igneous
Dark-colored rock fragment, possibly basalt
Basalt (tentative; image alone is insufficient for reliable identification)
AI-generated identification · may be incorrectDark gray to black, fine-grained appearance with a pale, rough weathered or mineral-coated area. Basalt typically contains plagioclase and pyroxene, sometimes olivine; hardness is about 5–6 Mohs, with no obvious cleavage and a specific gravity near 2.8–3.0.
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Physical properties
Dark gray to black, fine-grained appearance with a pale, rough weathered or mineral-coated area. Basalt typically contains plagioclase and pyroxene, sometimes olivine; hardness is about 5–6 Mohs, with no obvious cleavage and a specific gravity near 2.8–3.0.
Formation & geological history
If basalt, it formed when iron- and magnesium-rich lava cooled at or near the surface, commonly in volcanic settings. Basalt occurs from ancient to geologically recent eruptions; the specimen’s age cannot be determined from the image.
Uses & applications
Basalt is widely used as crushed aggregate, road stone, and construction material; attractive specimens may be collected or cut for decorative use.
Geological facts
The pale material may be weathering or a secondary mineral, but its identity is not visible clearly enough to determine.
Field identification & locations
A dense, fine-grained dark interior with tiny crystals supports basalt identification; check fresh surfaces and hardness. Basalt is common in volcanic regions worldwide.
