mineral
Copper (native copper)
Native copper, Cu
AI-generated identification · may be incorrectSmall irregular metallic fragment with copper-brown color, bright metallic luster, and hackly/fractured surfaces. Mohs hardness 2.5–3; cubic crystal structure, usually massive or dendritic; specific gravity about 8.9. The image alone cannot exclude copper-rich slag or a copper-bearing alloy.
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Physical properties
Small irregular metallic fragment with copper-brown color, bright metallic luster, and hackly/fractured surfaces. Mohs hardness 2.5–3; cubic crystal structure, usually massive or dendritic; specific gravity about 8.9. The image alone cannot exclude copper-rich slag or a copper-bearing alloy.
Formation & geological history
Native copper forms when copper-rich hydrothermal fluids precipitate copper in fractures, commonly in basaltic volcanic rocks and oxidized sulfide deposits. Major deposits include Michigan, Arizona, Chile, and Australia; regional occurrence near 43.0°N, 108.4°W is possible but not especially diagnostic without host rock context.
Uses & applications
Used primarily as an important copper ore and historically for tools, ornaments, and electrical metal. Attractive natural specimens are collected, though most pieces are worth little unless unusually crystallized or large.
Geological facts
Fresh copper is salmon-red to orange and commonly develops a green patina (malachite/azurite) when weathered. It is malleable rather than brittle; a sharp edge or bend test on an inconspicuous area can help distinguish it from copper-colored rock.
Field identification & locations
Field tests: unusually high density, metallic copper streak, and conductivity support native copper; it should dent or deform rather than crumble. Estimated value: $5–$30 for a small common fragment; $50–$500+ for large, well-formed crystallized specimens.
