Gold in the Hardrock area was first discovered south of the Main Narrows of Kenogamisis Lake between 1916 and 1918. This was followed by a number of discoveries in the 1930s, including the Little Long Lac, MacLeod-Cockshutt, Hard Rock and Mosher mines. The Hardrock deposit was mined by the former Hard Rock, MacLeod-Cockshutt and Mosher companies between 1938 and 1970.
In the 1980s, Lac Minerals Ltd. (now Barrick Gold Corporation) undertook studies on the existing underground reserves at the MacLeod-Cockshutt and Hardrock mines. The company carried out lithogeochemical sampling, ground geophysical surveys and diamond drill programs focusing on targets with open pit potential. In 1992, Asarco Exploration Company of Canada Limited and then Cyprus Canada Inc. entered into a five-year earn-in agreement with Lac Minerals. The ensuing RC and diamond drilling programs resulted in a historical resource estimate for a number of pit areas and discovery of a new zone.
Premier Gold acquired the property in 2008 and carried out drilling on various targets in the Project area. The work resulted in a NI43-101 Mineral Resource estimate reported in 2010. In March 2014, a preliminary economic analysis (“PEA”) was prepared for the Project.
On March 9, 2015, Centerra Gold and Premier Gold Mines announced the formation of a 50/50 partnership TCP GP Corporation to explore and develop the Trans-Canada Property, including the Hardrock Project. On July 20, 2015, the board of TCP GP Corporation approved a name change, and Greenstone Gold Mines was formed.
In December 2016, Centerra Gold and Premier Gold Mines publish a NI43-101 Technical Report specific to the development of the Hardrock Project as an open pit mine. (2016 43-101 Technical Report)