igneous
Basalt
Mafic extrusive igneous rock
AI-generated identification · may be incorrectHardness 6 on Mohs scale, dark gray to black color, aphanitic texture, submetallic to dull luster, specific gravity around 2.9-3.0.
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Physical properties
Hardness 6 on Mohs scale, dark gray to black color, aphanitic texture, submetallic to dull luster, specific gravity around 2.9-3.0.
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 stone wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's crust, making up most of the ocean floor and large terrestrial volcanic provinces.
Field identification & locations
Identify in the field by its dark, fine-grained groundmass, often with visible tiny olivine or pyroxene phenocrysts. Common worldwide in volcanic regions.
