<PAGE>
                                   EXHIBIT 10.18

                              STOCK OPTION AGREEMENT
                                     (INSIDER)

MEMORANDUM OF AGREEMENT made as of the 24th day of April, 1995

BETWEEN:

        SUMMO MINERALS CORPORATION, a body corporate, duly
        incorporated under the laws of British Columbia,
        and having its head office at 860 - 625 Howe
        Street, Vancouver, British Columbia, V6C 2T6
        
        (hereinafter called the "Company")
        
                                                             OF THE FIRST PART

AND:

        J. DOUGLAS LITTLE, of 4810 Puget Dr.
        Vancouver, B.C. V6L 2W3

        (hereinafter called the "Optionee")

                                                             OF THE SECOND PART



    WHEREAS the Optionee is an Insider of the Company.



    AND WHEREAS the Company wishes to maintain the continued services of and 
to provide incentive to the Optionee and to this end is desirous of granting to 
the Optionee an option to purchase shares in the capital of the Company 
subject to the terms and conditions hereinafter contained.

NOW THEREFORE THIS AGREEMENT WITNESSETH:

DEFINITION

1.  In this Agreement the term "share" or "shares" means, as the case may be,
    one or more common shares without par value in the capital stock of the 
    Company as constituted at the date of this Agreement.

GRANTING OF OPTION

2.  The Company hereby irrevocably grants to the Optionee, being an Insider of
    the Company, a non-assignable, non-transferable option to purchase 40,000 
    shares in the 

<PAGE>

    capital stock of the Company (hereinafter called the "Option") at $1.20 
    per share (the "Option Price") on the terms and conditions hereinafter set 
    forth.

EXERCISE OF OPTION

3.  The Option, may be exercised by the Optionee over a period of five (5) years
    until April 24, 2000, by notice in writing to the Company to that effect. 
    Any such notice given to the Company (an "Exercise Notice") shall specify 
    the number of shares with respect to which the Option is being exercised 
    and shall be accompanied by a cheque drawn on a Canadian chartered bank in 
    favour of the Company in full payment of the Option Price for the number of 
    shares then being purchased.

DELIVER OF SHARE CERTIFICATE

4.  The Company shall, within five business days after receipt of the         
    Exercise Notice deliver to the Optionee a share certificate representing  
    the number of shares with respect to which the Option is exercised and    
    issued as of the date of the Exercise Notice.

5.  An Exercise Notice shall be deemed to have been given, if delivered, on   
    the date of delivery or if mailed, on the date of mailing. A mailed       
    Exercise Notice shall be sent by prepaid registered mail addressed to the 
    Company at its Vancouver address.

OPTION ONLY

6.  Nothing herein contained or done pursuant hereto shall obligate the       
    Optionee to purchase and/or pay for any shares of the Company, except     
    those shares in respect of which the Optionee shall have exercised all or 
    any part of the Option granted hereunder.

7.  The Optionee shall have no rights whatsoever as a shareholder in respect to 
    any of the shares optioned hereunder other than in respect of optioned 
    shares upon which the Optionee shall have exercised all or any part of the 
    Option granted hereunder and which shall have been taken up and paid for 
    in full.

APPROVAL

8.  The Option granted hereunder is subject to approval by ordinary resolution
    of the members of the Company entitled to vote at a general meeting of 
    the Company, passed prior to the exercise of the Option or any part thereof.

FILING WITH REGULATORY AUTHORITIES

9.  This Agreement may be required to be filed with some or all of the
    Superintendent of Brokers for the Province of British Columbia and the 
    Vancouver Stock Exchange ("VSE") (collectively the "Regulatory 
    Authorities") and the Optionee hereby agrees to

<PAGE>
    
    be bound by any modification of the terms and conditions of the Option as 
    may be required by the said Regulatory Authorities.

10. A Declaration of Stock Option Position as attached hereto as "Schedule A"
    to this Agreement, is required by the VSE and the Option hereby agrees to 
    be bound by any modification of the terms and conditions of the Option as 
    may be required by the said Regulatory Authorities.
    
CAPITAL REORGANIZATION

11. In the event the authorized capital of the Company as presently constituted
    is consolidated into a lessor number of shares or subdivided into a 
    greater number of shares, the number of shares in respect of which the 
    Option remains unexercised shall be decreased or increased 
    proportionately as the case may be, and the then prevailing purchase 
    price to be paid by the Optionee for each such share shall be 
    correspondingly decreased or increased as applicable. In the event the 
    Company shall determine to amalgamate or merge with any other company or 
    companies (and the right to do so is hereby expressly reserved) whether 
    by way of statutory amalgamation, sale of its assets and undertaking, or 
    otherwise howsoever, then and in each such event the number of shares in 
    the corporation resulting from such amalgamation or merger in respect of 
    which the Option remains unexercised shall be such number of shares in 
    that corporation as would have been acquired by the Optionee pursuant to 
    the amalgamation or merger had the Option been fully exercised immediately
    prior to the date of such amalgamation or merger and the then prevailing
    purchase price of the shares to be paid by the Optionee shall be 
    correspondingly decreased or increased as applicable.
    
TERMINATION OF OPTION

12. The Option is not assignable or transferable and shall terminate on the   
    30th day following the date upon which the Optionee ceases to be an       
    Insider of the Company; provided, however, that if such cessation is due  
    to the death of the Optionee, the personal representative of the Optionee 
    shall have the right to exercise any unexercised part of the Option for a 
    period of one year following the date of death of the Optionee.
    
AMENDMENT OF MATERIAL TERMS

13. Any amendment to the Option is subject to approval by ordinary resolution
    of the members of the Company entitled to vote at a general meeting of 
    the Company.

TIME OF THE ESSENCE

14. Time shall be of the essence of this Agreement.

<PAGE>

SUCCESSORS

15. This Agreement shall enure to the benefit of and be binding upon the 
    heirs, executors and administrators of the Optionee and the successors of 
    the Company.

IN WITNESS WHEREOF the parties hereto have caused these presents to be
executed as at the day and year first above written.

The Corporate Seal of SUMMO           )
MINERALS CORPORATION was              )
hereunto affixed in the               )
presence of:                          )
                                      )
                                      )              C/S
/s/ [Illegible]                       )
----------------------------          )
Authorized Signatory                  )
                                      )
                                      )
/s/ [Illegible]                       )
----------------------------          )
Authorized Signatory                  )



SIGNED, SEALED AND DELIVERED          )
by the Optionee in the presence of:   )
                                      )
Name: /s/ Gail Sharp                  )      /s/ J. Douglas Little
      -----------------------------   )      ----------------------------
                                      )      J. DOUGLAS LITTLE
Address: 1002-1460 Barclay            )
         --------------------------   )
         Vancouver B.C.               )
         --------------------------   )
                                      )
Occupation: Secretary                 )
            -----------------------   )


<PAGE>

                                  SCHEDULE "A"

                   DECLARATION OF STOCK OPTION POSITION
                   THIS FORM FOR COMPLETION BY OPTIONEE

RE: 
    --------------------------------------------------
               (Name of Company)

RE:                     incentive stock options in
    -------------------                            ----------------------
      (No. of options)                                    (Company)

I, _____________________, HEREBY CERTIFY that the aforesaid non-transferable 
options have been granted to me in compliance with the requirements of the 
V.S.E. Policy 23: and more particularly that at the time of grant, I was not 
aware of any change in the affairs of the Company which might have affected 
the trading price and had not been disclosed to the public. If the company is 
classified as a Venture Company as of the date of this declaration, I confirm 
that I have not been granted a stock option in the said Company within 2 
years of the date of grant of the above-stated options.

I HEREBY FURTHER CERTIFY (complete either Part I or Part II as applicable):

                                     PART I
THAT I have not be granted any director or employee incentive share options 
by any other listed companies.

DATED the       day of                , 19  . SIGNATURE: 
          -----        --------------     --             -------------------

                                     PART II

THAT I hold as of the date of this Declaration existing incentive share 
options which have been granted to me by the above named company or other 
listed companies as follows:

                                                                  Outstanding
Name of                 No. of                Date of             Balance as
Listed                  Shares                Exercise            at Date of
Co.                     Optioned              Grant               Certificate


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

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

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

(Complete on separate sheet if insufficient space)

DATED the       day of                , 19  . SIGNATURE: 
          -----        --------------     --             -------------------


<PAGE>




                           STOCK OPTION AGREEMENT
                                 (INSIDER)


MEMORANDUM OF AGREEMENT made as of the 24th day of April, 1995


BETWEEN:

    SUMMO MINERALS CORPORATION, a body corporate, duly
    incorporated under the laws of British Columbia,
    and having its head office at 860 - 625 Howe
    Street, Vancouver, British Columbia, V6C 2T6
    
    (hereinafter called the "Company")
    
                                                            OF THE FIRST PART

AND:

    ROBERT A. PRESCOTT, of 1100 - 1776 Lincoln St.
    Denver, Colorado, 80203, USA

    (hereinafter called the "Optionee")

                                                            OF THE SECOND PART

    WHEREAS the Option is an Insider of the Company.
    
    AND WHEREAS the Company wishes to maintain the continued services of and to
provide incentive to the Optionee and to this end is desirous of granting to 
the Optionee an option to purchase shares in the capital of the Company 
subject to the terms and conditions hereinafter contained.

NOW THEREFORE THIS AGREEMENT WITNESSETH:

DEFINITION

1.  In this Agreement the term "share" or "shares" means, as the case may be,
    one or more communion shares without par value in the capital stock of 
    the Company as constituted at the date of this Agreement.

GRANTING OF OPTION

2.  The Company hereby irrevocably grants to the Optionee, being an Insider   
    of the Company, a non-assignable, non-transferable option to purchase     
    100,000 shares in the

<PAGE>

    capital stock of the Company (hereinafter called the "Option") at $1.20 
    per share (the "Option Price") on the terms and conditions hereinafter 
    set forth.
    
EXERCISE OF OPTION

3.  The Option, may be exercised by the Optionee over a period of five (5) years
    until April 24, 2000, by notice in writing to the Company to that 
    effect. Any such notice given to the Company (an "Exercise Notice") shall 
    specify the number of shares with respect to which the Option is being 
    exercised and shall be accompanied by a cheque drawn on a Canadian 
    chartered bank in favor of the Company in full payment of the Option 
    Price for the number of shares then being purchased.

DELIVER OF SHARE CERTIFICATE

4.  The Company shall, within five business days after receipt of the Exercise
    Notice deliver to the Optionee: a share certificate representing the number 
    of shares with respect to which the Option is exercised and issued as of 
    the date of the Exercise Notice.
    
5.  An Exercise Notice shall be deemed to have been given, if delivered, on the
    date of delivery, or if mailed, on the date of mailing. A mailed Exercise 
    Notice shall be sent by prepaid registered mail addressed to the Company 
    at its Vancouver address.
    
OPTION ONLY

6.  Nothing herein contained or done pursuant hereto shall obligate the       
    Optionee to purchase and/or pay for any shares of the Company, except     
    those shares in respect of which the Optionee shall have exercised all or 
    any part of the Option granted hereunder.
    
7.  The Optionee shall have no rights whatsoever as a shareholder in respect to
    any of the shares optioned hereunder other than in respect of optioned 
    shares upon which the Optionee shall Lave exercised all or any part of the 
    Option granted hereunder and which shall have been taken up and paid for 
    in full.

APPROVAL

8.  The Option granted hereunder is subject to approval by ordinary resolution
    of the members of the Company entitled to vote at a general meeting of 
    the Company, passed prior to the exercise of the Option or any part 
    thereof.
    
FILING WITH REGULATORY AUTHORITIES

9.  This Agreement may be required to be filed with some or all of the
    Superintendent of Brokers for the Province of British Columbia and the 
    Vancouver Stock Exchange ("VSE") (collectively the "Regulatory 
    Authorities") and the Option hereby agrees to be bound by any 
    modification of the terms and conditions of the Option as may required by 
    the said Regulatory Authorities.


<PAGE>

10. A Declaration of Stock Option Position as attached hereto as "Schedule A"
    to this Agreement, is required by the VSE and the Optionee hereby agrees to 
    be bound by any modification of the terms and conditions of the Option as 
    may be required by the said Regulatory Authorities.
    
CAPITAL REORGANIZATION

11. In the event the authorized capital of the Company as presently constituted
    is consolidated into a lessor number of shares or subdivided into a 
    greater number of shares, the number of shares in respect of which the 
    Option remains unexercised shall be decreased or increased 
    proportionately as the case may be, and the then prevailing purchase 
    price to be paid by the Optionee for each such share shall be 
    correspondingly decreased or increased as applicable. In the event the 
    Company shall determine to amalgamate or merge with any other company or 
    companies (and the right to do so is hereby expressly reserved) whether 
    by way of statutory amalgamation, sale of its assets and undertaking, or 
    otherwise howsoever, then and in each such event the number of shares in 
    the corporation resulting from such amalgamation or merger in respect of 
    which the Option remains unexercised shall be such number of shares in 
    that corporation as would have been acquired by the Optionee pursuant to 
    the amalgamation or merger had the Option been fully exercised immediately 
    prior to the date of such amalgamation or merger and the then prevailing  
    purchase price of the shares to be paid by the Optionee shall be          
    correspondingly decreased or increased as applicable. 

TERMINATION OF OPTION

12. The Option is not assignable or transferable and shall terminate on the   
    30th day following the date upon which the Optionee ceases to be an       
    Insider of the Company; provided, however, that if such cessation is due  
    to the death of the Optionee, the personal representative of the Optionee 
    shall have the right to exercise any unexercised part of the Option for a 
    period of one year following the date of death of the Optionee. 

AMENDMENT OF MATERIAL TERMS

13. Any amendment to the Option is subject to approval by ordinary resolution
    of the members of the Company entitled to vote at a general meeting of 
    the Company.

TIME OF THE ESSENCE

14. Time shall be of the essence of this Agreement.

<PAGE>

SUCCESSORS

15. This Agreement shall enure to the benefit of and be binding upon the
    heirs, executors and administrators of the Optionee and the successors 
    of the Company.

IN WITNESS WHEREOF the parties hereto have caused these presents to be
executed as at the day and year first above written.

The Corporate Seal of SUMMO           )
MINERALS CORPORATION was              )
hereunto affixed in                   )
presence of:                          )
                                      )
                                      )              C/S
/s/ [Illegible]                       )
----------------------------          )
Authorized Signatory                  )
                                      )
                                      )
/s/ [Illegible]                       )
----------------------------          )
Authorized Signatory                  )



SIGNED, SEALED AND DELIVERED          )
by the Optionee in the presence of:   )
                                      )
Name: /s/ Judith L. Prescott          )      /s/ Robert A. Prescott
      -----------------------------   )      ----------------------------
                                      )      ROBERT A. PRESCOTT
Address: 1587 Bermuda Dunes           )
         --------------------------   )
         Boulder City, Nevada         )
         --------------------------   )
                                      )
Occupation: Housewife                 )
            -----------------------   )

<PAGE>


                                SCHEDULE"A"


                    DECLARATION OF STOCK OPTION POSITION
                    THIS FORM FOR COMPLETION BY OPTIONEE

RE: 
    --------------------------------------------------
               (Name of Company)

RE:                     incentive stock options in
    -------------------                            ----------------------
      (No. of options)                                    (Company)

I, ___________________, HEREBY CERTIFY that the aforesaid non-transferable 
options have been granted to me in compliance with the requirements of the 
V.S.E. Policy 23: and more particularly that at the time of grant, I was not 
aware of any change in the affairs of the Company which might have affected 
the trading price and had not been disclosed to the public. If the company 
is classified as a Venture Company as of the date of this declaration, I 
confirm that I have not been granted a stock option in the said Company 
within 2 years of the date of grant of the above-stated options.

I HEREBY FURTHER CERTIFY (complete either Part I or Part II as applicable):

                                   PART I

THAT I have not been granted any director or employee incentive share options 
by any other listed companies.

DATED the       day of                , 19  . SIGNATURE: 
          -----        --------------     --             -------------------

                                  PART II

THAT I hold as of the date of this Declaration existing incentive share 
options which have been granted to me by the above named company or other 
listed companies as follows:


                                                                  Outstanding
Name of                 No. of                Date of             Balance as
Listed                  Shares                Exercise            at Date of
Co.                     Optioned              Grant               Certificate


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

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

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

(Complete on separate sheet if insufficient space)

DATED the       day of                , 19  . SIGNATURE: 
          -----        --------------     --             -------------------