mineral
Chalcopyrite
Copper iron sulfide (CuFeS2)
Hardness of 3.5 to 4 on the Mohs scale, brass-yellow to golden-yellow color often with an iridescent tarnish, metallic luster, tetragonal crystal system, indistinct cleavage, and a specific gravity of 4.1 to 4.3.
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Physical properties
Hardness of 3.5 to 4 on the Mohs scale, brass-yellow to golden-yellow color often with an iridescent tarnish, metallic luster, tetragonal crystal system, indistinct cleavage, and a specific gravity of 4.1 to 4.3.
Formation & geological history
Forms in hydrothermal vein deposits, pegmatites, and sedimentary rock sequences through low- to high-temperature mineral-rich fluids, often associated with other sulfide minerals.
Uses & applications
Primary ore of copper, used in electrical wiring, plumbing, and occasionally cut as a collector's mineral specimen.
Geological facts
Chalcopyrite is commonly known as 'fool's gold' due to its brassy metallic look, though it is softer and darker than pyrite and can easily be distinguished by its greenish-black streak and tendency to tarnish into iridescent purples and blues.
Field identification & locations
Identified by its distinctive brassy yellow color, metallic luster, softness compared to pyrite, and common iridescent peacock-color tarnish. Found worldwide in major copper-mining regions such as Chile, the United States, and Mexico.
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