mineral

Cuprite

Cuprite (Copper(I) oxide, Cu2O)

Hardness: 3.5-4 (Mohs); Color: Dark red to coppery-red, sometimes appearing near-black; Luster: Adamantine, sub-metallic, or earthy; Crystal structure: Isometric; Cleavage: Poor; Specific gravity: 6.1

Hardness: 3
Color: Dark red to coppery-red, sometimes appearing near-black
Luster: Adamantine, sub-metallic, or earthy

Identified March 27, 2026More mineral →

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Physical properties

Formation & geological history

Formed as a secondary mineral in the oxidized zone of copper ore deposits. It is created through the weathering of primary copper sulfides like chalcopyrite or chalcocite.

Uses & applications

Major ore of copper. High-quality transparent crystals (known as 'Ruby Copper') are occasionally faceted for collectors, though they are too soft for regular jewelry.

Geological facts

Also known as Ruby Copper due to its deep red internal reflections. It belongs to the oxide mineral group and is often found associated with native copper, malachite, and azurite.

Field identification & locations

Identify in the field by its high density (feels heavy for its size), red to brownish streak, and its association with green malachite stains. Commonly found in Arizona (USA), Namibia, and the Ural Mountains of Russia.