Exhibit 5.1

POWER OF ATTORNEY

I, Robert R. McEwen hereby appoint Stefan M. Spears my true and lawful attorney-in fact to:

(1) execute for me on my behalf, in my capacity as an individual and in my capacity as an officer, and/or director of US Gold Corporation and 2190303 Ontario Inc. (the “Companies”), Forms 3, 4, and 5 and Schedules 13D and 13G and any Amendments thereto, in accordance with Sections 13 and 16 of the Securities Exchange Act of 1934 and the rules thereunder (the “Securities Exchange Act”);

(2) do and perform any and all acts for me and on my behalf which may be necessary or desirable to complete and execute any such Forms 3, 4, or 5 and Schedules 13D and 13G and any Amendments thereto and timely file such Form, Schedule or Amendment with the United States Securities and Exchange Commission and any stock exchange or similar authority; and

(3) take any other action of any type whatsoever in connection with the foregoing which, in the opinion of the attorney-in-fact, may be of benefit to, in the best interest of, or legally required by me, it being understood that the documents executed by the attorney-in fact on my behalf pursuant to the Power of Attorney shall be in such form and shall contain such terms and conditions as the attorney-in-fact may approve in his discretion.

I hereby grant to such attorney-in-fact full power and authority to do and perform any and every act and thing whatsoever requisite, necessary, or proper to be done in the exercise of any of the rights and powers herein granted as fully to all intents and purposes as I might or could do if personally present, with full power of substitution or revocation, hereby ratifying and confirming all that the attorney-in-fact, or the attorney-in-fact’s substitute or substitutes, shall lawfully do or cause to be done by virtue of this Power of Attorney and the rights and powers herein granted. I hereby acknowledge that the foregoing attorney-in-fact, in serving in such capacity at my request, is not assuming, nor are the Companies assuming, any of my responsibilities to comply with Section 13 or 16 of the Securities Exchange Act of 1934.

This Power of Attorney shall remain in full force and effect until I am no longer required to file Forms 3, 4, 5 and Schedules 13D or 13G and any Amendments thereto, unless I earlier revoke this Power of Attorney in a signed writing delivered to the attorney-in-fact.