Osisko Mining Corporation
TSX : OSK
FRANKFURT : EWX

Osisko Mining Corporation

September 08, 2005 16:06 ET

Osisko Outlines Gold Potential at Malartic

MONTREAL, QUEBEC--(CCNMatthews - Sept. 8, 2005) - Osisko Exploration Ltd. (TSX VENTURE:OSK)(DEUTSCHE BOERSE:EWX) is pleased to announce that data compilation on its 100%-owned Canadian Malartic property has outlined a gold mineralized system that offers a potential for approximately 100 million metric tons grading between 1.00 g/t and 1.35 g/t Au, yielding a potential resource of 3.2 to 4.3 million ounces gold. The potential quantities and grades reported above are conceptual in nature and there has been insufficient work to date to define a NI 43-101 compliant mineral resource on the property. Furthermore, it is uncertain if additional exploration will result in discovery of an economic mineral resource on the property.

The deposit is an Archean porphyry gold system, consisting of a widespread shell of disseminated gold and pyrite mineralization hosted by diorite porphyry and altered metasediments. The potential deposit referred to above is based on compilation of data from over 5000 historical surface and underground holes and of twenty-two holes drilled to date by Osisko. Geological modeling of the deposit along 20 vertical sections spaced 60 metres apart indicates that the mineralized system is 1200 metres long by 350 metres wide, with a variable true thickness ranging from 60 to 270 metres to a vertical depth of 320 metres from surface. Average grade of the mineralized body is estimated to lie between 1.00 g/t and 1.35 g/t Au, based on a weighted average of 1.17 g/t Au from analyses of holes drilled by Osisko and applying a 15% margin of error. The potential tonnage of approximately 100 million metric tonnes has been calculated assuming an average true thickness of 90 metres and an average rock density of 2.65 tonnes per cubic metre. The mineralized system is open to the west and to the south at depth.

The above-quoted figures are reported as an exploration target, based on reasonable assumptions made from compiled data. These figures should not be construed to reflect a calculated resource (inferred, indicated or measured) under standards of National Instrument 43-101.

Management believes that the Canadian Malartic project offers potential for a near surface gold deposit located near existing infrastructure, which may ultimately be evaluated as an open pit, bulk tonnage mine. Osisko will maintain the current drill program on the property to the end of 2005 with the objective of calculating and releasing a NI 43-101 compliant, inferred gold resource by early 2006.

Mr. Robert Wares, P. Geo. and President of Osisko, is the Qualified Person responsible for the preparation of this news release.

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