igneous
Basalt
Extrusive Igneous Rock
AI-generated identification · may be incorrectHardness 6 on Mohs scale, dark gray to black color, dull luster, microcrystalline to aphanitic structure, specific gravity 2.8-3.0.
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Physical properties
Hardness 6 on Mohs scale, dark gray to black color, dull luster, microcrystalline to aphanitic structure, specific gravity 2.8-3.0.
Formation & geological history
Formed from the rapid cooling of low-viscosity basaltic lava exposed at or very near the Earth's surface.
Uses & applications
Used extensively in construction as crushed aggregate, railroad ballast, dimension stone, and in manufacturing rock wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the world's ocean basins and forming major volcanic features on other terrestrial planets like Mars and Venus.
Field identification & locations
Identify in the field by its dense, dark, fine-grained matrix, often showing vesicular textures from trapped gas bubbles. Commonly found in volcanic regions worldwide.
