igneous
Basalt
Extrusive igneous rock
AI-generated identification · may be incorrectHardness 6 on Mohs scale, dark gray to black color, dull luster, microcrystalline or aphanitic texture.
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Physical properties
Hardness 6 on Mohs scale, dark gray to black color, dull luster, microcrystalline or aphanitic texture.
Formation & geological history
Formed from the rapid cooling of low-viscosity basaltic lava exposed at or very near the Earth's surface.
Uses & applications
Used widely in construction as crushed stone for road bases, concrete aggregate, and in dimension stone.
Geological facts
Basalt is the most common rock type in the Earth's crustal portions underlying the world's ocean basins and forms much of the lunar maria.
Field identification & locations
Identify by its dark, fine-grained appearance, often containing small visible crystals like olivine or plagioclase in a dense matrix.
