igneous
Basalt
Extrusive igneous rock
AI-generated identification · may be incorrectHardness 6 on Mohs scale, dark gray to black color, dull luster, microcrystalline or aphanitic structure, specific gravity around 2.9.
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Physical properties
Hardness 6 on Mohs scale, dark gray to black color, dull luster, microcrystalline or aphanitic structure, specific gravity around 2.9.
Formation & geological history
Formed from the rapid cooling of low-viscosity basaltic lava exposed at or very near the Earth's surface.
Uses & applications
Used extensively in construction as crushed aggregate, railroad ballast, and dimension stone.
Geological facts
Basalt is the most common rock type in the Earth's crustal portions underlying the ocean basins.
Field identification & locations
Identify by its dense, dark, fine-grained matrix; commonly found in volcanic regions and oceanic crusts worldwide.
