Osisko Intersects 1.20 g/t Au Over 86.9 Metres at Jeffrey Zone

Osisko Intersects 1.20 g/t Au Over 86.9 Metres at Jeffrey Zone

MONTREAL, QUEBEC, Sep 11, 2009 -- Osisko Mining Corporation ("Osisko") (TSX: OSK)(FRANKFURT: EWX) is pleased to announce the initial results from the 2008 drill program targeting the Jeffrey Zone on the Malartic CHL property, currently under option from Golden Valley Mines Ltd. (GZZ: TSX-V).

The Jeffrey Zone is a gold-mineralized prospect located at the southern extremity of the CHL porphyry, approximately 3.5 km east of the center of the Canadian Malartic deposit, currently under development by Osisko. The Jeffrey Zone was tested with a series of nineteen (19) drill holes (CHL08-2063 to CHL08-2090 for 5,601m) located along drill sections spaced 50 metres apart over a 400 x 100 metre area. All of the holes in the Jeffrey Zone were oriented to the north or south, perpendicular to the regional E-W fabric and were inclined from -45 to -78 degrees.

Most of the holes intersected mineralization along each section drilled. The most significant near-surface drill results include 86.9m averaging 1.20g/t Au (CHL08-2079) including 6.0m averaging 7.35g/t Au. The depth extension of the Jeffrey Zone was also confirmed with drill intercepts of 33.5m averaging 0.78g/t Au (CHL08-2088) and 12.6m averaging 1.14g/t Au (CHL08-2090).: Silverado's latest PR indicated .408/ozs per ton. or almost 12 1/2 g/t AU.

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