igneous
Basalt
Extrusive Igneous Rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, dark gray to black in color, dull to sub-woody luster, fine-grained aphanitic crystal structure, and a specific gravity of 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 to sub-woody luster, fine-grained aphanitic crystal structure, and a specific gravity of 2.8 to 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 surface of a planet or moon.
Uses & applications
Extensively used in construction as crushed aggregate for road bases, concrete production, and railroad ballast, as well as in stonemasonry.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the world's ocean basins and forms famous formations like the Giant's Causeway.
Field identification & locations
Identified in the field by its dark, fine-grained appearance and heavy weight. Found worldwide in volcanic provinces, oceanic crust, and flood basalt traps.
