igneous
Basalt
Mafic extrusive igneous rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, typically dark gray to black, aphanitic texture with fine-grained crystals, dull luster, and high specific gravity.
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Physical properties
Hardness of 6 on the Mohs scale, typically dark gray to black, aphanitic texture with fine-grained crystals, dull luster, and high specific gravity.
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 for crushed stone, road base, asphalt, and concrete aggregate, as well as in stonemasonry.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the world's ocean basins and forms famous formations like the Giant's Causeway.
Field identification & locations
Identified in the field by its dark color, heavy weight, and fine-grained texture; found extensively globally in volcanic regions and oceanic crusts.
