Uranium mining by country largest Canadian mines are located in the Athabasca Basin of northern Saskatchewan. Canada's first uranium discovery was in the Alona Bay area, south of Lake Superior Provincial Park in Ontario, by Dr. John Le Conte in 1847. The Canadian uranium industry, however, really began with the 1932 discovery of pitchblende at Port Radium, Northwest Territories. The deposit was mined from 1933 to 1940, for radium, silver, copper, and cobalt. The mine shut down in 1940, but was reopened in 1942 by Eldorado Mining and Refining Limited to supply uranium to the Manhattan Project. The Canadian government expropriated the Port Radium
Period 7 element corresponding to the filling of the 5f electron shell; actinium, a d-block element, is also generally considered an actinide. In comparison with the lanthanides, also mostly f-block elements, the actinides show much more variable valence. Of the actinides, thorium and uranium occur naturally in substantial, primordial, quantities. The radioactive decay of uranium produces transient amounts of actinium, protactinium and plutonium, and atoms of neptunium are occasionally produced from transmutation reactions in uranium ores. The other actinides are purely synthetic elements, although the first six actinides after plutonium would have been produced during the Oklo phenomenon (and long since decayed away),