igneous
Basalt
Mafic extrusive igneous rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, dark gray to black color, dull to sub-with luster, fine-grained aphanitic texture.
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Physical properties
Hardness of 6 on the Mohs scale, dark gray to black color, dull to sub-with luster, fine-grained aphanitic texture.
Formation & geological history
Formed from the rapid cooling of low-viscosity lava rich in iron and magnesium exposed at or very near the surface.
Uses & applications
Widely used in construction as crushed aggregate, railroad ballast, and in the manufacture of rock wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the world's ocean basins and forming vast continental flood basalts.
Field identification & locations
Identify by its heavy weight, dark color, and fine crystalline matrix often containing tiny plagioclase or olivine phenocrysts.
