igneous
Native Copper in Basalt
Cu-element in Mafic Volcanic Rock (Basalt)
Hardness: 2.5-3 (copper), 6 (basalt); Color: Metallic reddish-orange copper in dark gray/greenish rock; Luster: Metallic to dull; Crystal structure: Cubic (copper), fine-grained amorphous (basalt); Specific gravity: 8.9 for copper.
- Hardness
- 2
- Color
- Metallic reddish-orange copper in dark gray/greenish rock
- Luster
- Metallic to dull
Identified More igneous →
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Physical properties
Hardness: 2.5-3 (copper), 6 (basalt); Color: Metallic reddish-orange copper in dark gray/greenish rock; Luster: Metallic to dull; Crystal structure: Cubic (copper), fine-grained amorphous (basalt); Specific gravity: 8.9 for copper.
Formation & geological history
Formed primarily in the Keweenawan Rift (approx. 1.1 billion years ago) through hydrothermal fluids filling gas bubbles (vesicles) and fractures within cooling basaltic lava flows.
Uses & applications
Major historical source of industrial copper; today it is primarily a collector's specimen and used for creating unique jewelry.
Geological facts
The Keweenaw Peninsula in Michigan is the only place on Earth where large-scale commercial mining of native copper occurred; one specimen found weighed over 400 tons.
Field identification & locations
Identified by high density compared to other rocks, metallic reddish streak, and the distinctive 'bloom' of copper within a dark matrix. Common in the Lake Superior region.
