igneous
Basalt
Extrusive Igneous Rock
AI-generated identification · may be incorrectHardness 6 on Mohs scale, dark gray to black color, dull to sub-to-sub-metallic luster, aphanitic texture with microscopic crystals, and a specific gravity around 2.9.
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 to sub-to-sub-metallic luster, aphanitic texture with microscopic crystals, and a specific gravity around 2.9.
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 manufacturing of rock wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's crustal portions underlying the ocean basins and also forms extensive continental flood basalts.
Field identification & locations
Identify by its dark, fine-grained matrix and vesicular cavities; commonly found in volcanic regions worldwide, including East African rift zones.
