A reconnaissance search for uraniferous lignite and carbonaceous shale was made in western Montana and adjacent parts of Idaho during the summer of 1951. Particular emphasis in the examination was placed on coal and carbonaceous shale associated with volcanic rocks, as volcanic rocks in many areas appear to have released uranium to circulating ground water from which it was ,concentrated in carbonaceous material. Twenty-two areas in Montana and one area in Idaho were examined. The coal in five of these areas is of Cretaceous age. The coal and carbonaceous shale in the remaining 18 areas occur in Tertiary 'fake-bed' deposits of Oligocene and younger age. Both the Cretaceous and Tertiary coal and carbonaceous shale are associated with contemporaneous or younger volcanic rocks and pyrociastic sequences.
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Results of reconnaissance for uraniferous coal, lignite, and carbonaceous shale in western Montana