igneous
Basalt
Extrusive Igneous Rock
Hardness of 6 on the Mohs scale, dark gray to black in color, dull to sub-withish luster, fine-grained aphanitic crystal structure, specific gravity around 2.8-3.0.
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Physical properties
Hardness of 6 on the Mohs scale, dark gray to black in color, dull to sub-withish luster, fine-grained aphanitic crystal structure, specific gravity around 2.8-3.0.
Formation & geological history
Formed from the rapid cooling of low-viscosity lava rich in magnesium and iron exposed at or very near the surface of a planet or moon.
Uses & applications
Used in construction, aggregate for roads, making rock wool insulation, and manufacturing tiles or countertops.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the world's ocean basins and also makes up extensive volcanic provinces like the Columbia River Basalts.
Field identification & locations
Identified by its dark color and very fine-grained texture; common worldwide in volcanic regions, oceanic crust, and flood basalt provinces.
