igneous
Basalt
Basalt (Extrusive Igneous Rock)
Hardness: 6 (Mohs scale), Color: Dark gray to black, Luster: Dull to sub-metallic, Crystal structure: Aphanitic (fine-grained), Cleavage: None, Specific gravity: 2.8-3.0
Identified More igneous →
Explore Basalt in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6 (Mohs scale), Color: Dark gray to black, Luster: Dull to sub-metallic, Crystal structure: Aphanitic (fine-grained), Cleavage: None, Specific gravity: 2.8-3.0
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava exposed at or very near the surface of a terrestrial planet or a moon. Most common rock in Earth's crust.
Uses & applications
Extensively used in construction for aggregate, road base, railroad ballast, and high-quality concrete. Also used for flooring, building stone, and statues.
Geological facts
Basalt is the most common rock type in the Earth's crust and makes up most of the ocean floor. It is also found on the Moon and Mars.
Field identification & locations
Identify by dark color, fine-grained texture, and high density. Commonly found in volcanic areas like the Pacific Northwest, Hawaii, and Iceland.
