igneous
Dark, water-worn stone (possibly basalt)
Basalt; identification is uncertain from the image alone
AI-generated identification · may be incorrectDark gray to black, fine-grained, dull to slightly glossy, and rounded by abrasion. Basalt typically has Mohs hardness 5–6 and a dense, interlocking crystalline texture; crystal structure and composition cannot be confirmed visually here.
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Physical properties
Dark gray to black, fine-grained, dull to slightly glossy, and rounded by abrasion. Basalt typically has Mohs hardness 5–6 and a dense, interlocking crystalline texture; crystal structure and composition cannot be confirmed visually here.
Formation & geological history
Basalt forms when iron- and magnesium-rich lava cools at or near the surface; it occurs in volcanic regions of many ages. The specimen’s rounded shape suggests transport and wear by water or other abrasion.
Uses & applications
Basalt is widely used as crushed aggregate, road stone, and building material; this small piece is mainly suitable for collecting or display.
Geological facts
Basalt commonly contains plagioclase feldspar and pyroxene, sometimes with olivine. A single dark, rounded specimen cannot be reliably distinguished from other dark rocks by appearance alone.
Field identification & locations
Look for a fine-grained, dense texture and occasional tiny crystals; a streak, hardness, and fresh broken surface can help confirm identification. Basalt is common in volcanic terrains and river gravels.
