igneous
Basalt
Extrusive Igneous Rock
AI-generated identification · may be incorrectHardness of 6 on Mohs scale, dark gray to black color, dull luster, fine-grained aphanitic crystal structure, specific gravity around 2.8 to 3.0.
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Physical properties
Hardness of 6 on Mohs scale, dark gray to black color, dull luster, fine-grained aphanitic crystal structure, specific gravity around 2.8 to 3.0.
Formation & geological history
Formed from the rapid cooling of low-viscosity basaltic 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 manufacture of rock wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the world's oceans and also forms massive volcanic features like the Giant's Causeway.
Field identification & locations
Identify by its dark, dense, fine-grained appearance, often found in volcanic regions, oceanic crusts, and ancient lava flows worldwide.
