igneous
Water-worn brown pebble, likely basalt or other fine-grained volcanic rock
Undetermined mafic volcanic rock; basalt is a plausible identification
AI-generated identification · may be incorrectSmooth, rounded surface; brown weathering rind with darker mottling and a subtle sheen. If basalt, it is typically fine-grained, Mohs 5–6, composed mainly of plagioclase and pyroxene; the photo does not show crystals clearly enough for a firm identification.
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Physical properties
Smooth, rounded surface; brown weathering rind with darker mottling and a subtle sheen. If basalt, it is typically fine-grained, Mohs 5–6, composed mainly of plagioclase and pyroxene; the photo does not show crystals clearly enough for a firm identification.
Formation & geological history
Likely formed when lava cooled at or near Earth’s surface, then was rounded by water abrasion; its age and original source cannot be determined from the image.
Uses & applications
This small pebble is mainly suitable for collecting or decoration; basalt is also widely used as aggregate, paving stone, and construction material.
Geological facts
Iron-bearing minerals can oxidize and give volcanic rocks brown weathering colors; a wet or polished surface can appear glossy.
Field identification & locations
Its rounded shape indicates transport by water, but identifying basalt versus other pebble rocks requires examining a fresh broken surface, grain size, and hardness.
