radioactive, bright-yellow, soft and earthy vanadium mineral that is an important source of uranium. A hydrated potassium uranyl vanadate, K2(UO2)2(VO4)23H2O, pure carnotite contains about 53 percent uranium, 12 percent vanadium, and trace amounts of radium. It is of secondary origin, having been formed by alteration of primary uranium-vanadium minerals. It occurs chiefly with tyuyamunite (its calcium analogue) in sandstone, either disseminated or locally as small pure masses, particularly around fossil wood
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