igneous
Dark rounded pebble
Likely basalt or fine-grained mafic volcanic rock
AI-generated identification · may be incorrectDark gray-green, dull to faintly vitreous luster, fine-grained and rounded by abrasion; typical basalt hardness is about 6 Mohs, with no visible cleavage and specific gravity around 2.8–3.0.
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Physical properties
Dark gray-green, dull to faintly vitreous luster, fine-grained and rounded by abrasion; typical basalt hardness is about 6 Mohs, with no visible cleavage and specific gravity around 2.8–3.0.
Formation & geological history
Likely weathered and water-worn basalt formed from rapidly cooled lava, generally of Cenozoic or older age; exact age and source cannot be determined from the image.
Uses & applications
Common basalt is used as aggregate, paving stone, riprap, and landscaping material; small ordinary pebbles have negligible commercial value.
Geological facts
The specimen appears dense, opaque, and relatively uniform, consistent with a volcanic pebble rather than a crystal-rich granite or a metallic meteorite.
Field identification & locations
Identify by its dark color, fine texture, heft, and lack of obvious layering or large crystals; common worldwide in volcanic terrains, riverbeds, beaches, and glacial deposits. A streak, magnetism test, and fresh broken surface would improve identification.
