Copper deposits at the Rush and Brown mine and Venus prospect, Prince of Wales Island, southeastern Alaska

Abstract

The Rush and Brown mine and the Venus prospect are near the head of Kasaan Bay about 10 miles northwest of the village of Kasaan and about 45 miles northwest of Ketchikan, the nearest port. (See fig. 1.) They are in an area of moderate relief in in which some hills are a little more than 500 feet high. Much of the area is covered with glacial drift and dense vegetation. Muskegs are numerous. Outcrops are scarce and are confined mostly to steep slopes, stream beds, and places where development work has been done on the ore deposits. Topographic, geologic, and magnetic surveys of the vicinities of the ore deposits were made by the Geological Survey in 1943, and a brief examination of a portion of the underground workings at the Rush and Brown mine was made in 1944. The area is underlain principally by greenstone which has been intruded by bodies of pyroxenite, gabbro, and diorite. Foliation in the greenstone is obscure. post of the intrusive bodies trend northwesterly. The principal ore deposits are veins containing chiefly pyrite, chalcopyrite, and pyrrhotite. A few deposits of copper-bearing magnetite have been found. Most of these are small, but a larger one at the Rush and Brown mine has been mined for its copper and precious metals.