igneous
Dark gray-green, fine-grained rock (likely basalt)
Basalt; exact identification requires closer examination
AI-generated identification · may be incorrectAppears dark gray-green, dull, and fine-grained, with a rough, fractured surface. Basalt is mainly plagioclase and pyroxene, sometimes olivine; hardness is about 6 on the Mohs scale, and its crystals are typically too small to see unaided.
Identified More igneous →
Explore Dark gray-green, fine-grained rock (likely basalt) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Appears dark gray-green, dull, and fine-grained, with a rough, fractured surface. Basalt is mainly plagioclase and pyroxene, sometimes olivine; hardness is about 6 on the Mohs scale, and its crystals are typically too small to see unaided.
Formation & geological history
Basalt forms when low-silica lava cools rapidly at or near Earth’s surface; it occurs from ancient geological periods to recent eruptions. The image alone cannot establish the specimen’s age or confirm its composition.
Uses & applications
Basalt is widely used as crushed aggregate, road stone, and building stone; this unpolished piece has little typical jewelry use.
Geological facts
Basalt makes up much of Earth’s oceanic crust and occurs in extensive lava fields and volcanic islands.
Field identification & locations
A dark, dense-looking rock with a fine-grained texture is consistent with basalt; check for tiny crystals or gas holes, and use a fresh surface for identification. Basalt is common worldwide, especially in volcanic regions.
