Uraninite in pitchblende from Great Bear Lake, Northwest Territories, embedded (for display) in a elipsis
Uranium dioxide (UO
2), a major
oxide mineral of
uranium. Uraninite is radioactive and usually forms black, gray, or brown crystals that are moderately hard and generally opaque. The elements uranium and radium were first extracted from uraninite ore from what is now the Czech Republic. It has also been mined in Germany and Canada, and in the Colorado Plateau (U.S.).
Seealso pitchblende.
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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
