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 fine-grained, aphanitic texture and dull to submetallic luster.
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Physical properties
Hardness of 6 on the Mohs scale, typically dark gray to black in color with a fine-grained, aphanitic texture and dull to submetallic luster.
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 for roads, railroad ballast, and in the production of stone wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the world's ocean basins and forms massive geological features like the Columbia River Flood Basalts.
Field identification & locations
Easily identified in the field by its dark color, heavy weight relative to size, and occasional vesicular texture from trapped gas bubbles.
