VIA COURIER AND FAX 1-604-632-4678
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June 14, 2004


Dr. Mark O'Dea
President & CEO
Fronteer Development Group Inc.
1640- 1066 West Hastings Street
Vancouver, BC
V6E 3X1, Canada

Dear Mark:

RE:  JOINT FRONTEER-NWT 2004 EXPLORATION COMMITMENTS

This letter will serve to amend the September 26, 2003 Option Agreement ("Option
Agreement") and the December 17, 2003 and January 30, 2004 Amending Agreements,
thereto, entered into between Fronteer Development Group ("Fronteer") and
Northwestern Mineral Ventures Inc. ("NWT") with respect to the Achook, McPhoo,
Conjuror, and Longtom Properties (the "Bear Properties").

1.   We confirm that by way of a letter dated May 25, 2004, Fronteer and NWT
     have agreed to include the Longtom Property as an "after acquired property"
     in the aforesaid Option Agreement.

2.   We confirm that Fronteer has identified the Longtom Property as the primary
     target of drilling and exploration activities for the 2004 season.

3.   Fronteer and NWT will jointly and equally fund a drilling and exploration
     budget of CDN $1.0 million on the Longtom Property for the 2004 season. For
     greater clarity, NWT will fund $500,000 of drilling and exploration
     activities on the Longtom Property for the 2004 season, while Fronteer will
     fund the other $500,000 of drilling and exploration activities. See
     attached Schedule "A" for the Joint Fronteer-NWT Exploration Budget for
     2004.



4.   Fronteer agrees to incur the first $500,000 of drilling and exploration
     costs, while NWT will incur the second $500,000 of drilling and exploration
     costs on the Longtom Property for the 2004 season so that NWT has
     sufficient time to close a minimum $500,000 flow-through financing.

5.   NWT will forthwith transfer the funds of $500,000 to the law firm of Beach,
     Hepburn, IN TRUST (the "Trust Funds"). The Trust Funds will remain in
     trust, with the condition that the funds will be returned to NWT's treasury
     if it successfully completes a minimum of $500,000 flow-through financing
     by August 1, 2004. If NWT does not complete its minimum $500,000
     flow-through financing by August 1, 2004, Fronteer will then be able to
     make cash calls against the Trust Funds in satisfaction of NWT's drilling
     and exploration commitments on the Longtom Property as per the Joint
     Fronteer-NWT Exploration Budget for 2004.

6.   NWT's obligation to fund any further exploration activities pursuant to the
     Option Agreement, and including the 2005 exploration season, shall be
     within the discretion of NWT's management, and the decision to participate
     in the 2005 exploration season shall be based on the results of the 2004
     drilling and exploration activities.

7.   Subject to the above amendments, the Option Agreement and the December 17,
     2003 and January 30, 2004 Amending Agreements, read together, remain
     unchanged.

If Fronteer is in agreement with the above, please execute a copy of this letter
in the space provided and return the executed letter to Northwestern Mineral
Ventures Inc.


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                                    Sincerely,

                                    NORTHWESTERN MINERAL VENTURES INC.
                                    Per:

                                    /s/ Kabir Ahmed


                                    Kabir Ahmed
                                    President & CEO

                                    ACKNOWLEDGEMENT

                                    Fronteer Development Group Inc. agrees to
                                    the above matters as stated in this herein
                                    letter dated 14 June, 2004.

                                    Dated the 14 day of June, 2004.

                                    FRONTEER DEVELOPMENT GROUP INC.
                                    Per:


                                    /s/ Mark O'Dea
                                    -----------------------------
                                    DR. MARK O'DEA President & CEO
                                    I have the authority to bind the
                                    corporation.










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