igneous
Dark, fine-grained rock pebble
Possibly basalt (composition cannot be confirmed from the image)
AI-generated identification · may be incorrectSmall, rounded, dark gray-green pebble with a dull to slightly sparkly surface. If basalt, it is typically Mohs 5–6, fine-grained, and composed mainly of plagioclase and pyroxene; crystal structure and specific gravity cannot be determined visually here.
Identified More igneous →
Explore Dark, fine-grained rock pebble in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Small, rounded, dark gray-green pebble with a dull to slightly sparkly surface. If basalt, it is typically Mohs 5–6, fine-grained, and composed mainly of plagioclase and pyroxene; crystal structure and specific gravity cannot be determined visually here.
Formation & geological history
A pebble may have been rounded by water or abrasion from a larger rock. Basalt forms when mafic lava cools at or near the surface, most often in geologically recent volcanic settings.
Uses & applications
A specimen of this size is mainly suitable for collecting or display; basalt is also used as aggregate, paving stone, and construction material.
Geological facts
Fine-grained basalt crystals are usually too small to distinguish without magnification.
Field identification & locations
Look for a uniformly dark, dense pebble, sometimes with tiny pale feldspar grains; confirmatory tests or closer examination are needed to identify it reliably. Basalt is common in volcanic regions and river or beach gravels.
