Canadian Mining Journal


COPPER: Midland, Osisko Mining find high grade boulder field in James Bay region

This sample of a diorite boulder with disseminated chalcopyrite returned 4.54% copper and 5.1 g/t silver. (Credit: Midland Exploration)

QUEBEC – The joint venture of Midland Exploration of Montreal and Toronto’s Osisko Mining announced the discovery of a high grade copper boulder field with grades as high as 8.28% copper. The find was made in the James Bay region, northwest of the Eleonore gold mine and southeast of the Cheechoo gold project.

The area of interest is in the southern part of the property. Four diorite boulders were tested in 2016-17, returning  8.28%, 6.85%, 4.54% and 3.45% copper in grab samples. Mineralization consists of disseminated chalcopyrite ribbons in the boulders. The geochemical signature of the boulders and the host rock suggest a porphyry copper system, said Midland.

The team also delineated an anomalous area 600 x 100 metres of gold hosted amphibolites. Twelve samples of amphibolite in disseminated pyrrhotite, pyrite and chalcopyrite returned >0.1 g/t gold, and the best one assayed 0.82 g/t gold.

“This type of low grade mineralized halo is common around orogenic gold deposits. The gold-anomalous amphibolites are located near the prolific contact between the geological subprovinces of La Grande and Opinaca. This contact hosts most of the important gold deposits and showings in the area, such as the Eleonore mine and the Cheechoo prospect, located about 30 kilometers northwest of this area,” said Midland in a release.

More information about the Midland-Osisko joint venture is posted at