mineral
Copper-bearing quartz/rock fragment with attached mica
Chalcopyrite-bearing quartz or altered igneous rock; attached flake likely muscovite or biotite mica
AI-generated identification · may be incorrectMetallic brassy-gold and blue-green tarnish suggests chalcopyrite, with quartz or feldspar matrix and a strongly reflective mica flake. Chalcopyrite hardness is 3.5–4, metallic luster, imperfect cleavage, and specific gravity about 4.1–4.3; identification is uncertain from the image alone.
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Physical properties
Metallic brassy-gold and blue-green tarnish suggests chalcopyrite, with quartz or feldspar matrix and a strongly reflective mica flake. Chalcopyrite hardness is 3.5–4, metallic luster, imperfect cleavage, and specific gravity about 4.1–4.3; identification is uncertain from the image alone.
Formation & geological history
Likely formed in hydrothermal veins or altered igneous rocks, where copper sulfides crystallized from hot fluids; the specimen’s geological age cannot be determined visually. Surface oxidation produces blue-green copper sulfates and related tarnish minerals.
Uses & applications
Copper sulfide minerals are mined for copper; attractive pieces are collected, while mica has industrial uses in electrical insulation and fillers. This small natural specimen has modest decorative value.
Geological facts
Chalcopyrite is commonly called “peacock ore” when its iridescent tarnish is prominent, though artificially treated pieces are also sold under that name.
Field identification & locations
Look for brassy metallic grains, iridescent blue-purple oxidation, and a dark or pale matrix; a streak test, hardness test, and copper-mineral testing would help confirm it. Common localities include Peru, Mexico, Arizona, Montana, and Cornwall.
