igneous
Dark mafic rock fragment, possibly basalt
Basalt (tentative; image alone is insufficient for a definitive identification)
AI-generated identification · may be incorrectDark gray to black, rough and fine-grained, with scattered lighter flecks; typical basalt is mainly plagioclase and pyroxene, Mohs hardness about 6, and specific gravity around 2.8–3.0. Crystal structure is mostly too fine to see; no obvious cleavage is visible.
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Physical properties
Dark gray to black, rough and fine-grained, with scattered lighter flecks; typical basalt is mainly plagioclase and pyroxene, Mohs hardness about 6, and specific gravity around 2.8–3.0. Crystal structure is mostly too fine to see; no obvious cleavage is visible.
Formation & geological history
Basalt forms when iron- and magnesium-rich lava cools at or near the surface; it occurs from recent eruptions to rocks billions of years old. The image does not establish the specimen’s age or setting.
Uses & applications
Basalt is widely used as crushed aggregate, road stone, and building stone; this small fragment has little commercial value unless its provenance or features are notable.
Geological facts
Basalt is among Earth’s most abundant volcanic rocks and also forms much of the ocean floor.
Field identification & locations
A fresh surface is typically dark and dense, with tiny crystals; distinguish it from slag or other dark rocks by examining texture and context. Common worldwide, especially in volcanic regions.
