igneous
Rounded fine-grained river stone, likely basaltic or andesitic rock
Probably basalt or andesite; exact identification requires testing
AI-generated identification · may be incorrectDull brown-gray, compact and fine-grained, with tiny pale mineral grains and rounded water-worn surfaces. Typical basalt/andesite hardness is about 6 on Mohs; individual crystals are too small to identify in the photo.
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Physical properties
Dull brown-gray, compact and fine-grained, with tiny pale mineral grains and rounded water-worn surfaces. Typical basalt/andesite hardness is about 6 on Mohs; individual crystals are too small to identify in the photo.
Formation & geological history
If volcanic, it formed when lava cooled at or near Earth’s surface; its rounded shape likely developed through prolonged transport and abrasion in water. No geological age can be determined from appearance alone.
Uses & applications
Commonly used as landscaping stone, aggregate, or a decorative specimen; this small ordinary pebble has little commercial value.
Geological facts
The pale specks may be feldspar or other mineral grains, but visual inspection alone cannot confirm composition.
Field identification & locations
Look for a dense, fine-grained texture and test hardness and streak; a hand lens or thin section can help distinguish basalt from andesite or other dark rocks. Rounded pebbles occur in riverbeds, beaches, and glacial deposits worldwide.
