igneous
Basalt
Mafic extrusive igneous rock
AI-generated identification · may be incorrectHardness 6 on Mohs scale, dark gray to black color, fine-grained aphanitic texture with possible phenocrysts, specific gravity 2.8-3.0.
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Physical properties
Hardness 6 on Mohs scale, dark gray to black color, fine-grained aphanitic texture with possible phenocrysts, specific gravity 2.8-3.0.
Formation & geological history
Formed by the rapid cooling of low-viscosity, magnesium- and iron-rich lava flows at the Earth's surface.
Uses & applications
Used extensively in construction as crushed aggregate, railroad ballast, and in the manufacturing of rock wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the world's ocean basins and forms massive geological formations like the Columbia River Flood Basalts.
Field identification & locations
Identify by its dark, dense, fine-grained groundmass often containing visible plagioclase or olivine crystals. Found globally in volcanic provinces.
