igneous
Basalt
Extrusive Igneous Rock
AI-generated identification · may be incorrectHardness 6 on Mohs scale, dark gray to black color, dull luster, aphanitic to porphyritic crystal structure, 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 on Mohs scale, dark gray to black color, dull luster, aphanitic to porphyritic crystal structure, specific gravity 2.8-3.0.
Formation & geological history
Formed by the rapid cooling of low-viscosity lava rich in magnesium and iron exposed at or very near the surface of a planet or moon.
Uses & applications
Widely used in construction for crushed stone, railroad ballast, foundations, and manufacturing of rock wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's oceanic crust and also makes up extensive volcanic formations on the Moon and Mars.
Field identification & locations
Identify by its fine-grained, dark-colored matrix often found in columnar jointing formations or lava flows worldwide.
