uraninit

Uraninit is not a recognized mineral name in contemporary mineral nomenclature. The term is most often a nonstandard spelling or variant of uraninite, the naturally occurring uranium oxide mineral. In scholarly and industrial sources, "uraninit" typically refers to the same material rather than to a distinct mineral species. The International Mineralogical Association lists uraninite as the primary uranium oxide mineral, with pitchblende as a historical name for material rich in impurities.

Uraninite is primarily uranium dioxide (UO2) with variable amounts of UO3, U3O8, and trace elements such as lead and thorium. The mineral commonly forms dense, black to black-brown masses and has a metallic to submetallic luster. It is radioactive and has a relatively high specific gravity (about 10–11 g/cm3).

It forms in hydrothermal veins and in granitic and metamorphic rocks associated with uranium-rich fluids; it also occurs in sedimentary deposits where uranium is concentrated. Uraninite is the principal ore from which uranium is extracted for nuclear fuel and other uses.

Crystallography is fluorite-like in the UO2 lattice; crystals are rare, with granular to massive habit. Because of radioactivity, handling and processing require appropriate safety measures and regulatory compliance.

See also: Uraninite, Pitchblende.