igneous
Basalt
Extrusive Igneous Rock
AI-generated identification · may be incorrectHardness 6 on Mohs scale, dark gray to black color, fine-grained aphanitic texture, dull luster, specific gravity 2.8-3.0.
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Physical properties
Hardness 6 on Mohs scale, dark gray to black color, fine-grained aphanitic texture, dull luster, specific gravity 2.8-3.0.
Formation & geological history
Formed from the rapid cooling of low-viscosity lava rich in iron and magnesium exposed at or very near the Earth's surface.
Uses & applications
Used extensively in construction, as crushed stone for road bases, railroad ballast, and in the production of rock wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's oceanic crust and also makes up extensive volcanic formations on the Moon and Mars.
Field identification & locations
Identify by its dark, fine-grained groundmass, often with microscopic crystals visible only under magnification; found worldwide in volcanic provinces.
