Cracroft Island is located near the boundary between the Coast Crystalline Belt and the Insular Belt. The island is underlain by lava, breccia and tuff of the Upper Triassic Vancouver Group, Karmutsen Formation, which has undergone regional greenschist facies metamorphism.

The occurrence is in a 330 degree trending shear zone in which chlorite and epidote alteration are present. Lenses of massive chalcopyrite and associated copper sulfate oxidation, assumed to be the mineral chalcanthite, occur in the shear zone. Disseminated chalcopyrite is also present over a width of 0.5 metres. Thin stringers of chalcocite are reported.

A sample of sorted ore from the dump at the adit assayed 0.5 per cent copper, trace silver and trace gold (Minister of Mines Annual Report 1926, page 313).

In 1901 the property consisted of the Welcome Home mineral claim. A prospect hole and a 12-metre shaft was sunk on the claim. In about 1916 Cracroft Copper Mines Limited acquired the property from the Fife Brothers of Port Neville. An adit was driven at that time. In May 1926, H.E. Rines restaked the claim, but no work was done.