Port Radium Mine

"The Port Radium mine of Eldorado Mining and Refining Limited lies on the western tip of a large peninsula midway up the east shore of McTavish Arm, Great Bear Lake, about 30 miles south of the Arctic Circle. The mine is serviced by air, 950 miles from Edmonton, and by water, 1,380 miles from Waterways, Alberta.The veins were found, and the copper and cobalt minerals in them reported, by J. MacJntosh Bell of the Geological Survey of Canada in 1899. The veins were investigated by Gilbert Labine and E. C. St. Paul in 1930, and as a result of their work the Eldorado mine was brought into production in 1934. It produced silver and radium ores until 1940, at which time, as the silver orebodies had been mined out and the market for radium was negligible, it closed down. Early in World War II the need for uranium for the Manhattan Project was emphasized, and the mine was reopened in 1942. As a security measure Eldorado Mining and Refining was created a Crown company in 1944. The Port Radium mine has continued to be one of Canada's principal producers of pitchblende concentrates, and to date has about 25 miles of underground workings developed on fourteen levels.Regional GeologyThe general geology of the McTavish Arm area was mapped by D. F. Kidd in 1932 on a scale of one inch to four miles. A great deal of more detailed work has since been done by geologists of the Geological Survey and of Eldorado. The entire area at the end of McTavish Arm lies within the Precambrian Shield immediately east of its western margin. Most of the area is underlain by granitic masses which have intruded a sequence of late Precambrian sediments, volcanics, and hypabyssal intrusives. The pre-granite rocks now occur in extensive, irregular patches and pendants within the granite. Pitchblende deposits have been found in the district in all rock types, but the most favourable host rocks are the cherty sediments of the lower Echo Bay group."