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, subconchoidal fracture, 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, subconchoidal fracture, specific gravity 2.8-3.0.
Formation & geological history
Formed by the rapid cooling of low-viscosity, iron- and magnesium-rich lava flows on the Earth's surface.
Uses & applications
Widely used in construction as crushed stone for road bases, concrete aggregate, and manufacturing of rock wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's oceanic crust and also forms extensive continental flood basalts.
Field identification & locations
Identify by its dark, fine-grained matrix often containing tiny visible phenocrysts; common in volcanic regions worldwide.
