mineral
Likely chalcopyrite-bearing sulfide ore
Chalcopyrite (CuFeS₂), possibly with pyrite and secondary copper minerals
AI-generated identification · may be incorrectSmall irregular metallic specimen with brassy-gold, dark brown, and blue-green tarnish; likely Mohs 3.5–4, metallic luster, opaque, poor cleavage, and specific gravity about 4.1–4.3. The blue-green surface may be iridescent oxidation rather than the primary mineral color.
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Physical properties
Small irregular metallic specimen with brassy-gold, dark brown, and blue-green tarnish; likely Mohs 3.5–4, metallic luster, opaque, poor cleavage, and specific gravity about 4.1–4.3. The blue-green surface may be iridescent oxidation rather than the primary mineral color.
Formation & geological history
Forms in hydrothermal veins and copper sulfide deposits, commonly alongside pyrite, sphalerite, and quartz; most examples formed during ancient to geologically recent ore-deposit activity. Exact age and identity cannot be confirmed from the photograph alone.
Uses & applications
Chalcopyrite is an important copper ore and is occasionally collected for its colorful iridescent tarnish; attractive specimens may be sold as “peacock ore,” though many commercial examples are artificially treated.
Geological facts
Natural chalcopyrite commonly tarnishes purple, blue, green, and bronze. “Peacock ore” is often chalcopyrite or bornite, and may be acid-treated to intensify its colors.
Field identification & locations
Look for brassy metallic color, high density, softness relative to pyrite, and iridescent tarnish; a streak test, hardness test, or chemical analysis would improve identification. Common localities include Peru, Mexico, the United States, Canada, and Australia.
