igneous
Basalt
Extrusive Igneous Rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, dark gray to black color, fine-grained aphanitic texture, dull luster, high specific gravity.
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Physical properties
Hardness of 6 on the Mohs scale, dark gray to black color, fine-grained aphanitic texture, dull luster, high specific gravity.
Formation & geological history
Formed from the rapid cooling of low-viscosity basaltic lava exposed at or very near the Earth's surface.
Uses & applications
Commonly used in construction as crushed stone for road bases, concrete aggregate, and in railroad ballast.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the world's ocean basins and forms much of the Moon's maria.
Field identification & locations
Identify in the field by its dark color, fine-grained texture, and dense, heavy feel. Widely distributed globally in volcanic regions.
