Osisko Mining Corporation
TSX : OSK
FRANKFURT : EWX

Osisko Mining Corporation

December 06, 2006 13:40 ET

Osisko Releases Inferred Resource Estimate for Canadian Malartic

MONTREAL, QUEBEC--(CCNMatthews - Dec. 6, 2006) - Osisko Exploration Ltd.(TSX VENTURE:OSK) (FRANKFURT:EWX) is very pleased to announce the first National Instrument 43-101 compliant, inferred resource estimate from its 100%-owned Canadian Malartic deposit, located in the Abitibi region of Quebec. RSG Global Consulting Pty Ltd. of Perth, Australia ("RSG Global") has authorized Osisko to release results of their inferred resource estimate on the main portion of the Canadian Malartic gold deposit. Based on a lower cutoff grade of 0.5 g/t Au and using various statistical approaches, RSG Global has estimated an inferred resource between 6.54 and 6.59 million ounces gold. The tables below summarize results of the estimates using two different cutoff grades:



Inferred resource estimate, 0.5 g/t Au lower cutoff

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Geotatistical Metric tonnes (t) Grade (Au g/t) Au (Moz)
method

Multiple
Indicator
Kriging 178,404,000 1.14 6.539

Ordinary Kriging 177,188,000 1.15 6.551

Inverse Distance
Squared 170,806,000 1.20 6.590
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Inferred resource estimate, 1.0 g/t Au lower cutoff

----------------------------------------------------------------

Geostatistical Metric tonnes (t) Grade (Au g/t) Au (Moz)
method

Multiple
Indicator
Kriging 85,871,000 1.59 4.390

Ordinary Kriging 84,492,000 1.62 4.401

Inverse Distance 85,596,000 1.67 4.596
Squared
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Sean Roosen, President of Osisko, commented: "We are extremely pleased with these results, which suggest that the Canadian Malartic deposit is considerably larger than we had anticipated. This preliminary estimate included a 50 metre projection into the Sladen Extension, which we now know extends for at least an additional 240 metres along strike. The Sladen Extension, the Barnat South Zone, as well as additional drilling to the south will be the foundation for positive inferred resource updates in 2007. Furthermore, our 30-metre infill drill program, which recently started with Phase Eight drilling, will serve to upgrade the resource to measured/indicated status. Osisko shareholders can look forward to a very positive year in 2007 as the Company continues to explore and develop this exceptional gold deposit".

To date Osisko has completed over 60,000 metres of drilling on the Canadian Malartic property, part of a larger 75,000 metre definition drilling program slated to be completed by year end. The Canadian Malartic gold deposit is being evaluated for large-scale open pit, bulk-tonnage mining potential. Metallurgical test work is also in progress with results expected to be available early in the new year. The complete NI 43-101 compliant report will be filed on SEDAR as soon as it is made available to the Company by RSG Global.

Mr. Brett Gossage (MAusIMM) and Neil Inwood (MAusIMM) of RSG Global are independent Qualified Persons in accordance with National Instrument 43-101 and are responsible for the information presented in this news release. RSG Global is an international mining and exploration consulting firm with operational experience throughout the world. RSG Global has contributed to a large number of feasibility studies, due diligence or technical reviews and audits. Particularly relevant to the Canadian Malartic audit is RSG Global's experience in resource estimation of large open pit deposits by non-linear methods such as uniform conditioning, conditional simulation and multiple indicator kriging. This includes estimation studies completed on Rosia Montana, Lero Gold, Hidden Valley, Essakan, Youga, Boddington and other gold deposits.

Notes on the calculation of the inferred resource estimates:

- The database comprised a total of 244,271 metres of drilling and 172,803 gold assays, obtained from historical drilling and from approximately 41,720 metres of drilling completed by Osisko as of the end of August 2006.

- The mineralized envelope was modeled into a wireframe solid, which included a 50 metre zone of influence east of the deposit. Approximate dimensions of the envelope were 1470 metres in length (east-west), 460 to 850 metres in width, to a maximum vertical depth of 620 metres. Approximately 88% of the envelope occurs above the 350 metre level.

- Underground stopes and drives (as supplied by Osisko) were modeled into a wireframe solid, were treated as voids and removed from the model.

- Estimates are based on a Parent Cell dimension of 30 metres E, 20 metres N and 10 metres height.

- Calculations are based on 3 metre composites cut to a maximum of 25 g/t Au.

- All composites touching underground stopes were discarded.

- Tonnage estimates are based on densities of 2.68 tonnes/cubic metre for the porphyry and 2.75 tonnes/cubic metre for the sediments. Densities in three modeled high-grade zones were depleted to 2.5 tonnes/cubic metre to compensate for unidentified voids.

- Potential positive bias of approximately 20% exists in the historical Canadian Malartic Mines data base. Historical assay data will have to be tested and validated in order to upgrade the classification of the resource estimate.

The quantities and grades reported above are preliminary in nature and there has been insufficient work to date to define a NI 43-101 compliant measured/indicated mineral resource on the property. Furthermore, it is uncertain if additional work will result in the definition of an economic mineral reserve on the property. Mr. Robert Wares, P. Geo. and Executive Vice-President of Osisko, is the internal Qualified Person responsible for this news release.

Contact Information

  • Osisko Exploration Ltd.
    John Burzynski
    Vice-President Corporate Development
    514-735-7131
    Toll Free: 1-866-580-8891
    or
    Osisko Exploration Ltd.
    Daniel Boase
    Investor Relations
    416-742-5600
    Toll Free: 1-866-580-8891
    www.osisko.com