Osisko Reports November Production From Canadian Malartic Production of 33,102 Ounces of Gold in November

MONTREAL, QUEBEC -- (Marketwire) -- 12/10/12 -- Osisko Mining Corporation (the "Company" or "Osisko") (TSX: OSK)(FRANKFURT: EWX) is pleased to report November production statistics from its flagship Canadian Malartic Mine, listed below:

--  Monthly gold production of 33,102 ounces
--  Monthly mill throughput of 1,414,396 tonnes
--  Average daily throughput of 48,772 tonnes per operational day (based on
    29 days of operation)
--  Average grade milled of 0.815 g/t Au
--  Average recovery of 89.3%

Year-to-date average grade milled is 0.97 g/t Au. Year-to-date gold production is 356,476 ounces, and since commencement of milling operations in April 2011 556,614 ounces of gold have been produced from Canadian Malartic.

Throughput at the mill continues to improve, with combined October-November production averaging over 49,000 tonnes per operating day, up from the third quarter average of 43,181 tonnes per operating day. With the increase in average daily throughput, the Company is continuing to see improvement in costs per tonne milled. Third quarter average operating costs per tonne milled stood at $23.51. Interim cost per tonne milled for the month of October was $19.31 (unaudited and subject to revision). November interim cost per tonne milled is not yet available, but is expected to be higher than October due to lower throughput.

During the month of November, the mill ran at throughput rates of over 50,000 tonnes per day for 10 days. A new record one-day processing rate of 58,476 tonnes was achieved on November 4th. Throughputs of over 58,000 tonnes per day were achieved three days in a row by reducing the size of the feed produced by the secondary crushers. Of note, recoveries over these three days averaged over 89%.

The milling circuit was shut down on November 30th through to mid-day December 2nd to allow for the planned physical installation of the second XL1100 pebble crusher. At this time the first XL1100 pebble crusher was temporarily placed on bypass from the circuit to allow for the integration of the linked feed system (between the two pebble crushers) during the coming week. The remaining portion of this scheduled shut-down will occur in mid-December, at which time the remaining mill liner changes will be completed and the feed system will be reconnected to incorporate the two XL1100 pebble crushers to the line. The scheduled shutdown was split into two time periods to accommodate and avoid overlap with the numerous (150+) contractors involved in the crusher installation and liner change work. All work referred to above is expected to be completed within a planned total of seven days.

December Throughput Preview

The integration of the second XL1100 pebble crusher to the line completes the crushing modifications initiated earlier this year. With the completion of this work, daily throughputs at the mill are anticipated to continue improving towards design capacity. Following successful completion of the installation work and run-in of the new pebble crusher, the company expects to return to full operational guidance early in the New Year.

About Osisko Mining Corporation

Osisko Mining Corporation operates the Canadian Malartic gold mine in Malartic, Quebec and is pursuing exploration on a number of properties, including the Hammond Reef Gold Project in Northern Ontario.

Mr. Luc Lessard, Eng., Senior Vice-President and Chief Operating Officer of Osisko, is the Qualified Person who has reviewed this news release and is responsible for the technical information reported herein, including verification of the data disclosed.

Forward-Looking Statements

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 expects 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 including, without limitation, the timely and successful integration of the two XL1100 pebble crushers to the mill and the continued improvement of milling throughputs at the Canadian Malartic Mine. Although Osisko believes 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 timely and successfully integrate the two XL1100 pebble crushers to the mill and to continue to improve milling throughputs at Canadian Malartic, 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 construction personnel, results of exploration and development activities, Osisko's limited experience with production and mining operations, uninsured risks, regulatory framework and 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's most recent Annual Information Form and in the most recent Management Discussion and Analysis filed on SEDAR, which also provide additional general assumptions in connection with these statements. Osisko cautions that the foregoing list of important factors is not exhaustive. Investors and others who base themselves on forward-looking statements should carefully consider the above factors as well as the uncertainties they represent and the risk they entail. Osisko believes 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

Director of Investor Relations

(514) 735-7131

Toll Free: 1-888-674-7563
www.osisko.com