igneous
Rounded gray river pebble, likely basaltic rock
Fine-grained basalt or andesite; exact identification requires testing
AI-generated identification · may be incorrectDark gray-brown, dull to subtly granular, with tiny pale mineral flecks and no visible layering or cleavage. Likely hardness about 5–6 Mohs and specific gravity roughly 2.7–3.1; rounded by abrasion and weathering.
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Physical properties
Dark gray-brown, dull to subtly granular, with tiny pale mineral flecks and no visible layering or cleavage. Likely hardness about 5–6 Mohs and specific gravity roughly 2.7–3.1; rounded by abrasion and weathering.
Formation & geological history
Probably an erosion-rounded volcanic pebble transported in a stream or beach environment. Basalt/andesite formed from rapidly cooled lava, generally from relatively young to ancient volcanic settings; its geological age cannot be determined visually.
Uses & applications
Commonly used as landscaping stone, aggregate, ballast, and decorative pebble; this ordinary specimen has little jewelry or commercial value.
Geological facts
Its smooth, flattened shape reflects prolonged water or sediment abrasion rather than crystal growth. The pale specks may be plagioclase, weathered feldspar, or quartz, but a hand lens and tests are needed for confirmation.
Field identification & locations
Look for a fine-grained, dense, dark volcanic texture; basalt is commonly weakly magnetic, while andesite may be less magnetic. Common in volcanic terrains, river gravels, and beaches; estimated value is $1–$5 as an ordinary specimen, or up to $10–$20 if locally significant or attractively polished.
