Osisko and EMSE Sign Agreement for Development of Famatina Project in Argentina

MONTREAL, QUEBEC--(Marketwire - Aug. 31, 2011) - Osisko Mining Corporation (the "Corporation" or "Osisko") (TSX:OSK)(FRANKFURT:EWX) and Energía y Minerales Sociedad Del Estado ("EMSE"), the La Rioja state mining corporation, are pleased to announce that they have entered into a binding agreement regarding the development of the Famatina gold project ("Famatina" or the "Project") in La Rioja Province, Argentina. The Famatina project area covers a 40 square kilometre zone hosting various gold-enriched epithermal and porphyry targets.Terms of the agreement include:

• US$500,000 cash payment to EMSE within 15 days of signing the agreement
  
  
• A first-year US$10M commitment in exploration expenditures during the initial 4 years term ("Initial Term") of the Agreement
  
  
• Osisko may earn a 70% interest in the Project by completing a feasibility study within the Initial Term, as said Initial Term may be extended at Osisko's discretion for an additional term of 4 years if required to complete said feasibility study
  
  
• Osisko commits to financing 100% of the Project's development and construction costs, with repayment of EMSE's portion from 25% of its attributable project cash flows
  
  
• EMSE will be responsible for gaining all required permits throughout the life of the Project
  
  

The Famatina Project is characterized by intense hydrothermal alteration produced by a number of Upper Miocene dacite porphyry stocks intruding low grade, metamorphic sedimentary (Cambrian-Ordovician) and granitic rocks (Ordovician). Known mineral occurrences include at least five Cu-Mo-Au porphyries, three associated gold epithermal high sulfidation systems and one higher grade structurally controlled epithermal vein system. None of the mineral systems at Famatina currently have NI 43-101 compliant resources.

Mr. Sean Roosen, President and Chief Executive Officer of Osisko stated: "In Famatina, Osisko has identified an ideal project with which to enter one of the best mining jurisdictions in South America. We are very excited at the addition of another high quality project to our current portfolio of properties. We believe Famatina hosts very promising targets with excellent potential for future development. We have assembled a highly experienced team to oversee the work and we look forward to an intensive exploration program on the property over the coming year."

About Osisko Mining Corporation

Osisko Mining Corporation operates the Canadian Malartic Gold Mine in Malartic, Quebec and is aggressively pursuing resource definition on the Hammond Reef Gold Project in Northern Ontario, as well as exploration on a number of additional properties in Canada.