mineral

Uraninite (Pitchblende)

Uranium dioxide (UO2)

Hardness: 5-6 (Mohs scale); Color: Black, brownish-black, or dark gray with yellow/green secondary oxidation; Luster: Submetallic, greasy, or dull; Crystal structure: Isometric (cubic); Cleavage: None/Conchoidal fracture; Specific gravity: 6.5-10.9 (very dense).

Hardness: 5-6 (Mohs scale)
Luster: Submetallic, greasy, or dull

Identified April 10, 2026More mineral →

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Physical properties

Formation & geological history

Primary mineral in hydrothermal ore veins, often associated with granite pegmatites. It is radioactive and forms over millions of years as uranium precipitates from hydrothermal fluids or crystallizes from magma.

Uses & applications

Primary ore of uranium; used in nuclear energy and historically for glass coloring. Highly valued by scientific collectors for its radioactive properties.

Geological facts

Uraninite is the most important ore of uranium. It was the material Marie Curie used to first isolate radium. Over time, it naturally decays into lead through various radioactive isotopes.

Field identification & locations

Identify in the field by its extreme weight (high density), dark color, and characteristic yellow 'uranium bloom' (secondary minerals like autunite). Collectors use Geiger counters to confirm its presence. Caution: radioactive source.