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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.
This entry comes from Encyclopædia Britannica Concise. For the full entry on pitchblende, visit Britannica.com.