Columbium-Uranium Deposits at North Bay, Ontario
Discovered in 1952, the deposits have been explored by diamond drilling on and near a group of islands in lake Nipissing and from underground workings. The ore mineral is a uranian pyrochlore. It occurs in breccia zones in association with calcite, apatite, acmite, feldsiiars, biotite, magnetite, sulphides, and fluorite in varying amounts. The pyrochlore concentrations occur in a steeply-dipping gneiss series with some crystalline limestone. Trends indicate a ring structure 114 miles in diameter.