What is Uraninite?
Uraninite is the principal uranium oxide mineral, usually black and heavy, and an important source of uranium in hydrothermal, pegmatitic and sedimentary ore systems.
Mineralogy and structure
Reference formula: UO2. Uraninite has a fluorite-type cubic structure, but natural material commonly contains lead, thorium, rare earth elements and alteration products. It is radioactive; the exact COD 9009049 model is shown as a scientific reference, not a handling recommendation. Uraninite is classified with oxides and has cubic crystal symmetry. Typical hardness is 5–6 on the Mohs scale and specific gravity is approximately 8.5–10.9.
Colour, lustre and habit
Typical colours include black, brown-black, grey, greenish-black. The usual cubic, massive, granular habit and sub-metallic, vitreous, greasy lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Uraninite forms in or is associated with granite pegmatites, hydrothermal veins, unconformity-related deposits, sandstones and metamorphic rocks. Important documented localities include Canada, the United States, the Czech Republic, Australia, Namibia, South Africa and Kazakhstan.
A heavy black record of uranium geology
Uraninite is collected for its scientific importance rather than casual display alone. A documented mine, measured radiation profile and secure presentation are more valuable than a glossy surface.
Collecting and care
Radioactive and potentially chemically hazardous: keep specimens sealed or shielded as appropriate, avoid dust, do not cut or grind, limit exposure and follow local radiation-safety guidance.
