igneous
Fine-grained volcanic rock, likely basalt
Basalt (tentative; exact identification requires closer examination)
AI-generated identification · may be incorrectDark gray-brown, dull and fine-grained, with small dark specks and irregular fractures; likely composed mainly of plagioclase and pyroxene, perhaps olivine. Typical basalt hardness is about 6 on Mohs; individual crystals are too small to identify here.
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Physical properties
Dark gray-brown, dull and fine-grained, with small dark specks and irregular fractures; likely composed mainly of plagioclase and pyroxene, perhaps olivine. Typical basalt hardness is about 6 on Mohs; individual crystals are too small to identify here.
Formation & geological history
Basalt forms when iron- and magnesium-rich lava cools rapidly at or near the surface; it occurs across a wide range of geological ages. The image alone cannot establish this specimen’s age or source.
Uses & applications
Basalt is widely used as crushed aggregate, road stone, and building stone; this small rough specimen has little practical or gem use.
Geological facts
Basalt is among Earth’s most common volcanic rocks and forms much of the ocean floor.
Field identification & locations
A dense, fine-grained texture and lack of visible large crystals support basalt, but the specimen could be another fine-grained rock; location and a fresh surface would help confirm it. Common worldwide in volcanic regions and ancient lava flows.
