<PAGE>

                                                                    Exhibit 10.2

                                                                  EXECUTION COPY

                                WAIVER LETTER AND
                                 AMENDMENT NO. 7
                                       TO
                                 LOAN AGREEMENT

     This WAIVER LETTER AND AMENDMENT NO. 7 TO LOAN AGREEMENT (this "Agreement
and Amendment"), made as of June 13, 2003, among OGLEBAY NORTON COMPANY
("Borrower"), the banking institutions named in Schedule 1 to the Loan Agreement
(as hereinafter defined) (collectively, the "Banks" and individually, "Bank"),
KEYBANK NATIONAL ASSOCIATION, as administrative agent for the Banks ("Agent"),
BANK ONE, MICHIGAN (now known as Bank One, NA), as syndication agent
("Syndication Agent") and THE BANK OF NOVA SCOTIA, as documentation agent
("Documentation Agent"),

                                   WITNESSETH:

     WHEREAS, Borrower, the Banks, the Agent, the Syndication Agent and the
Documentation Agent have entered into that certain Loan Agreement, dated as of
April 3, 2000, and as subsequently amended by that certain Amendment No. 1 to
Loan Agreement and Waiver, dated as of June 30, 2001, Amendment No. 2 to Loan
Agreement and Waiver, dated as of November 9, 2001, Amendment No. 3 to Loan
Agreement, dated as of December 24, 2001, Amendment No. 4 to Loan Agreement,
dated as of October 23, 2002, Amendment No. 5 to Loan Agreement, dated as of
January 8, 2003, and Waiver Letter and Amendment No. 6 to Loan Agreement, dated
as of March 31, 2003 (as so amended from time to time, the "Loan Agreement"),
pursuant to which the Banks have made certain loans and other financial
accommodations available to Borrower;

     WHEREAS, Borrower has advised the Agent that Borrower may violate one or
more of the financial covenants contained in Section 5.7 of the Loan Agreement
(the "Financial Covenant Violations") for periods of determination occurring
prior to the Waiver Expiration Date (as defined below);

     WHEREAS, subject to the terms and conditions hereof, the Banks and the
Agent are willing to temporarily waive: (i) the Events of Default set forth in
Section 7.2 (the "Designated Events of Default") of the Loan Agreement which
will occur by reason of the Financial Covenant Violations and (ii) the exercise
of rights and remedies under the Loan Agreement with respect to such Designated
Events of Default; and

     WHEREAS, the parties also desire to amend certain provisions of the Loan
Agreement as set forth herein and the Banks which are signatories hereto
constitute the "Majority Banks" required to so amend the Loan Agreement pursuant
to Section 10.3 thereof;

     NOW, THEREFORE, in consideration of the mutual promises and agreements
contained herein and other good and valuable consideration, the receipt and
adequacy of which are hereby acknowledged, Borrower and the Banks do hereby
agree as follows:

1.  DEFINED TERMS.

     Each defined term used herein and not otherwise defined herein shall have
the meaning ascribed to such term in the Loan Agreement, as amended hereby.


<PAGE>

2.   AGREEMENT TO WAIVE.

      Notwithstanding the occurrence or continuation of the Designated Events of
Default, subject to satisfaction of the conditions precedent set forth in
Section 5 hereof, the Designated Events of Default are hereby waived in
accordance with the Loan Agreement from the date of occurrence thereof until the
Waiver Expiration Date and the Banks and Agent will not exercise rights and
remedies under the Loan Agreement and the other Loan Documents as a result of
the occurrence of such Designated Events of Default until after the Waiver
Expiration Date. Nothing contained in this Agreement and Amendment shall
prejudice any rights or remedies the Banks or the Agent may have, or the right
of the Banks and the Agent to exercise any such rights and remedies, prior to
the Waiver Expiration Date with respect to Events of Default (whether now
existing or hereafter occurring and including any violation of Section 5.7B of
the Loan Agreement) other than the Designated Events of Default. Moreover,
nothing contained in this Agreement and Amendment shall prejudice any rights or
remedies the Banks or the Agent may have, or the right of the Banks or the Agent
to exercise any such rights and remedies, with respect to any Events of Default
(including the Designated Events of Default) after the Waiver Expiration Date.

3.   AMENDMENT TO THE LOAN AGREEMENT.

      3.1 Amendment to Article I. Article I, Definitions, is amended by: (i)
adding thereto a new definition "Amendment No. 7 Closing Date," to be inserted
into Article I in appropriate alphabetical order to read as set forth below,
(ii) amending paragraph (a) of the definition of "Applicable Margin" and the
first clause of paragraph (b) of such definition to read as set forth below and
(iii) amending the definition of "Waiver Expiration Date" to read as set forth
below:

      "Amendment No. 7 Closing Date" shall mean the date on which the "Effective
Date" (as such term is defined in Section 5 of that certain Waiver Letter and
Amendment No. 7 to Loan Agreement, dated as of June 13, 2003) occurs.

      "Applicable Margin" shall mean:

          (a) for the period commencing on the Amendment No. 7 Closing Date
      until and including the Waiver Expiration Date, (i) four hundred fifty
      (450) basis points for each LIBOR Interest Segment, and (ii) two hundred
      twenty-five (225) basis points for the Prime Interest Segment, and . . .

          (b) commencing August 16, 2003, . . .

      "Waiver Expiration Date" means the earlier of: (i) August 15, 2003 or (ii)
July 31, 2003 (if the Borrower is unable by July 9, 2003 to obtain a waiver of
any Events of Default under the 2002 Senior Secured Fund Notes which waiver
extends until August 15, 2003 or later).

      3.2 Amendment to Section 5.3. Section 5.3 of the Loan Agreement is hereby
amended as follows: (w) with respect to the fiscal quarter ending June 30, 2003
only, paragraph (a) of Section 5.3 shall be amended so that the financial
statements with respect to such fiscal quarter shall be required to be released
to the public and delivered to each Bank on August 1, 2003 and such financial
statements with respect to such fiscal quarter (with any adjustments made to
such financial statements) shall be disclosed in the Borrower's 10Q and
delivered to each Bank by August 15, 2003, (x) with respect to the fiscal
quarter ending June 30, 2003 only, paragraph (c) of Section 5.3 shall be amended
so that the Borrower shall be required to deliver to

                        Amendment No. 7 to Loan Agreement

                                       2

<PAGE>

each Bank on August 1, 2003 calculations of the financial covenants set forth in
Section 5.7B (rather than Section 5.7) of the Loan Agreement which calculations
shall be based on the financial statements delivered to the Banks on August 1,
2003 and certified by a Financial Officer of the Borrower (subject to such
adjustments as are made to the financial statements included in the 10Q filed
for June 30, 2003), (y) with respect to the fiscal quarter ending June 30, 2003
only, paragraph (c) of Section 5.3 shall be further amended so that the Borrower
shall be required to deliver to each Bank on August 15, 2003 a Compliance
Certificate and calculations of the financial covenants set forth in Section
5.7B (rather than Section 5.7) of the Loan Agreement which calculations shall be
based on the financial statements delivered to the Banks on August 15, 2003 and
certified by a Financial Officer of the Borrower.

     3.3 Temporary Financial Covenants. In the event the Effective Date occurs,
then on and after June 16, 2003 until and including the Waiver Expiration Date,
Section 5 of the Loan Agreement shall be amended to add Section 5.7B thereto to
read as set forth below (the terms of Section 5.7 as in effect prior to this
Agreement and Amendment shall become again effective after the Waiver Expiration
Date):

     SECTION 5.7B TEMPORARY FINANCIAL COVENANTS

          (a) LEVERAGE RATIO. The Companies shall not suffer or permit at any
     time the Leverage Ratio to exceed 8.75 to 1.00 on June 16, 2003 through and
     including the Waiver Expiration Date.

          (b) SENIOR SECURED DEBT RATIO. The Companies shall not suffer or
     permit at any time the ratio of: (x) Total Senior Funded Indebtedness to
     the extent such Indebtedness is a secured obligation (but, excluding for
     purposes hereof, the Indebtedness evidenced by the 2002 Senior Secured Fund
     Notes) to (y) Consolidated Pro-Forma EBITDA to be greater than 5.25 to 1.00
     on June 16, 2003 through and including the Waiver Expiration Date, based
     upon the financial statements of the Companies for the most recently
     completed four (4) fiscal quarters.

          (c) INTEREST COVERAGE. The Companies shall not suffer or permit at any
     time the ratio of: (x) Consolidated Pro-Forma EBITDA to (y) Consolidated
     Pro-Forma Interest Expense (less non cash amortized financing and FAS 133
     costs to the extent included in Consolidated Pro-Forma Interest Expense in
     accordance with GAAP) to be less than 1.15 to 1.00 on June 16, 2003 through
     and including the Waiver Expiration Date, based upon the financial
     statements of the Companies for the most recently completed four (4) fiscal
     quarters.

          (d) CASH-FLOW COVERAGE. The Companies shall not suffer or permit at
     any time the ratio of: (x) Consolidated Pro-Forma Cash Flow to (y)
     Consolidated Pro-Forma Fixed Charges (excluding from Pro-Forma Fixed
     Charges for purposes of calculating compliance with this covenant, amounts
     payable with respect to the Revolving Loans (as defined in the Credit
     Agreement) and the Term Loans to be less than 0.60 to 1.00 on June 16, 2003
     through and including the Waiver Expiration Date, based upon the financial
     statements of the Companies for the most recently completed four (4) fiscal
     quarters.

          (e) NET WORTH. The Companies shall not suffer or permit Consolidated
     Net Worth at any time, based upon the Consolidated financial statements of
     the

                        Amendment No. 7 to Loan Agreement

                                       3

<PAGE>

     Companies for the most recently completed fiscal quarter, to fall below the
     current minimum amount required, which current minimum amount required
     shall be as of June 30, 2003, an amount equal to $87,678,000; provided,
     however, that (i) any non-cash impact to Consolidated Net Worth related to
     FAS 142 shall be excluded in calculating Borrower's compliance with this
     covenant and (ii) any potential non-cash impact associated with the
     extinguishment of Indebtedness (as a result of the issuance of the 2002
     Senior Secured Fund Notes and the required repayment of a portion of the
     Revolving Credit Loans) as indicated pursuant to EITF 96.19/SFAS 140 shall
     likewise be excluded in calculating Borrower's compliance with this
     covenant.

          (f) MINIMUM CONSOLIDATED PRO-FORMA EBITDA. The Companies shall not
     suffer or permit at any time Consolidated Pro-Forma EBITDA to be less than
     $51,500,000 on June 16, 2003 through and including the Waiver Expiration
     Date, based upon the financial statements of the Companies for the most
     recently completed four (4) fiscal quarters.

     3.4  Addition to Section 5.24. 2003, Section 5.24 of Article V is amended
by adding the following sentence at the end of such Section:

     In the event that Borrower agrees to any increase in existing interest rate
     or fees, or the creation or increase of penalty or premium, or the granting
     of any other right or chose having economic value with respect to any
     contract or agreement for the borrowing of money in excess of Two Million
     Dollars ($2,000,000) and, notwithstanding the amount thereof, the 2002
     Senior Secured Fund Notes, the Indenture, and any loans or capital leases
     for the purchase or lease of assets extended by US Bank National
     Association or National City Bank or their affiliates then: (i) with
     respect to any such increase in existing interest or fees, the Banks shall
     receive the same increase in any existing interest rate and fees or (ii)
     with respect to any such creation, increase or grant of a penalty or
     premium or any other right or chose having economic value, the Banks shall
     receive an amount equal to (x) the Debt owed to the Banks hereunder
     multiplied by (y) a percentage equal to (A) the aggregate amount or value
     of such penalty, premium, right or chose divided by (B) the of aggregate
     outstanding amount of such contract or agreement for borrowed money.

     3.5  Addition of Section 5.32. Article V is amended by adding Section 5.32
thereto to read as follows:

          SECTION 5.32. APPRAISALS. Borrower shall: (i) use its best efforts to
     furnish to Agent no later than July 15, 2003 final versions of each Haas
     appraisal of each of the Companies' material mineral and mining operations
     (other than with respect to Special Minerals Velarde and Kings Mountain
     operations, in form and substance acceptable to Agent and (ii) use its best
     efforts to furnish to Agent no later than July 31, 2003 final versions of
     the Haas appraisal of Special Minerals Velarde and Kings Mountain
     operations, in form and substance acceptable to Agent.

     3.6  Addition of Section 5.33. Article V is amended by adding Section 5.33
thereto to read as follows:

          SECTION 5.33. FINAL OFFERING MEMORANDA. Borrower shall furnish to
     Agent true and complete copies of each final offering memoranda generated
     with respect to any proposed sale of any of the Companies' assets as soon
     as they are completed by

                        Amendment No. 7 to Loan Agreement

                                       4

<PAGE>

     Borrower's investment banker Harris Williams. Borrower shall also furnish
     to Agent: (i) relevant industry information and resumes by no later than
     July 9, 2003 and (ii) relevant valuation reports and estimated time
     schedules for closing such contemplated sales of assets of the Companies by
     no later than July 15, 2003.

     3.7 Amendment to Section 7.2. Section 7.2 of the Loan Agreement is hereby
amended to add therein a reference to "5.7B" after the reference to "5.7" and
"5.7A".

4.  REPRESENTATIONS AND WARRANTIES.

     Borrower hereby represents and warrants as follows:

     4.1 The Agreement and Amendment. This Agreement and Amendment has been duly
and validly executed by an authorized executive officer of Borrower and
constitutes the legal, valid and binding obligation of Borrower enforceable
against Borrower in accordance with its terms. The execution, delivery, and
performance of this Agreement and Amendment, the Loan Agreement (as amended
hereby), and the other Loan Documents to which Borrower is a party are within
Borrower's corporate powers, have been duly authorized, and are not in
contravention of law or the terms of Borrower's Certificate of Incorporation or
By-Laws or any indenture (including the Indenture) or other document or
instrument evidencing borrowed money or any other agreement or undertaking to
which Borrower is a party or by which it or its property is bound.

     4.2 Claims and Defenses. As of the date of this Agreement and Amendment,
neither Borrower nor any of the Companies has any defenses, claims,
counterclaims or setoffs with respect to the Loan Agreement, the Loan Documents
or any obligations thereunder or with respect to any actions of Agent, the
Syndication Agent, the Documentation Agent, the Banks or any of their respective
officers, directors, shareholders, employees, agents or attorneys, and Borrower
irrevocably and absolutely waives any such defenses, claims, counterclaims and
setoffs and releases Agent, the Syndication Agent, the Documentation Agent, the
Banks, and each of their respective officers, directors, shareholders,
employees, agents and attorneys, from the same.

     4.3 Loan Agreement; Status of Loan Agreement. The Loan Agreement, as
amended by this Agreement and Amendment, remains in full force and effect and
remains the valid and binding obligation of Borrower enforceable against
Borrower in accordance with its terms except as expressly limited hereby. As of
the date of this Agreement and Amendment, the representations and warranties of
Borrower set forth in the Loan Agreement are true and correct in all material
respects with the same force and effect as if made on and as of such date except
to the extent that any thereof expressly relate to an earlier date.

     4.4 Nonwaiver. The execution, delivery, performance and effectiveness of
this Agreement and Amendment shall not, except as provided in Article 2 of this
Agreement and Amendment, operate as, be deemed to be, or be construed to be a
waiver: (i) of any right, power or remedy of Agent, the Syndication Agent, the
Documentation Agent, or any Bank under the Loan Agreement or (ii) of any term,
provision, representation, warranty or covenant contained in the Loan Agreement
or any other documentation executed in connection therewith. Further, except as
provided in Article 2 of this Agreement and Amendment, none of the provisions of
this Agreement and Amendment shall constitute, be deemed to be or construed to
be: (i) a waiver of any Event of Default under the Loan Agreement as previously
amended and as further amended

                        Amendment No. 7 to Loan Agreement

                                       5

<PAGE>

by this Agreement and Amendment or (ii) a revocation of any prior written
waivers of any Events of Default thereunder.

     4.5 Reference to and Effect on the Loan Agreement. Upon the effectiveness
of this Agreement and Amendment, each reference in the Loan Agreement to "this
Agreement," "hereunder," "hereof," "herein," or words of like import shall mean
and be a reference to the Loan Agreement, as previously amended and as further
amended hereby, and each reference to the Loan Agreement in any other document,
instrument or agreement executed and/or delivered in connection with the Loan
Agreement shall mean and be a reference to the Loan Agreement, as previously
amended and as further amended hereby.

5.  CONDITIONS PRECEDENT TO EFFECTIVENESS OF THIS AGREEMENT AND AMENDMENT.

     This Agreement and Amendment shall become effective as of the time (the
"Effective Date") on which each of the following conditions precedent shall have
been fulfilled:

     5.1 Waiver Letter and Amendment No. 7 to Loan Agreement. Agent shall have
received from Borrower and Banks constituting the Majority Banks (as determined
by the Agent) an original counterpart of this Agreement and Amendment, executed
and delivered by a duly authorized officer of Borrower and each such Bank, as
the case may be.

     5.2 Waiver Letter and Amendment No. 7 to Credit Agreement. Agent shall have
received from Borrower and Banks constituting Majority Banks (as determined by
the Agent) an original counterpart of the Waiver Letter and Amendment No. 7 to
Credit Agreement, in form and substance acceptable to Agent, executed and
delivered by a duly authorized officer of Borrower and each such Bank, as the
case may be.

     5.3 Acknowledgment of Guarantors. Agent shall have received the
Acknowledgment of Guarantors, attached hereto, executed and delivered by a duly
authorized officer of each of the Guarantors.

     5.4 Agreement and Amendment Fee; Legal Expenses to Date. Agent shall have
received, for the benefit of each Bank (including Agent in its capacity as a
Bank) approving and executing this Agreement and Amendment, a one time fee in
the amount of ten (10) basis points multiplied by the Term Loan Commitment
Amount of such Bank. In addition, Agent shall have received payment of all
currently outstanding expenses of Agent incurred in connection with outstanding
fees and expenses of counsel to Agent in connection with the matters
contemplated hereby or undertaken to date in connection with the Credit
Agreement and Loan Agreement.

     5.5 Opinion Concerning Agreement and Amendment. Agent shall have received
an opinion of counsel to Borrower and its subsidiaries, in form and substance
satisfactory to Agent, as to the authorization, due execution and delivery, and
enforceability by and against Borrower and the Subsidiaries thereof which are
parties to this Agreement and Amendment.

     5.6 Other Deliveries. Agent shall have received from Borrower any other
agreements previously discussed as being required in connection with this
Amendment , in form and substance acceptable to Agent, executed and delivered by
a duly authorized officer of Borrower.

                        Amendment No. 7 to Loan Agreement

                                       6

<PAGE>

6.  MISCELLANEOUS.

     6.1 Governing Law. This Agreement and Amendment has been delivered and
accepted at and shall be deemed to have been made at Cleveland, Ohio. This
Agreement and Amendment shall be interpreted and the rights and liabilities of
the parties hereto determined in accordance with the laws of the State of Ohio,
without regard to principles of conflict of law, and all other laws of mandatory
application.

     6.2 Severability. Each provision of this Agreement and Amendment shall be
interpreted in such manner as to be valid under applicable law, but if any
provision hereof shall be invalid under applicable law, such provision shall be
ineffective to the extent of such invalidity, without invalidating the remainder
of such provision or the remaining provisions hereof.

     6.3 Counterparts. This Agreement and Amendment may be executed in one or
more counterparts, each of which, when taken together, shall constitute but one
and the same agreement.

                           [Signature Page to Follow]

                        Amendment No. 7 to Loan Agreement

                                       7

<PAGE>

         IN WITNESS WHEREOF, Borrower has caused this Waiver Letter and
Amendment No. 7 to Loan Agreement to be duly executed and delivered by its duly
authorized officer as of the date first above written.

Address:    North Point Tower                   OGLEBAY NORTON COMPANY
            1001 Lakeside Avenue,               By:_____________________________
            15th floor                          Name:  Julie A. Boland
                                                     ---------------------------
            Cleveland, Ohio 44114-1151          Title: Chief Financial Officer
                                                      --------------------------
            Attention: Treasurer


Address:    Key Center                          KEYBANK NATIONAL ASSOCIATION,
            127 Public Square                   as a Bank and as Agent
            Cleveland, Ohio 44114-1306          By:_____________________________
            Attention: Large Corporate          Name:  Thomas J. Purcell
                                                     ---------------------------
            Banking Division                    Title: Sr. Vice President
                                                      --------------------------


Address:    611 Woodward Avenue                 BANK ONE, NA (formerly known as
            Detroit, Michigan 48226             Bank One, Michigan)
            Attention: Large Corporate          By:_____________________________
            Banking Division                    Name:___________________________
                                                Title:__________________________


Address:    600 Peachtree Street                THE BANK OF NOVA SCOTIA
            Suite 2700
            Atlanta, Georgia 30308              By:_____________________________
            Attention: Large Corporate          Name:___________________________
            Banking Division                    Title:__________________________

                        Amendment No. 7 to Loan Agreement

                                       S-1

<PAGE>

Address:    500 Woodward Avenue, 9th Fl.        COMERICA BANK
            Detroit, Michigan 48226
            Attention: Large Corporate          By:_____________________________
            Banking Division                    Name:___________________________
                                                Title:__________________________


Address:    231 S. LaSalle Street               BANK OF AMERICA, N.A.
            Chicago, Illinois 60697
            Attention: Ronald A. Prince         By:_____________________________
            Banking Division                    Name:___________________________
                                                Title:__________________________


Address:    111 West Monroe, 10W                HARRIS TRUST AND SAVINGS BANK
            Chicago, Illinois 60603
            Attention: Large Corporate          By:_____________________________
            Banking Division                    Name:___________________________
                                                Title:__________________________


Address:    ___________________                 GOLDMAN SACHS CREDIT
                                                PARTNERS LP II
            ___________________
            ___________________                 By:_____________________________
            ___________________                 Name:___________________________
                                                Title:__________________________


Address:    6 High Ridge Park                   GE CAPITAL CFE, INC.
            Building 6 C, Mail Stop 4097-203
            Stamford, Ct., 06927-5100           By:_____________________________
            Attention: Commercial Finance       Name:___________________________
                                                Title:__________________________


Address:    1900 East Ninth Street              NATIONAL CITY BANK
            Cleveland, Ohio 44114
            Attention: Large Corporate          By:_____________________________
            Banking Division                    Name:___________________________
                                                Title:__________________________


Address:    250 West Huron                      JPMORGAN CHASE BANK
            Cleveland, Ohio 44113
            Attention: Large Corporate          By:_____________________________
            Banking Division                    Name:___________________________
                                                Title:__________________________

                        Amendment No. 7 to Loan Agreement

                                       S-2

<PAGE>

Address:    1404 East Ninth Street              FIFTH THIRD BANK
            Cleveland, Ohio 44114
            Attention: Large Corporate          By:_____________________________
            Banking Division                    Name:___________________________
                                                Title:__________________________


Address:    1350 Euclid Avenue                  U. S. BANK, NATIONAL
                                                ASSOCIATION
            Cleveland, Ohio                     (f\k\a Firstar Bank National
                                                Association)
            Attention: Commercial               By:_____________________________
            Banking Division                    Name:___________________________
                                                Title:__________________________


Address:    ________________________            _________________________
            ________________________
            ________________________            By: GRANDVIEW CAPITAL
                                                MANAGEMENT, LLC
                                                Name:___________________________
                                                Title:__________________________


Address:    110 South Stratford Road            BRANCH BANKING & TRUST CO.
            Suite 301
            Winston-Salem, NC 27104             By:_____________________________
            Attention: Large Corporate          Name:___________________________
            Banking Division                    Title:__________________________


Address:    ________________________            _________________________
            ________________________
            ________________________            By:_____________________________
            ________________________            Name:___________________________
                                                Title:__________________________


Address:    ________________________            _________________________
            ________________________
            ________________________            By:_____________________________
            ________________________            Name:___________________________
                                                Title:__________________________

                        Amendment No. 7 to Loan Agreement

                                       S-3

<PAGE>

Address:    ________________________            _________________________
            ________________________
            ________________________            By:_____________________________
            ________________________            Name:___________________________
                                                Title:__________________________

                        Amendment No. 7 to Loan Agreement

                                       S-4

<PAGE>

                          ACKNOWLEDGMENT OF GUARANTORS

         Each of the undersigned consents and agrees to and acknowledges the
terms of the foregoing Waiver Letter and Amendment No. 7 to Loan Agreement as of
the date first above written. Each of the undersigned further agrees that the
obligations of each of the undersigned pursuant to the Guaranty of Payment, the
Security Agreement and any other Loan Document to which any of the undersigned
is a party shall remain in full force and effect and be unaffected hereby.

                               ONCO Investment Company
                               Oglebay Norton Management Company
                               Oglebay Norton Industrial Sands, Inc.
                               Oglebay Norton Terminals, Inc.
                               Oglebay Norton Engineered Materials, Inc.
                               Michigan Limestone Operations, Inc.
                               Global Stone Corporation (successor by merger to
                                        Oglebay Norton Acquisition Company)
                               Global Stone Tenn Lutrell Company
                               Global Stone Chemstone Corporation
                               Global Stone St. Clair, Inc.
                               Global Stone Management Company
                               Global Stone Filler Products Company
                               Global Stone James River, Inc.
                               GS PC, Inc.
                               Oglebay Norton Minerals, Inc.
                               Oglebay Norton Specialty Minerals, Inc.
                               ON Coast Petroleum Company
                               ON Marine Services Company
                               ONCO WVA, Inc.
                               ONTEX, Inc.
                               Saginaw Mining Company
                               Erie Navigation Company
                               Erie Sand and Gravel Company
                               Erie Sand Steamship Co.
                               Mountfort Terminal, Ltd.
                               Serve-All Concrete, Inc.
                               S & J Trucking, Inc.

                               By: ___________________________________________
                                     Rochelle F. Walk, as Vice President and
                                     Secretary of each of the companies listed
                                     above.

                               Texas Mining, LP, by its General Partner
                               ONTEX, Inc.

                                     By: ______________________________________
                                              Rochelle F. Walk
                                              Vice President and Secretary

                        Amendment No. 7 to Loan Agreement

                                       S-5

<PAGE>

                               Global Stone PenRoc, LP, by its General Partner,
                               GS PC, Inc,.

                                     By: ______________________________________
                                              Rochelle F. Walk,
                                              Vice President and Secretary

                               Oglebay Norton Marine Services Company, L.L.C.,
                               by its Member ON Marine Services Company

                                     By: _________________________________
                                              Rochelle F. Walk
                                              Vice President and Secretary

                               Oglebay Norton Marine Management Company, LLC. by
                               its member Oglebay Norton Marine Services Company

                                     By: _________________________________
                                              Rochelle F. Walk
                                              Vice President and Secretary

                               Global Stone Portage, LLC by its member
                               ___________________________

                                     By: _________________________________
                                              Rochelle F. Walk
                                              Vice President and Secretary

                        Amendment No. 7 to Loan Agreement

                                       S-6