igneous
Likely basalt
Basalt; chiefly plagioclase feldspar, pyroxene, and often olivine
AI-generated identification · may be incorrectDark gray-black, fine-grained to subtly crystalline, with dull to weakly glassy luster; Mohs hardness about 6, no obvious cleavage, and typical specific gravity 2.8–3.0. The image suggests a dense, irregular, possibly vesicle-poor specimen.
Identified More igneous →
Explore Likely basalt in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Dark gray-black, fine-grained to subtly crystalline, with dull to weakly glassy luster; Mohs hardness about 6, no obvious cleavage, and typical specific gravity 2.8–3.0. The image suggests a dense, irregular, possibly vesicle-poor specimen.
Formation & geological history
An extrusive mafic igneous rock formed when iron- and magnesium-rich lava rapidly cooled at or near Earth’s surface; specimens may range from recent volcanic material to Precambrian flows billions of years old.
Uses & applications
Widely used as crushed aggregate, road metal, railway ballast, riprap, and occasionally building stone; attractive polished pieces are used decoratively but have limited gemstone value.
Geological facts
Basalt is the most abundant volcanic rock on Earth and forms much of the oceanic crust, especially at mid-ocean ridges and hotspots.
Field identification & locations
Identify by its uniformly dark color, fine texture, high density, and lack of visible large crystals; common worldwide in volcanic regions, including Hawaii, Iceland, India, and the Pacific Northwest. A field test cannot exclude closely similar rocks such as diabase or andesite.
