Uraninite
Uraninite is a
uranium-rich
mineral with a composition that is largely UO
2, but which also contains UO
3 and
oxides of
lead,
thorium, and rare earths. The uraninite may occur as black octahedral
crystals of high
specific gravity (9.0 - 10.63); when in masses of pitch-like
lustre it is called
pitchblende. All uraninites and pitchblende contain a minute amount of
radium; it was in pitchblende from the Jáchymov in
Czechoslovakia that
Marie Curie discovered radium.
An important occurrence of pitchblende is at Great Bear Lake in the Northwest Territories of Canada, where it is found in large quantities associated with silver.
See also: list of minerals