igneous
Basalt
Mafic extrusive igneous rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, dark gray to black in color, dull luster, aphanitic crystal structure with microscopic grains, and specific gravity around 2.8 to 3.0.
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Physical properties
Hardness of 6 on the Mohs scale, dark gray to black in color, dull luster, aphanitic crystal structure with microscopic grains, and specific gravity around 2.8 to 3.0.
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 as crushed aggregate, railroad ballast, dimension stone, and in the manufacturing of rock wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's crustal portions underlying the ocean basins and also forms massive volcanic features like the Columbia River Flood Basalts.
Field identification & locations
Easily identified by its dark, fine-grained, heavy nature and vesicular or massive texture; found abundantly worldwide in volcanic regions.
