igneous
Basalt
Mafic extrusive igneous rock
AI-generated identification · may be incorrectHardness of 6 on Mohs scale, dark gray to black color, sub-aphanitic to aphanitic texture, dull luster, and high specific gravity.
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Physical properties
Hardness of 6 on Mohs scale, dark gray to black color, sub-aphanitic to aphanitic texture, dull luster, and high specific gravity.
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 widely in construction as crushed stone for road bases, railroad ballast, and in the 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
Easily identified in the field by its dark color, fine-grained texture, and weathering to a brownish crust; commonly found worldwide.
