igneous
Small rounded pebble, likely basalt
Fine-grained mafic volcanic rock (likely basalt); image alone cannot confirm composition
AI-generated identification · may be incorrectGray-green, rounded, dull and fine-grained, with faint mottling; individual crystals are not visible. Basalt typically has Mohs hardness about 6 and consists mainly of plagioclase and pyroxene, often with olivine.
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Physical properties
Gray-green, rounded, dull and fine-grained, with faint mottling; individual crystals are not visible. Basalt typically has Mohs hardness about 6 and consists mainly of plagioclase and pyroxene, often with olivine.
Formation & geological history
Likely formed when mafic lava cooled at or near the surface, then became rounded by abrasion in water or sediment. Its age and exact origin cannot be determined from the photo.
Uses & applications
A pebble of this size is mainly suitable for collecting or decoration; basalt is also widely used as aggregate and paving stone.
Geological facts
Basalt is the most common volcanic rock in Earth's oceanic crust.
Field identification & locations
The small, rounded shape and dark, mottled appearance fit a water-worn volcanic pebble, but a fresh surface or mineral tests would be needed for reliable identification. Basalt is common worldwide, especially in volcanic regions and stream or beach gravels.
