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                                                                    EXHIBIT 10.6

                      ASSIGNMENT AND ASSUMPTION AGREEMENT

     This Assignment and Assumption Agreement (this "Agreement") is made
effective as of 7:00 a.m., June 1, 2000, by and among Crosby Capital LLC, a
Texas limited liability company ("Lender"), and Garnet Resources Corp., a
Delaware corporation ("Garnet").

                                 R E C I T A L

     WHEREAS, pursuant to that certain Loan, Settlement and Acquisition
Agreement dated as of May 31, 2000 (the "Purchase Agreement"), by and among
Lender, and Aviva Petroleum, Inc., a Texas corporation ("Parent"), Aviva
America, Inc., a Delaware corporation ("Aviva America"), Aviva Operating, Inc.,
a Delaware corporation ("Aviva Operating"), Aviva Overseas, Inc., a Delaware
corporation ("Aviva Overseas"), Neo Energy, Inc., a Texas corporation ("Neo"),
Garnet, Argosy Energy, Inc. a Delaware corporation ("Argosy Energy"), and Argosy
Energy International, a Utah limited partnership ("Argosy International")
(Parent, Aviva America, Aviva Operating, Aviva Overseas, Neo, Garnet, Argosy
Energy and Argosy International are referred to collectively herein as the
"Aviva Parties"), Garnet has agreed to sell, grant, convey, transfer, assign and
deliver to Lender all its right, title and interest in the Partnership Interests
in Argosy International.

                               A G R E E M E N T

     NOW, THEREFORE, in consideration of the promises herein and in the Purchase
Agreement, and other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, Garnet and Lender hereby agree as
follows:

     1.   Transfer of Partnership Interest. Garnet hereby conveys, transfers,
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assigns, grants, sells and delivers, to Lender, and Lender acquires, accepts and
purchases, all of Garnet's right, title and interest in the Partnership
Interests, which the parties acknowledge is a 5.0738% limited partnership
interest (the "Garnet Partnership Interest").

     2.   Assumption. Lender hereby assumes and accepts the Garnet Partnership
          ----------
Interest.

     3.   Further Assurances. Garnet shall execute and deliver to Lender such
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further documents and instruments, and take such other action, that may be
reasonably requested by Lender to evidence this conveyance, transfer and
assignment of the Garnet Partnership Interest.

     4.   Definitions. All capitalized terms not otherwise defined herein shall
          -----------
have the meaning ascribed to them in the Purchase Agreement.

     5.   Inurement. The conveyance, assignment and transfer herein shall be
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effective as of the date hereof, and shall inure to the benefit of and be
binding upon the parties hereto and their successors or permitted assigns.
However, nothing in this Agreement, express or implied, shall give any other
person any benefit or any legal or equitable right or remedy with respect
hereto.
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     6.   Conveyance Subject to the Purchase Agreement. This conveyance is made
          --------------------------------------------
pursuant to the Purchase Agreement and is subject to the terms thereof.

     7.   Counterparts. This Agreement may be separately executed in
          ------------
counterparts, each of which when so executed shall be deemed to constitute one
and the same Agreement. Such execution and delivery may be accomplished by
facsimile transmission.

     8.   Governing Law. This Agreement shall be governed by and construed in
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accordance with the laws of the State of Texas, without regard to principles of
conflicts of law thereof.







                           [SIGNATURES ON NEXT PAGE]

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     IN WITNESS WHEREOF, each of the undersigned has caused this Agreement to be
executed as of the day and year first written above.

                                    GARNET RESOURCES CORP.



                                    By: /s/ R. Suttill
                                        --------------
                                        President

                                    CROSBY ACQUISITION, LLC

                                    By:  CROSBY CAPITAL, LLC, as sole member

                                             By: /s/ Jay A. Chaffee
                                                -------------------
                                             Jay A. Chaffee
                                             President

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