Document:

OIL AND GAS LEASE PURCHASE CONTRACT

THIS OIL AND GAS LEASE PURCHASE CONTRACT (this "Contract") is made and entered
into as of the Effective Date (hereinafter defined), by and between SCOPE
OPERATING COMPANY, a Texas Corporation, ("Seller') and KEYSTONE SILVER MINES,
INC., an Idaho corporation, ("Purchaser"), for and in consideration of the
mutual terms, provisions and covenants contained herein, and other good and
valuable consideration the receipt and sufficiency of which is hereby
acknowledged and confessed, and in respect thereof the parties hereto agree as
follows:

1.   CONTRACT TO ASSIGN. Seller agrees to grant, sell, transfer, assign and
     convey to Purchaser, A 25% WORKING INTEREST (18.75% NET REVENUE INTEREST),
     in and to that certain Oil and Gas Lease(s) (the "Lease(s)"), together with
     the same interest in all personal property and equipment located on and
     associated with the Lease(s) and the other property to be delivered to
     Purchaser hereunder (such property and equipment, the Lease(s), and all
     property rights connected with the Lease(s) shall be referred to herein
     collectively as the "Lease Property")

                                    LEASE(S)
Lease:              Felts
County:             Montgomery
State:              Kansas
Acres:              90
W.I.                25%
N.R.I.:             18.75%

(More particularly described in Exhibit A, attached to and made a part of this
contract by reference.)

2.   PURCHASE PRICE.

     The purchase price for the lease property shall be $62,500, and shall be
     paid by Purchaser to Seller, subject to the other terms and conditions
     provided herein, on or before the effective date. The balance due, $62,500,
     can be paid in cash or company stock at the discretion of the purchaser. If
     paid in company stock, the number of shares issued to Seller shall be
     625,000 ($0.10 per share).

                 THE REST OF THIS PAGE INTENTIONALLY LEFT BLANK

<PAGE>

3.   LEASE PROPERTY INFORMATION. On or before the Effective Date, Seller shall
     furnish to Purchaser, at Seller's expense, legible copies of any and all
     documents, materials or information in Seller's possession related to the
     Lease(s) and the Lease Property, including but not limited to, the
     following:

(i)  All agreements and contracts relation to ownership and operation of the
     Lease Property, including all Operating Agreements (herein so called)
     regarding oil and gas operations, water injection and pipeline
     transportation;

(ii) All delay rental receipts and other documents and information sufficient to
     show proof of how the Lease(s) have been kept effective since execution;

(iii)All division orders, division order title opinions, pipeline title opinions
     and all other title opinions regarding the Lease(s);

(iv) All drilling and production information in possession of Seller regarding
     the Lease(s), including mud logs and electric logs;

(v)  copies of all documents and information regarding utility expenses, and
     repair and maintenance costs, incurred in the operation of the Lease
     Property;

(vi) copies of all governmental licenses, permits and other documents, including
     federal and state oil and gas regulatory reports and filling, regarding the
     Lease(s) and the Lease Property;

(vii) All insurance policies covering the Lease Property;

(viii) A complete, itemized and detailed inventory of the Lease Property; and

(ix) All maps, plans, surveys and geologic information, and any and all other
     information in Seller's possession, related to the Lease(s) and the Lease
     Property.

4.   CLOSING. The sale and purchase of the Lease Property, shall be consummated
     at a closing (the "Closing") to be held at Seller's or such other site as
     may be mutually acceptable to the parties hereto, on or before the
     Effective Date (such date being the "Closing Date").

5.   DELIVERIES AT CLOSING. At Closing, Seller shall (i) deliver an Assignment
     (herein so called) of the Lease Property in recordable form, which
     Assignment shall include warranties that Seller possesses good and
     marketable title to the Lease(s) and the Lease Property, that the Lease(s)
     and the Lease Property are free and clear of any liens and encumbrances,
     and that the Lease(s) is in full force and effect, (ii) execute and deliver
     to Purchaser notices to all production purchasers from the Lease(s) of its
     assignment to Purchaser, and transfer orders directing purchasers of
     production from the Lease(s) to make payment to Purchaser, (iii) execute
     and deliver to purchaser all regulatory forms and documents necessary or
     appropriate to transfer title, operations, production and all other matters
     regarding the Lease Property to Purchaser, (iv) deliver to Purchaser all
     original files, documents and records pertaining to the Lease(s) and the
     Lease Property, (v) obtain the written consent of the Lease(s) lessors to
     the assignment contemplated herein, and (vi) furnish and/or execute all
     other documents reasonably required to close the purchase and sale of the
     Lease Property (including a bill of sale for the items of personal property
     constituting the Lease Property). In case of dispute as to the form of the
     Assignment, the appropriate form promulgated by the American Association of
     Professional Landmen (A.A.P.L.) shall be used. Possession of the Lease
     Property shall be delivered to the Purchaser at closing. Both prior and
     subsequent to Closing, Seller and Purchaser shall cooperate with and assist
     each other in the transfer and assignment of the Lease(s) and the Lease
     Property to Purchaser by taking all reasonable and appropriate actions
     requested by the other party, including the execution by Seller of release
     documents, such as a release of interest in and to any division orders
     affecting the Lease(s).

6.   PRORATIONS. All production revenue from the Lease(s), and all taxes
     attributable to ownership to the Lease Property (including, all severance
     taxes, all ad valorem taxes assessed by any city, county, district, school
     or city or county education district, and all personal taxes), shall be
     prorated between Purchaser and Seller through the Closing Date for the
     month and year in which the Closing is held, based on the tax and other
     statements for such month or year; provided, however, that if such tax or
     other statements for the subject time period are not available on the
     Closing Date, proration of taxes shall be made on the basis of taxes
     assessed in the previous applicable time period. Payment for a party's
     portion of production from the Lease(s) shall be remitted promptly upon
     receipt of payment from the production purchaser, such payment to reflect
     the amount Seller would have received if production had been sold to the
     production purchaser by Seller directly.

<PAGE>

7.   SELLER'S COVENANTS. Seller hereby covenants to and agrees with Purchaser as
     follows:

(i)  Seller shall keep and perform all of the obligations to be performed by the
     lessee under the Lease(s);

(ii) Seller shall obtain all such written consents and approvals as may be
     required in order to permit Seller to perform its obligations under this
     Contract, specifically including the written consent of the Lease(s)
     lessors and required under the Lease(s);

(iii)Seller shall conduct all operations on the Lease Property in accordance
     with prudent oil and gas standards and all applicable laws, after execution
     of this Contract, Purchaser shall have the right to approve all new
     contracts or other agreements entered into, and all amendments,
     modifications or terminations of such contracts or agreements, respecting
     the Lease(s) and all Lease Property; and

(iv) Seller shall cause all trade accounts and costs and expenses of operation
     and maintenance of the Lease Property to be promptly paid when due.

8.   SELLER REPRESENTATIONS. In addition to the representations and warranties
     contained in other paragraphs of this Contract, Seller hereby represents
     and warrants to Purchaser, which representations and warranties shall be
     true and correct as of, and shall survive the termination or expiration of
     this Contract, and the truth of which shall be a condition precedent to
     Purchaser's obligations hereunder, that:

(i)  All Lease Property is in compliance with all laws, rules and regulations,
     of all federal, state, municipal and other oil and gas regulatory
     departments, commissions, boards, bureaus, agencies and instrumentalities,
     having jurisdiction over the Lease Property, and Seller has obtained and
     possess all permits and approvals from such regulators as are necessary to
     operate the Lease(s) in its current condition;

(ii) There are not actions, suits, proceedings, investigations or set of facts,
     which are existing, pending or, to the best knowledge and belief of Seller,
     threatened or asserted against Seller or any portion of item of the Lease
     Property, whether at law or in equity or before or by any federal, state,
     municipal or other governmental department, commission, board, bureau,
     agency or instrumentality, domestic or foreign, or otherwise existing, and
     Seller has not received any notices of any condemnation actions, special
     assessments or increase to the asserted valuation of taxes or other
     impositions of any nature which are pending or being contemplated with
     respect to the Lease Property or any portion thereof.

(iii)There are no liens (recorded or unrecorded), assessments, or security
     interests against the Lease(s) or against any portion of the Lease
     Property, nor are there any actions pending which would result in the
     creation of any lien or claim against the Lease(s) or Lease Property, and
     Seller shall not create or voluntarily permit to be created any liens,
     easements or other conditions affecting any portion of the Lease(s) or the
     Lease Property without the prior written consent of Purchaser. At the
     conclusion of all Program activities, there will be no unpaid bills or
     claims in connection with any construction, repair, maintenance, drilling,
     development or other work performed or material purchased in connection
     with the Lease(s) or the Lease Property, and no part of the Lease Property
     has been destroyed or damaged by fire or other casualty;

(iv) Seller has all requisite power and authority to own its property, operate
     its business where now conducted, enter into this Contract and consummate
     the transactions herein contemplated, and if other than an individual is
     duly authorized to do business and validity existing under the laws of the
     state of its formation, and by proper action has duly authorized the
     execution and delivery of this contract and the consummation of the
     transaction herein contemplated, and no permission, approval or consent by
     third parties or governmental authorities is required in order for Seller
     to consummate this Contract, and the party signing this Contract on behalf
     of Seller has the power and authority to sign this Contract on behalf of
     Seller, and the other parties having ownership interests in the Lease(s)
     and Lease Property;

(v)  This Contract is a valid obligation of Seller and is binding upon Seller in
     accordance with its terms:

(vi) Seller is the owner of good and marketable title to the Lease(s) and all
     Lease Property, free and clear of any liens, deeds of trust, pledges,
     security interests, leases, charges, encumbrances or restrictions of any
     kind;

<PAGE>

(vii)Seller is not a party to or bound under any indenture, mortgage, deed of
     trust or loan agreement or any other agreements which in any way affects
     the Lease(s) or the Lease Property, and to the best of its knowledge,
     Seller is not a party to, nor bound by, any agreement or any order or
     decree of any court or governmental agency which might to a material degree
     adversely affect any portion of the Lease(s) of the Lease Property;

(viii) The executed copy of the Lease(s) which has been or will be delivered to
     Purchaser in accordance with the terms of this Contract (and to be assigned
     at closing) are and shall be true and correct; the Lease(s) is in full
     force and effect, and is being held by production, or if not being held by
     production, the Lease(s) is otherwise being validly held by some other
     appropriate action (e.g., commencement of drilling operations, or payment
     of rentals or shut-in royalties to all necessary lessors); the Lease(s)
     shall not be further modified or amended without the prior written consent
     of Purchaser, no other party has any purchase option, right of first
     refusal, or other interest in the Lease(s); no lessor has given Seller
     notice of its intention to terminate the Lease(s); and there are no pending
     claims (whether monetary or otherwise) made against Seller as lessee under
     the Lease(s); and

(ix) All permits, licenses and certificates which have been obtained by Seller
     with respect to the Lease(s) shall be maintained through closing and Seller
     knows of no reason why same will not continue unimpaired after the
     assignment of the Lease(s) to Purchaser.

9.   PURCHASER REPRESENTATIONS. Purchaser hereby represents and warrants to
     Seller as follows:

(i)  Purchaser has all requisite power and authority to own its property,
     operate its business where now conducted, enter into this contract and
     consummate the transactions herein contemplated, and if other than an
     individual is duly authorized to do business and validly existing under the
     laws of the state of its formation, and by proper action has duly
     authorized the execution and delivery of this Contract and the consummation
     of the transaction herein contemplated, and no permission, approval or
     consent by third parties or governmental authorities is required in order
     for Purchaser to consummate this Contract, and the party signing this
     Contract on behalf of Purchaser has the power and authority to sign this
     Contract on behalf of Purchaser; and

(ii) Neither the execution nor delivery of this Contract by Purchaser will
     result in a violation or breach of any term or provision or constitute a
     default under any agreement to which Purchaser is a party.

10.  SUBSEQUENT DISCLOSURES; RELIANCE. In the event that either party hereto
     should discover that any representation or warranty made by it is untrue or
     inaccurate, it shall promptly inform the other party in writing of its
     discovery. Each party's obligations hereunder are expressly conditioned
     (which condition may be waived by the party to whose benefit the
     representation or warranty is made) upon the lack of any material variance
     with respect to the truth and accuracy of all warranties and
     representations which are made by the other party. All warranties and
     representations contained herein shall survive the Closing. Seller
     acknowledges and agrees that Purchaser has and will rely upon the
     covenants, agreements, representations, and warranties set forth in this
     Contract in purchasing the Lease Property and that said covenants,
     agreements, representations, and warranties are essential conditions but
     for which Purchaser would not acquire the Lease Property. The covenants,
     agreements, representations, and warranties herein contained shall be
     binding upon Seller, its successors, assigns, and legal representatives,
     shall inure to the benefit of Purchaser, its successors, assigns and legal
     representatives, and shall survive the Closing of the sale and purchase of
     the Lease Property. If any representation of Seller contained herein is
     untrue as of the Closing, this Contract may be terminated by Purchaser.

11.  BROKERS. Purchaser and Seller hereby represent and warrant that they have
     not incurred any liability or obligation for any broker's or finder's fees,
     commissions or similar costs or expenses in connection with the sale of the
     Lease Property, and each agrees to indemnify, defend and hold the other
     harmless from and against any such liability or obligation which may be
     asserted against the other party by through or under it.

12.  MISCELLANEOUS PROVISIONS. Purchaser and Seller hereby agree to be bound by
     the following terms and provisions:

<PAGE>

A.   NOTICES. Unless otherwise provided, all notices and other communications
     required or permitted hereunder shall be in writing and shall be deemed
     delivered for all purposes, (I) on the date of actual receipt if delivered
     in person, (ii) on the date of actual receipt if sent via facsimile and a
     confirmation copy is sent via commercial delivery or parcel service, (iii)
     whether received or not, on the date deposited with a commercial delivery
     or parcel service if delivery is documented by such service, and (iv)
     whether received or not, on the date deposited with the United States
     Postal Service, if sent via registered or certified mail, postage prepaid,
     return receipt requested; and, in the case of (iii) and (iv) above, when
     addressed to the intended recipient at the address set forth on the
     signature page of this Contract or at such other address as a party hereto
     may specify by notice in compliance with the requirements of this
     Paragraph.

B.   ENTIRE AGREEMENT. This contract contains the complete and entire agreement
     between the parties hereto with respect to the matter contained herein and
     cannot be varied except by written agreement. The parties hereto agree that
     there are no other agreements, understanding, representations or warranties
     between the parties hereto which are not expressly set forth herein, and
     that the terms and provisions of this Contract supersede all other
     agreements, understanding, representations or warranties between the
     parties hereto which may have arisen heretofore or contemporaneously
     herewith.

C.   EFFECTIVE DATE. The term "Effective Date", as used herein, shall mean the
     latter of the two dates on which this Contract is signed by Seller and
     Purchaser, as indicated under their signatures below, which latter date
     shall be the date of final execution and agreement by the parties hereto;
     provided, however, if the last party to execute this Contract fails to
     complete the date of execution below the party's signature, the Effective
     Date shall mean that date shown below the first party to sign and date this
     Contract.

D.   BUSINESS DAY. If any date of performance hereunder falls on a Saturday,
     Sunday or legal holiday, such date of performance shall be deferred to the
     next day which is not a Saturday, Sunday or legal holiday.

E.   SEVERABILITY. In case any one or more of the provisions contained in this
     Contract shall for any reason be held to be invalid, illegal, or
     unenforceable in any respect by a court of competent jurisdiction, such
     invalidity, illegality, or unenforceability shall not affect any other
     provisions hereof, and this Contract shall be construed as if such invalid,
     illegal, or unenforceable provision is severed and deleted from this
     Contract.

F.   COUNTERPARTS; FACSIMILE EXECUTION. This contract may be executed in a
     number of identical counterparts, and for convenience may be executed via
     facsimile. Each such counterpart shall be deemed an original for all
     purposes and all such counterparts shall collectively, constitute one
     agreement, but, in making proof of this contract, it shall be necessary to
     produce or account for more that one counterpart. Each party shall be
     entitled to rely upon the other's execution and delivery of this Contract
     via facsimile for all purposes and in making proof of this Contract.

G.   HEADINGS. The headings on the Paragraphs and Sub-paragraphs of this
     Contract are for convenience only and shall in no way enlarge, limit or in
     any way effect the scope or meaning of the terms and provisions of this
     Contract.

IN WITNESS WHEREOF, Purchaser and Seller have executed this Contract to be
effective as of the Effective Date as evidenced by their respective signatures
below.

PURCHASER:                                       SELLER:
----------                                       -------
KEYS STONE SILVER MINES, INC                     SCOPE OPERATING COMPANY

By: \s\ S. Jeff Johnson                          BY: \s\ S. Jeff Johnson
   -----------------------                          -------------------------
Name:   S. Jeff Johnson                          Name:   S. Jeff Johnson
Title:  President                                Title:  President
Date:   April 11, 2000                           Date:   April 11, 2000

(The remainder of this page is left blank intentionally.)

<PAGE>

                                    EXHIBIT A
LEASE:                     Felts
INTERESTS:                 25% W.I., 18.75% N.R.I.
PRICE:                     $62,500
DESCRIPTION:               The Felts is composed of the following:

That certain Oil, Gas and Mineral Lease dated December 15, 1997, executed by
Richard W. Felts and Shirley M. Felts, Husband and Wife; Larry D. Felts and Ruth
A. Felts, Husband and Wife, as Lessor to Potato Creek L.L.C., as Lessee, said
lease being recorded in Book 465, Page 413 in so far as said Lease covers the
following described land in Montgomery County, State of Kansas:

Lot 6: and the North three-fourths (3/4) of Lot 7 lying East of the river, less
railroad right of way; the North three-fourths (3/4) of the NW/4 of the SE/4
lying west of Highway 169, except railroad right of way; all in Section 30,
T345, R17E, Montgomery County, Kansas, containing 90 acres more or less.PETROLEUM CONSULTANTS, INC.
        7830 State Line Road o Suite 100 o Prairie Village, Kansas 66208
--------------------------------------------------------------------------------
                         Telephone: (913) 341-1465
                               Fax: (913) 341-1325

Reservoir Engineering                                              Gas Contracts
Property Evaluation                                                Gas Marketing
Regulatory Affairs                                                Expert Witness

                                  May 25, 2000

Mr. Dwight Brehm
Vice-President
Scope Operating Company
808 S. College, Ste. 300
McKinney, Texas 75069

Dear Mr. Brehm:

         Attached is an updated evaluation on the Felts oil lease located in
Section 30-T34S-R17E, Montgomery County, Kansas. The appraised value is
estimated at $447,144.00. The effective date of this appraisal is April 11,
2000.

         This appraisal is based on a working interest of 25% and a net revenue
of 18.75%, which is owned by Keystone Silver Mines, Inc. An oil price of $25.00
per barrel was used and the appraisal is on a non-escalated basis, where price
and the expenses were kept constant throughout the life of the property. The
economic life of the property is estimated to be 11 years.

         The producing formation is the Red Fork Sandstone. This lease has
produced 20,000 barrels of oil. Combined primary and secondary operations should
recover an estimated 191,000 barrels of oil. Reservoir characteristics, such as
porosity and permeability, indicate that the formation will flood successfully.
The initial phase of secondary recovery would be a waterflood, followed by a
polymer augmented flood. It is anticipated that the polymer flood would plug the
thief zones and improve the areal and vertical sweep efficiency of the
reservoir. This would result in increased oil recovery that otherwise would not
be recovered.

         If you have any questions please let me know.

                                                  Sincerely,

                                                  /s/ Ronald L. Cook

                                                  Ronald L. Cook, P.E.

[seal of Ronald L. Cook here]

<PAGE>
<TABLE>

PRODUCTION RATE FORECAST AND EVALUATION
Before Federal Income Tax                         Well Name: Felts
                                                  Operator: Keystone Silver Mines, Inc.
Project Name: Felts                               Field:
AS OF: April 11, 2000                             Reservoir: Red Fork
Prepared By: Ron Cook                             Location: Section 30-T34S-R17E
                                                  County, State: Montgomery, Kansas

Comments: Proved Developed - Escalated case
<CAPTION>

          Gross Production     Net Production     Price   Price    Gas Net     Oil Net  Net Oper   Wpt Tax   Net Oper    Total
 Year       Gas       Oil      Gas       Oil       Gas     Oil     Revenue     Revenue   Revenue   +Adv+Sev  Expense    Invest
Ending    (Mmcf)    (Mbbl)    (Mmcf)    (Mbbl)    ($/M)   ($/B)      (M$)       (M$)       (M$)      (M$)      (M$)      (M$)
------    ------    ------    ------    ------    ------  ------   ---------  ---------  --------  --------  --------  --------
<S>       <C>       <C>       <C>       <C>       <C>     <C>      <C>        <C>        <C>       <C>       <C>       <C>
                                                                                            Initial Investment         0.000
 12  0    0.00    30.000      0.00      5.625     0.000   25.00    0.00       140.63     140.63     12.656    9.750    0.000
 12  1    0.00    36.000      0.00      6.750     0.000   25.00    0.00       168.75     168.75     15.187   12.000    0.000
 12  2    0.00    36.000      0.00      6.750     0.000   25.00    0.00       168.75     168.75     15.187   12.000    0.000
 12  3    0.00    30.000      0.00      5.625     0.000   25.00    0.00       140.63     140.63     12.656   11.000    0.000
 12  4    0.00    15.000      0.00      2.813     0.000   25.00    0.00        70.31      70.31      6.328    9.000    0.000

 12  5    0.00    12.000      0.00      2.250     0.000   25.00    0.00        56.25      56.25      5.063    9.000    0.000
 12  6    0.00     9.600      0.00      1.800     0.000   25.00    0.00        45.00      45.00      4.050    9.000    0.000
 12  7    0.00     7.700      0.00      1.444     0.000   25.00    0.00        36.09      36.09      3.248    9.000    0.000
 12  8    0.00     6.100      0.00      1.144     0.000   25.00    0.00        28.59      28.59      2.573    9.000    0.000
 12  9    0.00     5.000      0.00      0.938     0.000   25.00    0.00        23.44      23.44      2.109    9.000    0.000

 12 10    0.00     4.000      0.00      0.750     0.000   25.00    0.00        18.75      18.75      1.687    9.000    0.000
        ------   -------    ------     ------    ------  ------   ---------  ---------  --------  --------  --------  --------
Total     0.00   191.400      0.00     35.887             25.00    0.00       897.19     897.19     80.747  107.750    0.000
Years:  11.
</TABLE>
<TABLE>
<CAPTION>
<S>                 <C>            <C>                           <C>       <C>        <C>         <C>

                      Initial        Final                                   Cash      Cum Cash  Disc Cash
                      -------        -----                         Year      Flow        Flow    Flow@ 20%
Working Interest     25.00000 %     25.00000 %                   Ending      (M$)        (M$)       (M$)
Gas Net Interest      0.00000 %      0.00000 %                   ------    --------    -------    -------
Oil Net Interest     18.75000 %     18.15000 %                   Init Inv    0.000
                                                                 12  0     118.219     118.219    110.406
Discount Rate       Net Present Value                            12  1     141.563     259.781    112.712
-------------       -----------------                            12  2     141.563     401.344     93.927
       5 %           617.680 M$                                  12  3     116.969     518.313     64.674
      10 %           547.483 M$                                  12  4      54.984     573.297     25.335
      15 %           491.977 M$
      25 %           410.265 M$                                  12  5      42.188     615.484     16.199
                                                                 12  6      31.950     647.434     10.223
Results Saved in File: Macintosh HD:Econ prog:Felts RES          12  7      23.845     671.280      6.358
                                                                 12  8      17.020     688.300      3.782
                                                                 12  9      12.328     700.628      2.283

                                                                 12 10       8.063     708.691      1.244
                                                                           -------    --------    -------
                                                                 Total     708.691     708.691    447.144

</TABLE>

                                                     Petroleum Consultants, Inc.

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