This data release provides electron microprobe analyses of ore minerals from the Copperwood sediment-hosted stratiform copper deposit in the Upper Peninsula of Michigan. The minerals include bornite, chalcocite, native copper, native silver, and pyrite. Minerals were analyzed for Ag, As, Co, Cu, Fe, Hg, Ni, Pb, S, Sb, and Zn. Results with acceptable totals that lie between 98.5 and 101.5% show that these minerals are stoichiometric, with very limited substitution of other elements.
The Copperwood copper deposit is a sediment-hosted stratiform copper deposit in the Presque Isle Syncline of the Upper Peninsula of Michigan. The Lower Copper Bearing Sequence has a 2018 mineral resource estimate of 42.2 million metric tons (Mt) of measured plus indicated mineral resources at an average grade of 1.60% Cu and 3.84 g/t Ag. The measured plus indicated mineral resource in the Upper Copper Bearing Sequence is estimated to be 7.1 Mt at an average grade of 1.21% Cu and 3.26 g/t Ag (Gignac, 2018). The mineral reserves for the Copperwood Project are estimated at 25.4 Mt at an average grade of 1.43% Cu and 3.83 g/t Ag (Gignac, 2018).