igneous
Basalt
Extrusive igneous rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, typically dark gray to black in color, with a-phanitic or a fine-grained crystal structure and dull luster.
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Physical properties
Hardness of 6 on the Mohs scale, typically dark gray to black in color, with a-phanitic or a fine-grained crystal structure and dull luster.
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
Commonly used in construction as crushed aggregate, in railroad ballast, and for making stone wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's crustal portions underlying the ocean basins and also forms significant volcanic formations on the Moon and Mars.
Field identification & locations
Easily identified by its dark, fine-grained appearance and heavy weight relative to its size; found worldwide in volcanic provinces.
