The Granduc area has been explored for minerals since the initial mineralization discovery in 1931. The property was first staked in 1951 and by the early 1960’s mine development was underway. Newmont financed the development of the mine, which opened in 1970, with a 2000 tonne per day capacity; however processing capacity was increased during mining.
The mine operated from 1970 through until 1977, when it was shut down for approximately three years. The mine was acquired by Esso Minerals Canada in 1979 and operated from 1981 to May 1984 when it was decommissioned due to high costs and low copper prices. Mining methods included sublevel caving between 1970 and 1977 and slot and mass blasting during Esso’s operation of the mine. The mine processed approximately 15 million tonnes of ore and produced approximately 180,000 tonnes of copper over approximately 10 years of production. Average head-feed grade of approximately 1.29% copper and processing achieved 95% copper recovery. Average precious metal production included 0.13 g/t gold and 8 g/t silver. Copper concentrates were shipped from Stewart, BC to markets in Japan.
Exploration on the property between 1974 and 1984 focussed on extending the mineralized zones to the north and south of the main deposit. This lead to the discovery of the North Zone mineralization; approximately 1 km north of the Main Zone.
Short periods of exploration were completed after closure of the mine by Esso in 1984. This included two small surface exploration programs operated by Hecla Mining Company in 1991 and again 1993. Bell Copper acquired the rights to the property in 2005 and operated two exploration programs in 2005 and 2006. They conducted field exploration, airborne geophysics and diamond drill programs, dominantly focused on the North and South Zones along strike of the Main Granduc Zone. As well, Bell Copper targeted an area where massive sulphide boulders were identified by previous exploration, termed the JK Zone.
No further work was completed on the property until Castle Resources acquired it in 2010.