mineral
Peacock ore (likely chalcopyrite-bornite specimens)
Iridescent chalcopyrite, CuFeS₂, commonly altered to bornite, Cu₅FeS₄
AI-generated identification · may be incorrectBrassy metallic luster with artificial-looking purple, blue, green, and gold tarnish; opaque, massive, and irregularly fractured. Mohs hardness 3.5–4 for chalcopyrite and 3–3.25 for bornite; specific gravity about 4.1–5.1; no prominent cleavage.
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Physical properties
Brassy metallic luster with artificial-looking purple, blue, green, and gold tarnish; opaque, massive, and irregularly fractured. Mohs hardness 3.5–4 for chalcopyrite and 3–3.25 for bornite; specific gravity about 4.1–5.1; no prominent cleavage.
Formation & geological history
A copper-iron sulfide formed in hydrothermal veins and magmatic-hydrothermal ore deposits, generally during Precambrian to Phanerozoic geologic events. The vivid colors are a thin oxidation/tarnish film, often enhanced by heating or acid treatment.
Uses & applications
Primarily a low-cost mineral specimen and lapidary collectible; its copper content is economically important in untreated ore, but these small pieces have negligible industrial value.
Geological facts
“Peacock ore” is a trade name rather than a single mineral, and many brightly colored specimens sold under it are treated chalcopyrite. Natural bornite commonly tarnishes from bronze to purple-blue.
Field identification & locations
Identify by metallic brassy color, heavy feel, softness, and multicolored tarnish; it is commonly found in copper deposits in Mexico, Peru, the United States, and Canada. Avoid assuming color alone proves natural bornite or untreated material.
