mineral

Chalcopyrite

CuFeS2 (Copper Iron Sulfide)

AI-generated identification · may be incorrect

Hardness: 3.5 to 4 on the Mohs scale. Color: Brass yellow, often with iridescent tarnish ranging from purple, blue, green, to red (peacock ore). Luster: Metallic. Crystal Structure: Tetragonal. Specific Gravity: 4.1 to 4.3.

Hardness: 3
Luster: Metallic

Identified August 2, 2026More mineral →

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Physical properties

Formation & geological history

Forms in hydrothermal veins, metamorphic rocks, and sedimentary deposits, often associated with other copper and iron sulfides. It precipitates from hot mineralizing solutions over geological time scales.

Uses & applications

Primary ore of copper, used extensively in electrical wiring, plumbing, and industry; also widely collected by mineral enthusiasts for its colorful tarnish.

Geological facts

Often called 'peacock copper' or 'peacock ore' due to its vibrant iridescent tarnish, though natural tarnish develops over time from oxidation, and some brightly colored specimens are treated with acid.

Field identification & locations

Identified by its brassy yellow color, metallic luster, greenish-black streak, and softer hardness than pyrite. Found globally in major copper-producing regions such as Chile, the USA, Mexico, and Peru.