igneous
Basalt
Mafic extrusive igneous rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, dark gray to black color, aphanitic to porphyritic texture, and dull luster.
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Physical properties
Hardness of 6 on the Mohs scale, dark gray to black color, aphanitic to porphyritic texture, and dull luster.
Formation & geological history
Formed from 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 stone for road bases, concrete aggregate, and in the production of rock wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the world's oceans and forms extensive volcanic plateaus.
Field identification & locations
Identify in the field by its dark, fine-grained groundmass often containing visible phenocrysts of olivine or plagioclase, found worldwide in volcanic regions.
