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                                                                   EXHIBIT 10.73


                           PURCHASE AND SALE AGREEMENT

         THIS AGREEMENT, effective as of the 1st day of June 2000, is made and
entered into by and between ELISA A. STONER, as Seller ("SELLER"), and TIPPERARY
CORPORATION as Buyer ("BUYER").

         1. Basis of Agreement. SELLER, BUYER's subsidiary, Tipperary Oil & Gas
(Australia) Pty Ltd, and others, are non-operators under that certain Joint
Operating Agreement dated May 15, 1992 between non-operators and Tri-Star
Petroleum Company, as Operator (the "Operating Agreement"), relative to the
development of the coalbed methane gas project known as the Comet Ridge Project,
located in the State of Queensland, Australia. The Operating Agreement is
attached hereto respectively as Exhibit "A." SELLER desires to sell all of her
interest in the contractual and other rights, title and interest, of any nature
whatsoever, arising under or created by the Operating Agreement, including,
without limitation, all contract rights and all undivided interest in any real
or personal property which SELLER owns or has the right to acquire under the
terms of the Operating Agreement presently or in the future, and BUYER desires
to purchase all of SELLER's contractual and other rights, title and interest of
any nature whatsoever arising under or created by the Operating Agreement,
including, without limitation, all contract or other rights of any nature and
any undivided interest in any real or personal property which SELLER owns or has
the right to acquire under the Operating Agreement presently or in the future,
all in accordance with the terms and conditions of this Purchase and Sale
Agreement (the "Agreement").

         2. Assets to be Purchased and Sold. Subject to the terms set forth in
this Agreement, and the terms and conditions of the Operating Agreement, SELLER
agrees to sell to BUYER and BUYER agrees to buy all of SELLER's undivided
interest in the assets and properties hereinafter described, as follows:


<TABLE>
<CAPTION>
                                      A.                     B.                            C.
                                                        In Leasehold                 In Acquisition,
                                      In              Ownership & Lease          Drilling, Development,
                                  Production         Operating Expenses         Workover & Capital Costs
                                     (%)                     (%)                           (%)
<S>                               <C>                <C>                        <C>
Before Project Payout              1.012500                1.12500                        1.00

After Project Payout               1.260000                1.40000                        1.40
</TABLE>


            (a) SELLER's undivided interest, if any, in and to, and/or SELLER's
            right to acquire undivided interests in and to the Authority to
            Prospect 526 attached as Exhibit "B" hereto, and the Authorities to
            Prospect (which preceded Authority to Prospect 526) attached as
            Exhibit "B" to the Operating


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            Agreement, and any extension, renewal or replacement of any
            Authority to Prospect, howsoever denominated (collectively the
            "ATP");

            (b) SELLER's rights, if any, to reacquire any acreage which had
            comprised a part of the ATP but was relinquished by the Operator as
            a part of, or in connection with, a scheduled contraction of the
            ATP, and/or any other acreage which was at any time a part of the
            ATP but lapsed or was relinquished for any reason;

            (c) SELLER's undivided interest, if any, in and to, and SELLER's
            right to acquire undivided interests in and to the petroleum leases
            and applications for petroleum leases listed and described on
            Exhibit "C" attached hereto (the "Leases");

            (d) SELLER's undivided interest, if any, in and to, and SELLER's
            right to acquire undivided interests in and to Pipeline License No.
            27 described on Exhibit "D" and attached hereto and any connecting
            pipeline and/or gas gathering systems;

            (e) SELLER's undivided interest, if any, in and to, and SELLER's
            right to acquire undivided interests in and to all permits,
            licenses, leases, servitudes, rights-of-way, easements, pipeline
            licenses and any other tenements or similar rights associated with
            the ATP and Leases and the operation of the ATP and Leases, whether
            specifically enumerated herein and whether presently existing,
            applied for, pending, created, issued or accrued, or applied for,
            created, issued or accrued in the future;

            (f) SELLER's undivided interest, if any, in and to, and SELLER's
            right to acquire undivided interests in and to the wells listed and
            described on Exhibit "E" (the "Wells") attached hereto, including
            all formations and depths within or below the wellbore, whether or
            not presently productive;

            (g) SELLER's right, if any, to acquire an interest in any wells to
            be drilled in the future on the acreage covered by the ATP and
            Leases, or any extension, renewal or replacement of the ATP,
            howsoever denominated;

            (h) SELLER's undivided interest, if any, in and to, and SELLER's
            right to acquire undivided interests in and to, all personal and
            mixed property located on the lands covered by the ATP and Leases
            and used in operations conducted on same, whether located on or off
            the wellsites, the Leases or the acreage described by the ATP;

            (i) SELLER's undivided interest in and to, and the right to acquire
            undivided interests in and to, any and all gas purchase and sale
            agreements, crude purchase and sale agreements, gas pipeline
            agreements, volumetric or


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<PAGE>   3


            other production payments of any nature, leases of equipment or
            facilities and any and all other agreements and rights which are (i)
            appurtenant to the ATP, Leases or Wells, or (ii) used or held for
            use in connection with the ownership or operation of the Wells or
            with the production, treatment, sale or disposal of water,
            hydrocarbons, or associated substances produced, used or disposed of
            in connection with the Wells, ATP or the Leases;

            (j) To the extent that such may be lawfully transferred, all of
            SELLER's tax benefits or tax deductions under the laws of Australia,
            the State of Queensland or any municipality thereof, whether or not
            presently accrued, owned by or vested in SELLER, including, without
            limitation, any tax benefits or deductions which may be lawfully
            transferred to BUYER under Australia's Income Tax Assessment Act
            1997, or any applicable predecessor to such Act. This shall be a
            continuing obligation;

            (k) All of SELLER's right or rights to enforce its contract rights,
            title, interests of any nature, covenants, representations,
            warranties or other rights of any nature, if any, which SELLER is or
            may in the future be entitled to enforce against SELLER's
            predecessors-in-title;

            (l) All of SELLER's right, title and interest, if any, under any
            Deed or Deeds of Confirmation of Producing License executed by
            Tri-Star Petroleum Company in favor of SELLER, as Drilling
            Participant;

            (m) All of SELLER's right, title and interest, if any, under any
            Deed or Deeds of Charge executed by Tri-Star Petroleum Company in
            favor of SELLER, as Chargeholder;

            (n) All of SELLER's rights, titles and interests in and to the
            Operating Agreement including, without limitation, access to the
            Contract Area and information, accruing or attributable to SELLER's
            interest, acreage or cash contributions, bonds and insurance
            policies, hydrocarbon marketing rights (including, without
            limitation, rights accruing under the gas balancing agreement
            attached as Exhibit E to the Operating Agreement), participation
            rights, producing units, records, severed production, voting rights
            and any and all other rights under the Operating Agreement of any
            nature whatsoever, whether express or implied, whether presently
            existing or vested in SELLER or arising in the future, whether
            specifically enumerated above, including, but not limited to, all
            choses-in-action.

The rights and interests described in paragraphs (a) through (n) above are
collectively referred to in this Agreement as the "Assets."


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         3. The Effective Date. The effective date of the purchase and sale, for
all purposes, shall be the 1st day of June, 2000 at 12:01 a.m., Greenwich Mean
Time plus ten, local time, Brisbane, Australia ("Effective Date").


         4. Purchase Price and Closing Date. The purchase price for the Assets
shall be one million fifty thousand dollars and no cents ($1,050,000) payable
entirely with 300,000 shares of BUYER'S common stock, which shall have an agreed
value of $3.50 per share for purposes of this Agreement. The sale shall be
completed as mutually agreed upon by BUYER and SELLER on or before thirty (30)
days from the date of the execution of this agreement by both BUYER and SELLER
(the "Closing Date"). At the closing, SELLER shall deliver to BUYER a fully
executed assignment and conveyance in the form attached hereto as Exhibit "F."
The purchase price shall be paid to SELLER with a stock certificate representing
300,000 shares of BUYER's common stock as of the Closing Date, without regard to
any increase or decrease in the market value of BUYER's common stock between the
Effective Date and the Closing Date.

         5. Registration Rights Agreement. SELLER shall, as of the Closing Date,
enter into a Registration Rights Agreement in the form attached hereto as
Exhibit "G."

         6. Post-Closing Adjustments. On or before sixty (60) days after the
Closing Date, BUYER and SELLER shall undertake to agree with respect to the
adjustments or payments that were not fully and finally determined as of the
Closing Date, and the amount due from BUYER to SELLER, or SELLER to BUYER, as
the case may be. SELLER shall provide BUYER access to such of SELLER's records
as may be reasonably necessary to a determination of post-closing adjustments.
Payment by BUYER or SELLER shall be made in immediately available funds within
thirty (30) business days of agreement. If the post-closing adjustment has not
been agreed upon within the time period set forth herein, either party may seek
to enforce any rights it claims hereunder.

         7. Mutual Representations and Warranties. BUYER and SELLER each
represents and warrants to the other that:

            (a) Each has all approvals, authority and power necessary to enter
            into this Agreement and to perform (or cause to be performed) all of
            the obligations and transactions contemplated hereunder;

            (b) The execution, delivery and performance of this Agreement, and
            the obligations and transactions contemplated hereby, will not:

                (i) violate or conflict with any provision of any Certificate of
                Incorporation, corporate by-laws, partnership agreement or
                limited partnership agreement or other governing document of any
                nature as may be applicable to either of them;


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                (ii) result in the breach of any term or condition of, or
                constitute a default or cause the acceleration of any obligation
                under any agreement or instrument to which either of them is a
                party or is bound;

                (iii) violate or conflict with any judgment, decree, order,
                permit, law, rule or regulation, relating to this Agreement, the
                Assets, or either of them under Applicable laws.

            (c) This Agreement has been duly executed and delivered, and at the
            closing all documents and instruments required hereunder will have
            been duly executed and delivered, on behalf of each of the persons
            executing this Agreement. This Agreement, and all such documents and
            instruments shall constitute legal, valid and binding obligations
            enforceable in accordance with their respective terms, except to the
            extent enforceability may be impacted by bankruptcy, reorganization,
            insolvency or similar laws affecting creditors rights generally;

            (d) No legal or administrative proceeding in or of the United States
            of America is pending or threatened that would prohibit it from
            entering into or consummating this Agreement; and

            (e) Each of the representations made by BUYER and SELLER herein
            shall be true and correct as of the Effective Date and the Closing
            Date with the same force and effect as if separately made on each of
            those dates.

         8. Seller's Representations and Warranties. SELLER hereby represents
and warrants to BUYER and agrees that:

            (a) SELLER will convey, assign and transfer to BUYER its contract,
            property and other rights in the Assets. The Assets constitute the
            Seller's sole and separate marital property under the laws of the
            State of Texas and, without limiting the generality of the
            representations and warranties in Paragraph 7 above, it is
            unnecessary for SELLER's husband to execute this Agreement, or the
            Assignment attached hereto as Exhibit F, to complete the transfer of
            the Assets from SELLER to BUYER contemplated hereby, as set forth in
            paragraph 2. above;

            (b) There is no action, suit, proceeding, claim or investigation by
            any persons, entities, administrative agency or governmental body
            pending or threatened against SELLER that may adversely affect
            SELLER's title, and the ability to transfer the Assets to BUYER;


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<PAGE>   6


            (c) SELLER will, for herself, her successors and assigns, warrant
            and defend the title of BUYER, its successors and assigns to the
            Assets, interests and properties against every person whomsoever
            claiming the same or any party thereof by, through and under SELLER,
            but not otherwise; however WITH RESPECT TO THE WELLS, EQUIPMENT AND
            OTHER ITEMS OF PERSONALTY WHICH MAY BE COVERED HEREBY, THE SAME ARE
            USED AND ARE SOLD ON AN "AS IS" AND "WHERE IS" BASIS WITH ALL
            FAULTS, IF ANY. SELLER SHALL HAVE NO LIABILITY TO BUYER FOR ANY
            CLAIMS, LOSS, OR DAMAGE CAUSED OR ALLEGED TO BE CAUSED DIRECTLY OR
            INDIRECTLY, INCIDENTALLY OR CONSEQUENTIALLY BY SAID WELLS, EQUIPMENT
            OR PERSONAL PROPERTY, BY ANY INADEQUACY THEREOF OR THEREWITH,
            ARISING IN STRICT LIABILITY OR OTHERWISE, OR IN ANY WAY RELATED TO
            OR ARISING OUT OF THIS AGREEMENT. SELLER MAKES NO EXPRESS OR IMPLIED
            WARRANTIES OF ANY KIND, INCLUDING THOSE OF MERCHANTABILITY AND
            FITNESS FOR A PARTICULAR PURPOSE WITH RESPECT TO SAID WELLS,
            EQUIPMENT AND PERSONAL PROPERTY AND EXPRESSLY DISCLAIMS ANY
            WARRANTIES WITH RESPECT THERETO;

            (d) The undivided interests in the Assets which BUYER shall receive
            shall include production or the right to proceeds of production from
            each Well located on the ATP and the Leases in an amount which is
            not less than the percentage net revenue interest set forth in
            Paragraph 2, Column A, above. In addition, SELLER represents that
            the undivided interests in the Assets which BUYER shall receive
            shall not require BUYER to bear a greater percentage of costs and
            expenses than the percentage interest set forth in paragraph 2,
            Column B or Column C, as applicable, above. This representation of
            warranty is by, through and under SELLER, but not otherwise;

            (e) To the extent of the interest described in paragraph 2, above,
            SELLER has full and complete ownership of the Assets conveyed,
            assigned and transferred hereunder, and that the Assets to be
            purchased by BUYER are free and clear of all liens, judgments,
            mortgages and other burdens or encumbrances created by SELLER;

            (f) SELLER's contract rights and/or title to undivided interest in
            the Assets has not been forfeited under the terms of the Operating
            Agreement covering the interests and SELLER has not been notified of
            any forfeiture or impending forfeiture of any interest under the
            Operating Agreement;

            (g) Any credit to the Operating Agreement, resulting from any audit
            of the joint account, any production imbalance or any judicial
            action or


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            determination attributable to SELLER's undivided interests in the
            Assets, shall accrue to the benefit of BUYER without regard to
            whether the credit relates to periods of time before or after the
            Effective Date;

            (h) Upon request by BUYER, SELLER will execute and return to BUYER a
            Notice under the Income Tax Assessment Act of 1997 as amended,
            section 330-235, formerly a 124AB Notice under Australia's Income
            Assessment Act;

            (i) SELLER has paid and discharged all invoices and joint interest
            billings from Operator, and SELLER is not in arrears on any amounts
            or charges of any nature related to the Assets; and

            (j) SELLER acknowledges that as of January 1999, the requisite
            percentage of interest in ownership under the Operating Agreement
            and the requisite number of non-operators voted to remove Tri-Star
            Petroleum Company as operator and to appoint Tipperary Oil & Gas
            (Australia) Pty Ltd as successor operator under the Operating
            Agreement.

         9. Additional Warranties and Representations of SELLER With respect to
the purchase price, as described above, to be paid in common shares of stock of
BUYER, SELLER makes the following additional warranties, representations and
agreements:

            (a) SELLER is an "Accredited Investor" as that term is defined in
            Rule 501(a) of Regulation D promulgated by the Securities Exchange
            Commission. A copy of Rule 501 of Regulation D has been provided to
            SELLER.

            (b) SELLER has had access to information and materials concerning
            BUYER and its business, operations, structuring and financing,
            including its Annual Report on Form 10-K for the Fiscal Year Ended
            September 30, 1999, Quarterly Reports on Form 10-Q for the quarters
            ended December 31, 1999 and March 31, 2000, and its definitive proxy
            statement relating to its Annual Meeting of Shareholders held on
            January 25, 2000. SELLER understands that BUYER faces several risks
            in its business as well as risks faced by the oil and gas business
            and risks described in the Form 10-K or incorporated therein by
            reference. All information requested by SELLER from BUYER or its
            representatives concerning BUYER and the terms and conditions of
            this Agreement has been made available to SELLER's satisfaction.
            SELLER has had the opportunity to ask questions of and receive
            answers from management of BUYER concerning BUYER and the terms and
            conditions of this Agreement, and to obtain from BUYER any
            additional information which BUYER possesses or can acquire without


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<PAGE>   8


            unreasonable effort or expense that is necessary to verify the
            accuracy of the information provided to SELLER.

            (c) Any shares of BUYER acquired by SELLER hereunder are for
            SELLER'S own account and not for or on behalf of any other person or
            entity.

            (d) If any shares of BUYER are acquired hereunder, no shares will be
            acquired with a view towards the distribution or redistribution with
            the intent to divide SELLER's participation with others.

            (e) SELLER will only resell any shares acquired under this agreement
            pursuant to registration under the Act and the laws of any
            applicable states or pursuant to an exemption from registration. The
            only registration rights to which SELLER has with respect to any
            shares acquired hereunder are as set forth in the Registration
            Rights Agreement attached hereto as Exhibit "G."

            (f) The stock certificates representing the shares of BUYER will
            bear a legend substantially as follows:

                The shares represented by this Certificate have not been
                registered under the Securities Act of 1933 (the "Act") and are
                "restricted securities" as that term is defined in Rule 144
                under the Act. The shares may not be offered for sale, sold or
                otherwise transferred except pursuant to an effective
                registration statement under the Act or pursuant to an exemption
                from registration under the Act, the availability which is to be
                established to the satisfaction of the Company.

            (g) With respect to any common shares of BUYER received by SELLER
            hereunder, and prior to any proposed sale, assignment, transfer or
            pledge of the shares (other than transfers not involving a change in
            beneficial ownership), unless there is in effect a registration
            statement under the Act covering the proposed transfer, SELLER shall
            give written notice to BUYER of its intention to effect such
            transfer, sale, assignment or pledge. Each such notice shall
            describe the manner and circumstances of the proposed transfer,
            sale, assignment or pledge in sufficient detail, and shall be
            accompanied, at SELLER's expense, by an unqualified written opinion
            of legal counsel who shall, and whose legal opinion shall, be
            reasonably satisfactory to BUYER and addressed to BUYER, to the
            effect that the proposed transfer of the shares may be effected
            without registration under the Act, whereupon the holder of such
            shares shall be entitled to transfer them in accordance with the
            terms of the notice delivered by the holder to BUYER. Each such
            notice


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            shall also be accompanied by a written agreement of the proposed
            transferee to conform to the requirements hereof. Each certificate
            evidencing the securities transferred as above provided shall bear,
            except if such transfer is made pursuant to Rule 144, the
            appropriate restrictive legend set forth above, except that such
            certificate shall not bear such restrictive legend if in the opinion
            of counsel for such holder and BUYER such legend is not required to
            order to establish compliance with any provision of the Act.

            (h) SELLER will execute and deliver to BUYER any document, or do any
            other act or thing, which BUYER many reasonably request in
            connection with any transfer or acquisition of shares under this
            agreement.

            (i) SELLER has not distributed any written materials furnished by
            BUYER to anyone other than SELLER's professional advisors.

            (j) SELLER represents that the statements made and other information
            provided in this Agreement, and all other information with respect
            to the financial position and business experience of SELLER which
            has been previously supplied by SELLER to BUYER are complete and
            accurate as of the date this Agreement is executed by SELLER, and,
            if there should be any material change in such information prior to
            the acceptance or rejection of this Agreement, SELLER will
            immediately provide revised information to BUYER.

            (k) SELLER further represents that SELLER is familiar with the type
            of investment which the shares received in compensation hereunder
            constitute. SELLER believes that any shares received hereunder are
            shares of the kind SELLER wishes to acquire and that the nature of
            the shares received and the amount of the purchase price received in
            shares is consistent with the overall investment program and
            financial position of SELLER. SELLER's overall commitment to
            investments which are not readily marketable is not disproportionate
            to SELLER's net worth; SELLER's investment in BUYER will not cause
            such overall commitment to become excessive; and SELLER can afford
            to bear the loss of SELLER's entire investment in BUYER. SELLER has
            adequate means of providing for SELLER's current needs and personal
            contingencies and has no need for liquidity in its investment in
            BUYER.

            (l) SELLER has such knowledge and experience in financial and
            business matters in general to evaluate the merits and risks of the
            prospective investment and to make an informed investment decision.


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<PAGE>   10


            (m) SELLER understands that no federal or state agency has made any
            finding or determination regarding the fairness of the shares or any
            recommendation or endorsement concerning an investment in BUYER.

            (n) SELLER represents and warrants that there is no finder's fee or
            commission payable SELLER with respect to its receipt of shares
            hereunder.

            (o) SELLER understands that no securities administrator of any
            governmental agency has made any finding or determination relating
            to the fairness of this investment and that no securities
            administrator of any state has recommended or endorsed, or will
            recommend or endorse, the offering of any securities received
            hereunder.


         10. Allocation of Liability and Indemnifications.

            (a) Definitions.

                The term "BUYER's Assumed Liabilities" shall mean and include:

                (i) All costs, expenses, liabilities and obligations or
                otherwise agreed to be paid by BUYER pursuant to the terms of
                this Agreement; and

                (ii) All costs, expenses, liabilities, claims and obligations
                arising out of, in connection with, or resulting directly or
                indirectly from the ownership or operation of the Assets
                (excluding SELLER's Retained Liabilities), insofar as such
                claims relate to periods of time subsequent to the Effective
                Date.

                The term "SELLER's Retained Liabilities" shall mean and include:

                (i) All costs, expenses, liabilities and obligations or
                otherwise agreed to be paid by SELLER pursuant to the terms of
                this Agreement;

                (ii) All costs, expenses, liabilities, claims and obligations
                arising out of, in connection with, or resulting directly or
                indirectly from the ownership or operation of the Assets,
                insofar as such claims relate to periods of time prior to the
                Effective Date, insofar as SELLER knew, or should have known, of
                the cost expense, liability claim and/or obligation; and


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<PAGE>   11


                (iii) All legal fees charged to the joint account and
                attributable to the interests purchased and sold hereunder prior
                to the Effective Date.


            (b) Liabilities. BUYER agrees to assume, pay, perform, fulfill,
            discharge and be liable for all of BUYER's Assumed Liabilities, and
            SELLER agrees to retain, perform, fulfill, discharge and be and
            remain liable for all of SELLER's Retained Liabilities.

            (c) SELLER's Indemnity. SELLER AGREES TO DEFEND, INDEMNIFY AND HOLD
            HARMLESS BUYER, ITS OFFICERS, DIRECTORS, AGENTS AND EMPLOYEES, OR
            ANY OF THEM, FROM AND AGAINST ANY AND ALL LOSSES, CLAIMS, SUITS,
            CONTROVERSIES, LIABILITIES AND EXPENSES (INCLUDING, WITHOUT
            LIMITATION, COURT COSTS, REASONABLE EXPENSES OF LITIGATION AND
            REASONABLE ATTORNEY'S FEES) ARISING DIRECTLY OUT OF SELLERS'
            OWNERSHIP OR USE OF THE INTEREST IN THE ASSETS TO BE PURCHASED
            HEREUNDER; PROVIDED, HOWEVER, THAT THIS INDEMNITY SHALL BE LIMITED
            TO THOSE CLAIMS, RIGHTS, DEMANDS AND CAUSES OF ACTION ARISING FROM
            ACTIVITY OCCURRING PRIOR TO THE EFFECTIVE DATE OF THE SALE.

            (d) BUYER's Indemnity. BUYER AGREES TO DEFEND, INDEMNIFY AND HOLD
            HARMLESS SELLER, SELLER'S HEIRS, PERSONAL REPRESENTATIVES AND
            ASSIGNS, OR ANY OF THEM, FROM AND AGAINST ANY AND ALL LOSSES,
            CLAIMS, SUITS, CONTROVERSIES, LIABILITIES AND EXPENSES (INCLUDING,
            WITHOUT LIMITATION, COURT COSTS, REASONABLE EXPENSES OF LITIGATION
            AND REASONABLE ATTORNEY'S FEES) ARISING DIRECTLY OUT OF BUYER'S
            OWNERSHIP OR USE OF THE INTEREST IN THE ASSETS TO BE PURCHASED
            HEREUNDER; PROVIDED, HOWEVER, THAT THIS INDEMNITY SHALL BE LIMITED
            TO THOSE CLAIMS, RIGHTS, DEMANDS AND CAUSES OF ACTION ARISING FROM
            ACTIVITY OCCURRING AFTER THE EFFECTIVE DATE OF THE SALE.


11. Review and Inspection of the Assets. Prior to the Closing, BUYER shall have
the right to perform due diligence reviews and inspections of the Assets.
Immediately after Closing, SELLER shall transmit to BUYER all paperwork,
information and data relating to the Assets in the possession of SELLER (and to
which SELLER has the right to possession) including, but not limited to, the
following: (a) financial and accounting records; (b) production, engineering,
geological and geophysical data and reports for the


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<PAGE>   12


Leases; (c) copies of engineering, geological and geophysical studies, subject
to any license and non-disclosure requirements; (d) copies of seismic data
across any of the Leases (subject to any license restriction and non-disclosure
requirements); (e) title records, including, but not limited to, copies of the
Leases; (f) correspondence and material and relevant information concerning
pending litigation; (g) regulatory compliance records; (h) contracts between
SELLER and third parties with regard to the Assets; and (i) all correspondence
of any nature relating to the assets, including, without limitation,
correspondence between SELLER and Operator and entities related to Operator,
copies of correspondence between Operator and third-parties and correspondence
of any nature between SELLER and any third party relating to the assets; (j) all
permits and licenses pertaining to the Assets. Nothing contained in this
paragraph shall obligate SELLER to take any action or expend any money to
acquire anything for BUYER which SELLER does not already have in its possession.
SELLER does not warrant the accuracy of any such material.

         12. Waiver. SELLER and BUYER certify that they are not "Consumers"
within the meaning of the Texas Deceptive Trade Practices - Consumer Protection
Act, Subchapter E of the Chapter 17, Sections 17.41 et seq., of the Texas
Business and Commerce Code, as amended (the "DTPA"). The parties covenant, for
themselves and on behalf of any successors and assignees, that if the DTPA is
applicable (a) the parties are "business consumers" thereunder, (b) each party
hereby waives and releases all of its rights and remedies thereunder (other than
Section 17.555, Texas Business and Commerce Code) as applicable to the other
party and its successors, and (c) each party shall defend and indemnify the
other from and against any and all claims, demands, or causes of action of or by
that party or any successor or any of its affiliates based in whole or in part
on the DTPA, arising out of or in connection with the transaction set forth in
this Agreement.


                            WAIVER OF CONSUMER RIGHTS

                  PURCHASER WAIVES ITS RIGHTS UNDER THE DECEPTIVE TRADE
                  PRACTICES - CONSUMER PROTECTION ACT, SECTION 17.41 ET SEQ.,
                  TEXAS BUSINESS & COMMERCE CODE, A LAW THAT GIVES CONSUMERS
                  SPECIAL RIGHTS AND PROTECTIONS. AFTER CONSULTATION WITH AN
                  ATTORNEY OF BUYER'S OWN SELECTION, BUYER VOLUNTARILY CONSENTS
                  TO THIS WAIVER.

         13. Notices. All communications required or permitted under this
Agreement shall be in writing and communications or delivery hereunder shall be
deemed to have been fully made if actually delivered, or if mailed by registered
or certified mail, postage prepaid, return receipt requested, to the address as
set forth below:


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<PAGE>   13


         SELLER:

                           ELISA A. STONER
                           9517 Desert Hills Lane
                           El Paso, Texas
                           79925
                           Telephone:  (915) 598-7834
                           Telecopier:  (915) 772-0907


         BUYER:

                           TIPPERARY CORPORATION
                           633 Seventeenth St., Suite 1550
                           Denver, Colorado  80202
                           Attention: Mr. David L. Bradshaw, President
                           Telephone:  (303) 293-9379
                           Telecopier:  (303) 292-3428

         14. Governing Law. THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF TEXAS, EXCLUDING, HOWEVER, ANY
PROVISION OF THE TEXAS LAW THAT WOULD REQUIRE THE APPLICATION OF THE LAW OF A
DIFFERENT JURISDICTION.

         15. Further Assurances. Incidental and subsequent to Closing, each of
the parties shall execute, acknowledge, and deliver to the other such further
instruments (including any stamp duty or other form necessary for, or incident
to, the notation, sanction, approval, transfer or assignment to BUYER of any
title or interest in either the Assets or the Operating Agreement), and to take
such other actions as may be reasonably necessary to carry out the provisions of
this Agreement.

         16. Government Approvals. SELLER will cooperate with BUYER, in a timely
manner (both before and after closing), in obtaining any necessary or desired
consents or approvals of the Government of Australia or any state thereof,
including, without limitation, the execution of any documents necessary (in the
opinion of BUYER and its counsel) to obtain any consent or approval of interests
arising under the Operating Agreement, or to perfect the title of BUYER or
SELLER in the Assets and/or to obtain any necessary governmental sanction of the
Operating Agreement.

         17. Expenses. Whether or not the transactions contemplated by this
Agreement are consummated, each of the parties hereto shall pay its own fees and
expenses incident to the negotiation, preparation and execution of this
Agreement, including attorney's and accountant's fees.


                                       13
<PAGE>   14


         18. Existing Relationship. SELLER and BUYER are co-signatories to the
Operating Agreement and co-owners in the various rights, interests, contracts
and agreements which, as to SELLER's interests, constitute the Assets. As such,
BUYER AND SELLER have equal rights to information relating to and concerning the
assets and operations. To the extent SELLER may have been provided with
information that has not been provided to BUYER, however, SELLER will provide
such information to BUYER prior to the Closing Date. SELLER acknowledges that
she is experienced and knowledgeable in the oil and gas industry, and has relied
solely on her own legal, tax and other professional counsel concerning this
Agreement.

         19. Exhibits. All exhibits to this Agreement are incorporated herein by
reference.

         20. Successors and Assigns. The terms, covenants and conditions hereof
bind and inure to the benefit of BUYER and SELLER and their respective heirs,
personal representatives, and assigns. This Agreement shall be freely and fully
assignable by BUYER.

         21. Conflicts. In the event of a conflict between this Agreement and
the terms and conditions of the Operating Agreement, the provisions of the
Operating Agreement shall prevail. In all other respects, this Agreement shall
supersede all prior agreements between the parties hereto regarding the subject
matter hereof, whether written or oral.

         22. Survival. The covenants, obligations, indemnities, representations
and warranties included in this Agreement shall survive the Closing and remain
actionable thereafter.

         23. Product of Negotiation. This Agreement is the product of
negotiation between BUYER and SELLER. No fiduciary duty, if any, owed by BUYER
and SELLER in any prior agreement shall apply to the process of negotiation of
this Agreement.

         24. Execution, Counterparts and Exhibits. BUYER and SELLER acknowledge
and agree that this Agreement may be executed in any number of counterparts,
each of which shall be an original, but all of which together shall constitute
one instrument, and that a facsimile copy of this Agreement, and of a signature
to this Agreement, shall be valid and binding as an original. BUYER and SELLER
also acknowledge and agree that they are each in possession of the Exhibits
referred to herein as "A" - "E," and each party shall be responsible for
attaching copies of such exhibits to executed copies of this Agreement. Exhibits
"F" and "G" have been provided to SELLER by BUYER, and shall be attached to this
Agreement by SELLER at the time of execution.


                                       14
<PAGE>   15


         IN WITNESS WHEREOF, this Agreement has been executed by the parties
before the undersigned competent witnesses on the dates indicated below.


SELLER:                                     BUYER:


ELISA A. STONER                             TIPPERARY CORPORATION



By:                                  By:
   ---------------------------------    ----------------------------------------
   Elisa A. Stoner                      David L. Bradshaw
                                        President and Chairman of the Board



ATTEST:                              ATTEST:



By:                                  By:
   ---------------------------------    ----------------------------------------


STATE OF TEXAS      )
                    )
COUNTY OF EL PASO   )


         The foregoing instrument was acknowledged before me on this the _______
day _____________, ____by Elisa A. Stoner, as Seller.

Witness my hand and official seal.



                                       ----------------------------------------
                                       Notary Public
                                       THE STATE OF TEXAS

My Commission Expires:

--------------------


                                       15
<PAGE>   16


STATE OF COLORADO   )
                    )
COUNTY OF DENVER    )


         The foregoing instrument was acknowledged before me on this the _______
day of _______________, 2000 by David L. Bradshaw, President of Tipperary
Corporation, on behalf of said corporation, as Buyer.




Witness my hand and official seal.



                                        ----------------------------------------
                                        Notary Public
                                        THE STATE OF COLORADO

My Commission Expires:

--------------------


                                       16