ROSS
RIVER MINERALS INC.

December 21, 2004

Almaden Minerals Ltd. and Minera
Gavilan S.A. de C.V. 1103 - 750 West Pender Street Vancouver, British Columbia
V6C 2T7

Attention: Duane Poliquin, President

Dear Sirs:

RE:El Pulpo property (the “El Pulpo
Property”) as described in Schedule “A” to the option agreement dated for
reference the 10th day of April 2003 (the “Option Agreement”) made between
Almaden Minerals Ltd. and Mineral Gavilan S.A. de C.V.(collectively “Almaden”)
and Ross River Minerals Inc. (“Ross River”)

Further to our recent discussions
and our letter to you of October 18, 2004, the Board of Ross River has
authorised me to make the following revised offer:

1.
    Ross River will
      acquire all of the right, title and interest of Almaden in the El Pulpo
      Property and in the underlying agreements, concessions and additional
      mineral and property interests related thereto acquired since the date of
      the Option Agreement, all of which such agreements and interests, together
      with the El Pulpo Property, are more particularly described in Exhibit “A”
      attached hereto and are hereinafter collectively referred to as the
      “Property”.2.
    Ross River
      (and/or its Mexican subsidiary, Minera Rio Ross S.A. de C.V.) hereby
      agrees to acquire 100% of the right, title and interest of Almaden in the
      Property, in consideration of which Ross River will issue a total of four
      million two hundred thousand (4.2 million) shares of Ross River and grant
      a 2% net smelter returns royalty to Almaden (the “Purchase Price”) on the
      basis set forth in paragraph 3 hereof.3.
    Ross River will
      pay the Purchase Price to Almaden Minerals Ltd. and Minera Gavilan S.A de
      C.V. (“Minera Gavilan”) as follows:


Suite
1004 - 750 West Pender St., Vancouver, BC, Canada V6C 2T7 Tel: (604) 682-2770
Fax: (604) 682-2331 www.rossriverminerals.com




(a)
    2.2 million shares of Ross River to
      Almaden Minerals Ltd. on the Closing Date (as defined in paragraph 4
      hereof);(b)
    if exploration
      and development expenditures on the Property meet or exceed US$10 million,
      including expenditures incurred to date, then Ross River will issue one
      million shares to Almaden Minerals Ltd.;(c)
    issue one
      million shares of Ross River to Almaden Minerals Ltd. on delivery of a
      positive bankable feasibility study (the “Feasibility Study”) recommending
      commercial production on any part of the Property; and(d)
    grant a royalty
      to Minera Gavilan equal to 2% of net smelter returns (the “Royalty”), such
      Royalty to conform to generally accepted industry standards, regarding any
      minerals removed from the Gavilan, Gavilan II and Gavilan 3 concessions
      (the "Concessions") provided that Minera Gavilan hereby grants to Ross
      River the exclusive right to purchase, not earlier than 30 days but prior
      to 120 days after the date on which Ross River gives notice to Minera
      Gavilan that a decision has been made to place all or any part of the
      Concessions into commercial production, one half of the Royalty (such that
      the Royalty would be reduced to 1% of net smelter returns) for
      consideration equal to the fair market value of the 1% royalty based upon
      the feasibility study, such value to be determined by an internationally
      recognised engineering firm mutually acceptable to both parties. In the
      event of a dispute between the parties regarding the Royalty, such dispute
      shall be adjudicated in accordance with the Commercial Arbitration Act
      (British Columbia). For greater certainty, in the event that Ross River
      intends to place more that one mine into production on the Property, the
      Royalty and the right to purchase half the Royalty would apply to each
      such mine at the commencement of commercial production.4.
    The
      completion of the purchase and sale contemplated herein (the
      “Transaction”) shall be on or before the tenth business day (the “Closing
      Date”) following the receipt by Ross River of:(a)
    approval of the
      TSX Venture Exchange;(b)
    transfers in
      registrable form, satisfactory to Ross River, regarding the conveyance,
      assignment and sale of 100% of the Property from Almaden to Ross
      River;(c)
    such further
      documents, agreements, consents and approvals as may reasonably be
      required by Ross River to give effect to the
Transaction.


Suite
1004 - 750 West Pender St., Vancouver, BC, Canada V6C 2T7 Tel: (604) 682-2770
Fax: (604) 682-2331 www.rossriverminerals.com




5.
    On the Closing
      Date, Ross River will deliver to Almaden (against receipt of the transfers
      and further documents referred to in subparagraph 4(b) and (c) hereof) a
      certificate registered in the name of Almaden Minerals Ltd. representing
      2.2 million common shares of Ross River and notice of registration of the
      Royalty to Minera Gavilan with the appropriate Mexican Authorities. The
      shares will be subject to a four month hold period.6.
    Almaden and
      Ross River agree that from the date of acceptance hereof by Almaden until
      the expiry of two years from the Closing Date, Almaden will not acquire
      any interest in (or enter into any additional agreements regarding),
      concessions or mineral and property interests located within ten
      kilometres of the outer boundary of the Property (as defined in paragraph
      1 hereof).7.
    After the
      Closing Date, Ross River shall have the right to transfer all or a portion
      of the Property, subject to the Royalty, to any arms length third party
      without the consent of Almaden provided that with respect only to that
      portion of the Property identified in red on Exhibit "B", Ross River
      acknowledges that it will not enter into any agreement with a third party
      unless such party possesses the financial capability and industry
      experience reasonably required to fulfill its obligations under such
      agreement.8.
    Almaden has
      relied on the information provided by Ross River to make this decision and
      Ross River confirms that it has provided Almaden with all pertinent
      information on the Property.9.
    This agreement
      will replace and supercede the option agreement dated April 10, 2003 and
      accordingly, on closing, the option agreement and all further obligations
      thereunder will be cancelled.


If you find the foregoing
acceptable, please indicate your consent and agreement by signing and returning
the enclosed copy of this letter to us, on receipt of which we will instruct our
counsel to prepare formal documentation.

Yours truly,

Ross River Minerals Inc.

“Marcus N. Foster”

Marcus N. Foster

President and Chief Executive
Officer

Suite
1004 - 750 West Pender St., Vancouver, BC, Canada V6C 2T7 Tel: (604) 682-2770
Fax: (604) 682-2331 www.rossriverminerals.com




We
      hereby consent and agree to the foregoing on behalf of Almaden Minerals
      Ltd. andMinera Gavilan
      S.A. de C.V.ALMADENMINERALSLTD.
    MINERAGAVILANS.A.DEC.V.“D. Poliquin”
    “D.
Poliquin”Per:
    Per:Authorised Signatory
    Authorised
Signatory


Suite
1004 - 750 West Pender St., Vancouver, BC, Canada V6C 2T7 Tel: (604) 682-2770
Fax: (604) 682-2331 www.rossriverminerals.com




EXHIBIT“A”PROPERTYDESCRIPTIONConcessions:
    (see
      attached maps)Claim
    File No.
    Title
      No.Gavilan
    Exp-95/11875
    216276Gavilan
      II
    Exp-95/11918
    217919Gavilan
      3
    Exp-95/12054
    PendingPolo
    Exp-95/9775
    207908Los
      Frailes
    Exp-95/11484
    212809Los
      Frailes
    Exp-95/9769
    207907
















EXHIBIT
“B”


CONCESSION AND OPTION
AREA

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