to the extent required by,
and in accordance with the provisions of, Section 8.04(b) of the Credit
Agreement as if such Grantor were a party to the Credit Agreement.

          (b)  Each Grantor agrees jointly and severally to pay to the Agent
such amounts of any fees and expenses incurred by the Agent in connection with
the administration of the Agreement as is required by, and in accordance with
the provisions of, Sections 8.04(a) and (b) of the Credit Agreement as if such
Grantor were a party to the Credit Agreement.

          Section 12.  Security Interest Absolute.  The obligations of each
                       --------------------------
Grantor under this Agreement are independent of the Secured Obligations, and a
separate action or actions may be brought and prosecuted against any Grantor to
enforce this Agreement.  All rights of the Agent and the pledge, assignment and
security interest hereunder, and all obligations of each Grantor hereunder,
shall be absolute and unconditional, irrespective of:

          (i)  any lack of validity or enforce ability  of  any  Loan  Document,
     any Bank Hedge Agreement or any other agreement or instrument relating
     thereto;

          (ii) any change in the time, manner or place of payment of, or in any
     other term of, all or any of the Secured Obligations, or any other
     amendment or waiver of or any consent to any departure from any Loan
     Document or any Bank Hedge Agreement,
<PAGE>

                                      13

     including, without limitation, any increase in the Secured Obligations
     resulting from the extension of additional credit to any Grantor or any of
     its Subsidiaries or otherwise;

          (iii) any taking, exchange, release or non-perfection of any other
     collateral, or any taking, release or amendment or waiver of or consent to
     departure from any guaranty, for all or any of the Secured Obligations;

          (iv)  any manner of application of collateral, or proceeds thereof, to
     all or any of the Secured Obligations, or any manner of sale or other
     disposition of any collateral for all or any of the Secured Obligations or
     any other assets of any Grantor or any of its Subsidiaries;

          (v)   any change, restructuring or termination of the corporate
     structure or existence of any Grantor or any of its Subsidiaries; or

          (vi)  any other circumstance that might otherwise constitute a defense
     available to, or a discharge of, any Grantor or a third-party grantor of a
     security interest.

This Agreement shall continue to be effective or be reinstated, as the case may
be, if at any time any payment of any of the Secured Obligations is rescinded or
must otherwise be returned by any Secured Party or by any other Person upon the
insolvency, bankruptcy or reorganization of any Loan Party or otherwise, all as
though such payment had not been made.

          Section 13.  Amendments; Waivers, Etc.  (a)  No amendment or waiver of
                       ------------------------
any provision of this Agreement, and no consent to any departure by any Grantor
herefrom, shall in any event be effective unless the same shall be in writing
and signed by the Agent, and then such waiver or consent shall be effective only
in the specific instance and for the specific purpose for which given.

          (b)   No failure on the part of the Agent, any Lender Party or any
Hedge Bank to exercise, and no delay in exercising, any right, power or
privilege hereunder shall operate as a waiver thereof or consent thereto; nor
shall any single or partial exercise of any such right, power or privilege
preclude any other or further exercise thereof or the exercise of any other
right, power or privilege.

          (c)   Upon the execution and delivery by any Person of an intellectual
property security agreement supplement in substantially the form of Exhibit A
hereto (each an "Intellectual Property Security Agreement Supplement"), (i) such
                 ---------------------------------------------------
Person shall be referred to as an "Additional Grantor" and shall be and become a
Grantor, and each reference in this Agreement to "Grantor" or "Grantors" shall
also mean and be a reference to such Additional Grantor and (ii) the schedules
attached to such Intellectual Property Security Agreement
<PAGE>

                                      14

Supplement shall be incorporated into and become a part of and supplement
Schedules I through IV hereto, and the Agent may attach such Schedules as
supplements to such Schedules, and each reference to such Schedules shall mean
and be a reference to such Schedules, as supplemented pursuant hereto.

          (d) Delivery by telecopier of an executed counterpart of any amendment
or waiver of any provision of this Agreement or of any Supplement or Schedule
hereto shall be effective as delivery of a manually executed counterpart
thereof.

          Section 14.  Addresses for Notices.  All notices and other
                       ---------------------
communications provided for hereunder shall be in writing (including telecopier
or telegraphic communication) and mailed, telecopied, telegraphed, cabled or
delivered, if to a Grantor, c/o Better Minerals & Aggregates Company, Route 522
North, P.O. Box 187, Berkeley Springs, WV 25411, Attention: Chief Financial
Officer, telecopier number (304) 258-3500, and if to the Agent, any Lender
Party, the Issuing Bank or any Hedge Bank, addressed to it at its address set
forth in Section 8.02 of the Credit Agreement, or, as to any party at such other
address as shall be designated by such party in a written notice to each other
party complying as to delivery with the terms of this Section 14.  All such
notices and other communications shall, when mailed, telecopied or telegraphed,
be effective when received by the addressee.

          Section 15.  Continuing Security Interest, Assignments under the
                       ---------------------------------------------------
Credit Agreement.  This Agreement shall create a continuing security interest in
----------------
the Intellectual Property Collateral and shall (a) remain in full force and
effect until the latest of the payment in full in cash of the Secured
Obligations constituting an Advance or other Secured Obligations then due and
payable, the Termination Date and the termination or expiration of all Bank
Hedge Agreements or as otherwise permitted thereunder, (b) be binding upon each
Grantor, its successors and assigns and (c) inure, together with the rights and
remedies of the Agent hereunder, to the benefit of the Secured Parties and their
respective successors, transferees and assigns.  Without limiting the generality
of the foregoing clause (c), any Lender may assign or otherwise transfer all or
any portion of its rights and obligations under the Credit Agreement (including,
without limitation, all or any portion of its Commitment, the Advances owing to
it and the Note or Notes held by it) to any other Person, and such other Person
shall thereupon become vested with all the benefits in respect thereof granted
to such Lender herein or otherwise, in each case as provided in Section 8.07 of
the Credit Agreement.

          Section 16.  Release and Termination.  (a)  Upon any sale, lease,
                       -----------------------
transfer or other disposition of any item of Intellectual Property Collateral in
accordance with the terms of the Loan Documents, the Agent will, at the
applicable Grantor's expense, execute and deliver to such Grantor such documents
as such Grantor shall reasonably request to evidence the release of such item of
Intellectual Property Collateral from the assignment and security interest
granted hereby; provided, however, that (i) at the time of such request and such
                --------  -------
release, no Event of Default shall
<PAGE>

                                      15

have occurred and be continuing, (ii) except to the extent such sale, lease or
transfer or other disposition is permitted under Section 5.02(e) of the Credit
Agreement, such Grantor shall have delivered to the Agent, at least ten Business
Days prior to the date of the proposed release, a written request for release
describing the item of the Intellectual Property Collateral and the terms of the
sale, lease, transfer or other disposition in reasonable detail, including,
without limitation, the price thereof and any expenses in connection therewith,
together with a form of release for execution by the Agent and a certification
by such Grantor to the effect that the transaction is in compliance with the
Loan Documents and as to such other matters as the Agent may reasonably request
and (iii) the proceeds of any such sale, lease, transfer or other disposition
required to be applied in accordance with Section 2.07 of the Credit Agreement
shall be paid to, or in accordance with the instructions of, the Agent at the
closing.

          (b) Upon the latest of the payment in full in cash of the Secured
Obligations constituting an Advance or other Secured Obligations then due and
payable, the Termination Date and the termination or expiration of all Bank
Hedge Agreements, the pledge, assignment and security interest granted hereby
shall terminate and all rights to the Intellectual Property Collateral shall
revert to the Grantors.  Upon any such termination, the Agent will, at the
Grantors' expense, execute and deliver to the Grantors such documents as the
Grantors shall reasonably request to evidence such termination and promptly
release and return the Intellectual Property Collateral in its possession.

          Section 17.  Execution in Counterparts. This Agreement may be executed
                       -------------------------
in any number of counterparts and by different parties hereto in separate
counterparts, each of which when so executed shall be deemed to be an original
and all of which taken together shall constitute one and the same agreement.
Delivery of an executed counterpart of a signature page to this Agreement by
telecopier shall be effective as delivery of a manually executed counterpart of
this Agreement.

          Section 18.  Governing Law, Submission to Jurisdiction, Waiver of Jury
                       ---------------------------------------------------------
Trial; Etc. (a) This Agreement shall be governed by and construed in accordance
----------
with the laws of the State of New York, except to the extent that the validity
or perfection of the security interest hereunder, or remedies hereunder, in
respect of any particular Intellectual Property Collateral are governed by the
laws of a jurisdiction other than the State of New York. Unless otherwise
defined herein or in the Credit Agreement, terms used in Article 9 of the Code
are used herein as therein defined.

          (b) Each Grantor hereby irrevocably and unconditionally submits, for
itself and its property, to the nonexclusive jurisdiction of any New York State
court or federal court of the United States of America sitting in New York City,
and any appellate court from any thereof, in any action or proceeding arising
out of or relating to this Agreement or any other Loan Document or Bank Hedge
Agreement to which it is or is to be a party, or for recognition and
<PAGE>

                                      16

enforcement of any judgment, and each Grantor hereby irrevocably and
unconditionally agrees that all claims in respect of any such action or
proceeding may be heard and determined in any such New York State or, to the
extent permitted by law, in such federal court. Each Grantor irrevocably and
unconditionally waives, to the fullest extent it may legally and effectively do
so, any objection or defense that it may now or hereafter have to the laying of
venue of any suit, action or proceeding arising out of or relating to this
Agreement or any of the other Loan Documents to which it is or is to be a party
in any New York State or federal court. Each Grantor hereby irrevocably waives,
to the fullest extent permitted by law, the defense of an inconvenient forum to
the maintenance of such action or proceeding in any such court. Each Grantor
agrees that a final judgment in any such action or proceeding shall be
conclusive and may be enforced in other jurisdictions by suit on the judgment or
in any other manner provided by law. Nothing herein shall affect the right that
any party may otherwise have to commence or participate in any action, suit or
proceeding relating to this Agreement, any of the other Loan Documents or any
Bank Hedge Agreement to which it is or is to be a party, or otherwise proceed
against any Grantor, in any other jurisdiction.

          (c) Each Grantor irrevocably consents to the service of any and all
process in any such action, suit or proceeding at the address set forth below
its name on the signature page hereof by any method permitted by law.

          (d) To the extent that any Grantor has or hereafter may acquire
immunity from jurisdiction of any court or from any legal process (whether
through service or notice, attachment prior to judgment, attachment in aid of
execution, execution or otherwise) with respect to itself or its property, such
Grantor hereby irrevocably waives such immunity in respect of its Obligations
under this Agreement, any other Loan Document and any Bank Hedge Agreement to
which it is or is to be a party.
          (e) Each Grantor irrevocably waives all right to trial by jury in any
action, proceeding or counterclaim (whether based on contract, tort or
otherwise) arising out of or relating to this Agreement, any other Loan Document
or any Bank Hedge Agreement, the transactions contemplated hereby or thereby or
the actions of the Agent, any Lender Party or any Hedge Bank in the negotiation,
administration, performance or enforcement thereof.

          IN WITNESS WHEREOF, each of the parties has caused this Agreement to
be duly executed and delivered by its officer thereunto duly authorized as of
the date first above written.


                                              BETTER MINERALS & AGGREGATES
                                              COMPANY
<PAGE>

                                      17

                                             By: /s/ Richard Nick
                                                --------------------------------
                                                Name: Richard Nick
                                                Title: Vice President

                                             PENNSYLVANIA GLASS SAND CORPORATION

                                             By: /s/ Richard Nick
                                                --------------------------------
                                                Name: Richard Nick
                                                Title: Vice President

                                             THE FULTON LAND AND TIMBER COMPANY

                                             By: /s/ Richard Nick
                                                --------------------------------
                                                Name: Richard Nick
                                                Title: Vice President

                                             OTTAWA SILICA COMPANY

                                             By:________________________________
                                                Name:
                                                Title:

                                             GEORGE F. PETTINOS, INC.

                                             By: /s/ Richard Nick
                                                --------------------------------
                                                Name: Richard Nick
                                                Title: Vice President

                                             ELLEN JAY, INC.

                                             By: /s/ Richard Nick
                                                --------------------------------
<PAGE>

                                      18

                                                 Name: Richard Nick
                                                 Title: Vice President

                                              U.S. SILICA COMPANY

                                              By: /s/ Richard Nick
                                                 -------------------------------
                                                 Name: Richard Nick
                                                 Title: Vice President

                                              BETTER MATERIALS CORPORATION

                                              By: /s/ Richard Nick
                                                 -------------------------------
                                                 Name: Richard Nick
                                                 Title: Vice President

                                              BMC TRUCKING, INC.

                                              By: /s/ Richard Nick
                                                 -------------------------------
                                                 Name: Richard Nick
                                                 Title: Vice President

                                              BUCKS COUNTY CRUSHED STONE COMPANY

                                              By: /s/ Richard Nick
                                                 -------------------------------
                                                 Name: Richard Nick
                                                 Title: Vice President

                                              CHIPPEWA FARMS CORPORATION

                                              By: /s/ Richard Nick
                                                 -------------------------------
                                                 Name: Richard Nick
<PAGE>

                                      19
                                               Title: Vice President

                                            SHORE STONE COMPANY, INC.

                                            By: /s/ Richard Nick
                                               ---------------------------------
                                               Name: Richard Nick
                                               Title: Vice President

                                            COMMERCIAL STONE CO., INC.

                                            By: /s/ Richard Nick
                                               ---------------------------------
                                               Name: Richard Nick
                                               Title: Vice President

                                            STONE MATERIALS COMPANY, LLC

                                            By: Better Minerals & Aggregates
                                             Company, as Manager

                                            By: /s/ Richard Nick
                                               ---------------------------------
                                               Name: Richard Nick
                                               Title: Vice President

                                            COMMERCIAL AGGREGATES TRANSPORTATION
                                            AND SALES, LLC

                                            By: Stone Materials Company, LLC, as
                                             Manager

                                            By: /s/ Richard Nick
                                               ---------------------------------
                                               Name: Richard Nick
                                               Title: Vice President
<PAGE>

                                      20

BANQUE NATIONALE DE PARIS,
as Agent

By: /s/ Paul Barnes
   ----------------------
Name:
Title: AVP
<PAGE>

                                   EXHIBITA
                                      to
                   Intellectual Property Security Agreement

          FORM OF INTELLECTUAL PROPERTY SECURITY AGREEMENT SUPPLEMENT

                                                        ________ ____, _________

Banque National de Paris, New York Branch,
  as Agent
499 Park Avenue
New York, New York 10022
Attention:

 Intellectual Property Security Agreement dated as of September 30, 1999 among
Better Minerals & Aggregates Company and additional grantors named therein, as
                                 Grantors, and
                      Banque Nationale de Paris, as Agent

Ladies and Gentlemen:

     Reference is made to the above-captioned Intellectual Property Security
Agreement (as amended, supplemented or otherwise modified from time to time, the
"Security Agreement").  Unless otherwise defined herein, terms defined in the
 ------------------
Security Agreement are used herein as therein defined.

     The undersigned hereby agrees, as of the date first above written, to
become a Grantor under the Security Agreement as if it were an original party
thereto and agrees that each reference in the Security Agreement to a "Grantor"
or the "Grantors" shall also mean and be a reference to the undersigned.

     The undersigned hereby assigns and pledges to the Agent for its benefit and
the ratable benefit of the Secured Parties and hereby grants to the Agent for
its benefit and the ratable benefit of the Secured Parties as collateral for the
Secured Obligations a pledge and assignment of, and a security interest in, all
of the right, title and interest of the undersigned in and to its Intellectual
Property Collateral, whether now owned or hereafter acquired.

     The undersigned has attached hereto supplements to Schedules I through IV
to the Security Agreement, and the undersigned hereby certifies that such
supplements have been
<PAGE>

prepared by the undersigned in substantially the form of the Schedules to the
Security Agreement and are accurate and complete as of the date first above
written.

     The undersigned hereby makes each representation and warranty set forth in
Section 4 of the Security Agreement as to itself and as to its Intellectual
Property Collateral to the same extent as each other Grantor and hereby agrees
to be bound as a Grantor by all of the terms and provisions of the Security
Agreement to the same extent as any other Grantor.

     This letter shall be governed by and construed in accordance with the laws
of the State of New York.

                                              Very truly yours,

                                              [NAME OF ADDITIONAL
                                                GRANTOR]

                                              By _______________________________
                                                 Name:
                                                 Title:
                                                 Address: