igneous
Rounded gray-green rock (likely andesite or basalt cobble)
Undetermined fine-grained volcanic rock; composition cannot be confirmed from the image
AI-generated identification · may be incorrectGray-green, mottled, rounded surface with a dull to slightly granular luster; crystals are too fine to resolve. Hardness and specific gravity cannot be measured visually; no obvious cleavage is visible.
Identified More igneous →
Explore Rounded gray-green rock (likely andesite or basalt cobble) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Gray-green, mottled, rounded surface with a dull to slightly granular luster; crystals are too fine to resolve. Hardness and specific gravity cannot be measured visually; no obvious cleavage is visible.
Formation & geological history
Its rounded shape suggests water-worn transport from an igneous source, but the image does not establish its exact formation process or age. Volcanic rocks such as andesite and basalt form when lava cools at or near the surface.
Uses & applications
Likely a natural hand specimen or collectible; volcanic stone is also used as aggregate and building stone.
Geological facts
The specimen’s smooth, rounded form is consistent with abrasion during transport, though it could also have been shaped or polished.
Field identification & locations
A photo alone cannot reliably distinguish basalt, andesite, or other gray-green rocks. Field identification requires checking grain size, hardness, streak, and fresh surfaces; similar volcanic rocks occur worldwide.
