mineral
Chalcopyrite
CuFeS2 (Copper Iron Sulfide)
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
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Physical properties
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.
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.
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