Osisko Commences Subsequent Acquisition Transaction to Acquire Remaining Shares of Brett

MONTREAL, QUEBEC -- (Marketwire) -- 07/13/10 -- Osisko Mining Corporation ('Osisko') (TSX: OSK) (FRANKFURT: EWX) and Brett Resources Inc. ('Brett') (TSX VENTURE: BBR) (FRANKFURT: A4N) are pleased to announce that they have commenced the necessary steps to allow Osisko to acquire all of the remaining common shares of Brett that it does not currently hold. In order for Brett to become a wholly-owned subsidiary of Osisko, the two companies have entered into an arrangement agreement pursuant to which they intend to complete a business combination by way of a statutory plan of arrangement (the 'Arrangement') under the Business Corporations Act (British Columbia).

Osisko currently owns a total of 88,294,547 common shares of Brett ('Brett Shares'), representing approximately 77.2% of the issued and outstanding Brett Shares, which were acquired under its offer for all of the issued and outstanding Brett Shares dated April 13, 2010 (the 'Offer'). The proposed Arrangement constitutes the subsequent acquisition transaction, as contemplated under the Offer, by which Osisko intends to acquire all of the remaining Brett Shares not already owned by Osisko.

The proposed Arrangement is expected to be completed in August 2010, and is subject to certain conditions including receipt of all necessary court, shareholder and regulatory approvals, including approval of the TSX Venture Exchange. A special meeting of shareholders of Brett (the 'Meeting') has been called on August 11, 2010 to approve the Arrangement. The record date for determining the Brett shareholders entitled to receive notice of and vote at the Meeting was July 9, 2010. At least 662/3% of the votes cast by Brett shareholders at the Meeting must be in favour of the Arrangement to approve the Arrangement. As a result of the number of Brett Shares that Osisko acquired under the Offer, Osisko holds a sufficient number of Brett Shares to pass all necessary shareholder resolutions to approve the Arrangement.

Under the terms of the Arrangement, each Brett shareholder will receive 0.34 Osisko common shares and $0.0001 in cash for each Brett Share held (the 'Exchange Ratio'). The Exchange Ratio is the same consideration that Osisko offered and paid under the Offer. Upon completion of the Arrangement, outstanding Brett options and warrants will be exchanged and adjusted for a corresponding number of options and warrants to acquire Osisko common shares in accordance with the terms of the Offer.

About Osisko Mining Corporation

Osisko Mining Corporation is currently developing the Canadian Malartic gold deposit and evaluating adjacent areas for a large-scale open pit, bulk-tonnage mining operation. The Canadian Malartic deposit currently represents one of the biggest gold reserves in Canada for a single deposit, and is still growing through ongoing drilling on new mineralized zones.

About Brett Resources Inc.

Brett Resources Inc. is a Canadian minerals exploration company whose primary mandate is the discovery, acquisition, and development of precious metals systems, with particular expertise in Canada and Latin America. Since 2006 Brett's primary focus has been the 100 percent owned Hammond Reef Gold Deposit in Ontario.

Forward-Looking Information

Certain statements contained in this press release may be deemed 'forward-looking statements'. All statements in this release, other than statements of historical fact, that address events or developments that Osisko and Brett expect to occur, are forward looking statements. Forward looking statements are statements that are not historical facts and are generally, but not always, identified by the words 'expects', 'plans', 'anticipates', 'believes', 'intends', 'estimates', 'projects', 'potential', 'scheduled' and similar expressions, or that events or conditions 'will', 'would', 'may', 'could' or 'should' occur. Although Osisko and Brett believe the expectations expressed in such forward-looking statements are based on reasonable assumptions, including, without limitation that all technical, economical and financial conditions will be met in order to put the Canadian Malartic Project and the Hammond Reef Gold Project into commercial production, such statements are not guarantees of future performance and actual results may differ materially from those in forward looking statements. Factors that could cause the actual results to differ materially from those in forward-looking statements include gold prices, access to skilled consultants, mining development and mill production personnel, results of exploration and development activities, Osisko and Brett's limited experience with production and development stage mining operations, uninsured risks, regulatory changes, defects in title, availability of personnel, materials and equipment, timeliness of government approvals, actual performance of facilities, equipment and processes relative to specifications and expectations, unanticipated environmental impacts on operations market prices, continued availability of capital and financing and general economic, market or business conditions. These factors are discussed in greater detail in Osisko and Brett's most recent Annual Information Forms, both of which are filed on SEDAR, which also provide additional general assumptions in connection with these statements. Osisko and Brett caution that the foregoing list of important factors is not exhaustive. Investors and others who base themselves on the forward-looking statements contained herein should carefully consider the above factors as well as the uncertainties they represent and the risk they entail. Osisko and Brett believe that the expectations reflected in those forward-looking statements are reasonable, but no assurance can be given that these expectations will prove to be correct and such forward-looking statements included in this press release should not be unduly relied upon. These statements speak only as of the date of this press release.

Contacts:

Osisko Mining Corporation

John Burzynski

Vice-President Corporate Development

416-363-8653


Osisko Mining Corporation

Sylvie Prud'homme

Manager, Investor Relations

514-735-7131

Toll Free: 1-888-674-7563


Brett Resources Inc.

Connie Norman

Corporate Secretary

604-488-0008