igneous
Basalt
Mafic extrusive igneous rock
AI-generated identification · may be incorrectHardness 6 on Mohs scale, dark gray to black color, dull luster, aphanitic fine-grained crystal structure, specific gravity around 2.8-3.0.
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Physical properties
Hardness 6 on Mohs scale, dark gray to black color, dull luster, aphanitic fine-grained crystal structure, specific gravity around 2.8-3.0.
Formation & geological history
Formed from the rapid cooling of low-viscosity basaltic lava flows exposed at or very near the Earth's surface.
Uses & applications
Widely used in construction for road aggregate, railroad ballast, building stone, and in manufacturing mineral wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the world's oceans and forms extensive volcanic features like the Columbia River Plateaus.
Field identification & locations
Identify by its dark, fine-grained groundmass, often vesicular with small gas cavities, commonly found globally in volcanic regions and oceanic crusts.
