igneous
Basalt
Mafic extrusive igneous rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, typically dark gray to black in color, with a dull to sub-to-glassy luster and an aphanitic or fine-grained crystal structure.
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 of 6 on the Mohs scale, typically dark gray to black in color, with a dull to sub-to-glassy luster and an aphanitic or fine-grained crystal structure.
Formation & geological history
Formed from the rapid cooling of low-viscosity, magnesium- and iron-rich lava exposed at or very near the Earth's surface.
Uses & applications
Widely used in construction as crushed aggregate for roads, railroad ballast, and in the production of rock wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the ocean basins and forms extensive volcanic features like the Columbia River Basalts.
Field identification & locations
Identify in the field by its dark color, heavy weight, and fine-grained texture; commonly found in volcanic regions worldwide.
