Mount Copper is estimated to host an inferred resource of 456 million tonnes of 0.351% copper. At 1.41 million tonnes (3.1 billion pounds) of contained copper, that amounts to the largest untapped copper resource in eastern North America, Osisko said in a press release, Thursday.
The estimate is pit-constrained to mineralization surrounding the past-producing Mount Copper open pit mine (Mount Copper Expansion Project). It is based on historical drilling completed between the 1960s and 2019.
Thursday’s announcement comes just weeks after Osisko said it has signed a binding term sheet with Glencore Canada Corp. that gives it the right to earn a 100% interest in Gaspe Copper, which is located near Murdochville, Quebec.
Gaspe Copper (formally a subsidiary of Noranda) mined a porphyry copper/skarn complex and produced copper concentrate continuously from 1955 until the mine closed in 1999. During that period, 150 million tonnes of average grade 0.87% copper, with minor, molybdenum, gold and silver credits were extracted initially from the Needle Mountain and Mount Copper open pits.
That material was supplemented with feed from the extensive high-grade underground skarn mineralization and the massive sulphide skarn and manto underground deposits.
Osisko said it has developed an internal model that suggests there is a strong economic case for re-opening Gaspe Copper. It is aiming to test that assumption by focusing initially on the remnant mineralization in the existing pit. By drilling and re-evaluating the remaining resources, it has said it plans to validate the model and close the transaction with Glencore.
“We strongly believe this large-scale asset could become a core component of Quebec’s critical mineral development strategy that aims to provide essential metals for global decarbonization initiatives,’’ said Osisko Chairman and CEO Robert Wares.
“Our 30,000-metre drill program has begun with the objective of refining sulfide/oxide ratios in the deposit and upgrading the mineral resource estimate to measured and indicated categories by year-end,’’ he said.
“Furthermore, we will immediately launch a preliminary economic assessment (PEA) on the Mount Copper Expansion Project and look forward to rapidly developing the asset in partnership with Glencore Canada,’’
Osisko shares were unchanged at 56 cents on volume of 148,450 and current trade in a 52-week range of 69 cents and 35 cents.
Osisko Metals, which is affiliated with Osisko Gold Royalties Ltd. (OR-TSX, OR-NYSE), is a Canadian exploration and development company with a previous focus on zinc. Its asset portfolio includes Pine Point project in the Northwest Territories and the Bathurst Mining Camp properties in northern New Brunswick.
According to a 2020 preliminary economic assessment (PEA) the Pine Point project contains resources that are amenable to open pit and shallow underground development, consisting of an indicated resource of 12.9 million tonnes, grading 6.29% zinc equivalent. On top of that is an inferred resource of 37.6 million tonnes grading 6.80% zinc equivalent.