: a brown to black mineral that consists of massive uraninite, has a distinctive luster, contains radium, and is the chief ore-mineral source of uranium
Amorphous, dense, black, pitchy form of the crystalline uranium oxide mineral uraninite; it is one of the primary mineral ores of uranium. Pitchblende is found in granular masses and has a greasy lustre. Three chemical elements were first discovered in pitchblende: uranium, polonium, and radium. Deposits, frequently in association with uraninite or with secondary uranium minerals, are known in the Czech Republic, Britain, the Northwest Territories and Saskatchewan in Canada, and Arizona, Colorado, Montana, New Mexico, and Utah in the U.S.