igneous
Dark rounded stone, likely basalt or weathered mafic rock
Basalt (probable; identification uncertain from photograph)
AI-generated identification · may be incorrectFine-grained, dark gray-green, dull to weakly glassy, with no visible crystals or cleavage; estimated Mohs hardness 5–6 and specific gravity about 2.8–3.1.
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Physical properties
Fine-grained, dark gray-green, dull to weakly glassy, with no visible crystals or cleavage; estimated Mohs hardness 5–6 and specific gravity about 2.8–3.1.
Formation & geological history
Basalt forms when iron- and magnesium-rich lava cools rapidly at or near Earth’s surface, commonly in volcanic fields and oceanic crust; its age cannot be determined from the image.
Uses & applications
Used as crushed aggregate, road base, building stone, and landscaping material; attractive polished pieces may be collected but usually have low value.
Geological facts
The rounded shape and weathered surface suggest transport by water or abrasion rather than a naturally crystal-faced specimen.
Field identification & locations
Look for a uniformly fine texture, dark color, relatively high density, and possible tiny vesicles or feldspar specks; common worldwide, especially near volcanic terrains and stream gravels.
