Pitchblende

Pitchblende, radioactive mineral composed of the mineral uraninite, UO₂; it is one of the main mineral ores of uranium. It is historically important as the mineral in which the chemical elements polonium and radium were first discovered in 1898 by the French scientists Pierre and Marie Curie. Pitchblende was commercially important only as a source of radium until World War II, when it became extremely important as a source of uranium needed for the production of the atomic bomb.

Pitchblende is a black, opaque mineral with a dull, pitchlike luster. The hardness is 5.5, and the specific gravity, which is extremely high for a mineral, ranges from 9.0 to 9.7. It crystallizes in the isometric system (see Crystal) and usually occurs in massive formations as a constituent of granite rocks and pegmatites or as a secondary mineral associated with silver, lead, or copper ores. Although the ores do not occur in large quantities throughout the world, the major sources of pitchblende are located in South Africa, the Czech Republic, Canada, Germany, and France. In the U.S. the most important source is a deposit found in Marysvale, Utah. Smaller deposits have been discovered in Connecticut, North Carolina, and Colorado.