igneous
Basalt
Extrusive Igneous Rock
AI-generated identification · may be incorrectHardness of 6 on Mohs scale; typically dark grey to black; fine-grained aphanitic texture with dull luster; specific gravity around 2.8-3.0.
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Physical properties
Hardness of 6 on Mohs scale; typically dark grey to black; fine-grained aphanitic texture with dull luster; specific gravity around 2.8-3.0.
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
Extensively 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 world's oceans and forming most planetary volcanic islands.
Field identification & locations
Identified by its dark color, heavy weight, and fine-grained texture; commonly found in oceanic crust and major continental flood basalt provinces.
