mineral
Copper-bearing rock, likely native copper in a weathered matrix
Native copper (Cu), tentatively with copper sulfide/oxide minerals
AI-generated identification · may be incorrectGreen-blue and brown metallic surface with irregular massive texture; likely Mohs hardness 2.5–3 for copper, metallic to earthy luster, no visible crystal faces, and high specific gravity (~8.9). The image alone cannot confirm mineral composition.
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Physical properties
Green-blue and brown metallic surface with irregular massive texture; likely Mohs hardness 2.5–3 for copper, metallic to earthy luster, no visible crystal faces, and high specific gravity (~8.9). The image alone cannot confirm mineral composition.
Formation & geological history
Probably formed in a hydrothermal copper deposit and later oxidized at the surface; age depends on its host deposit, commonly Precambrian to Mesozoic. Green coloration may reflect malachite or other copper-carbonate alteration.
Uses & applications
Primarily a collectible specimen; copper ores are mined for electrical wiring, plumbing, alloys, and industrial uses. This small rough piece has little commercial metal value.
Geological facts
Native copper is malleable and leaves a reddish metallic streak, while malachite is softer and bright green with a pale-green streak. Magnetism and visual inspection alone are unreliable for identification.
Field identification & locations
Common localities include Michigan’s Keweenaw Peninsula, Arizona, Cornwall, Chile, and Australia. Test carefully with streak, hardness, density, and ideally an XRF or mineralogical analysis; avoid acid testing without expertise.
