igneous
Rounded river pebble, likely fine-grained volcanic rock
Indeterminate from the image; possibly andesite or basalt
AI-generated identification · may be incorrectGray-brown, smooth and water-worn, with a dull to faintly silky luster and no visible crystals or cleavage. Hardness and specific gravity cannot be determined visually; if basaltic, typical hardness is about 5–6 Mohs.
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Physical properties
Gray-brown, smooth and water-worn, with a dull to faintly silky luster and no visible crystals or cleavage. Hardness and specific gravity cannot be determined visually; if basaltic, typical hardness is about 5–6 Mohs.
Formation & geological history
Likely a fragment of older volcanic rock rounded by transport in a stream or shoreline; its precise age and original formation cannot be established from appearance alone.
Uses & applications
Primarily a natural collectible or decorative pebble; similar rock is also used as aggregate and landscaping stone.
Geological facts
Its smooth, rounded shape reflects abrasion during transport, but color and surface texture alone are insufficient to identify the rock confidently.
Field identification & locations
A dense, fine-grained texture and lack of obvious layering or large crystals are consistent with volcanic rock. Exact identification requires examining a fresh surface and testing hardness; rounded pebbles occur in riverbeds, beaches, and glacial deposits worldwide.
