igneous
Basalt
Extrusive Mafic Igneous Rock
AI-generated identification · may be incorrectHardness 6 on Mohs scale, dark gray to black color, dull luster, aphanitic crystal structure, specific gravity 2.8-3.0.
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Physical properties
Hardness 6 on Mohs scale, dark gray to black color, dull luster, aphanitic crystal structure, specific gravity 2.8-3.0.
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 widely in construction as crushed stone for road bases, railroad ballast, and in the production of rock wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's oceanic crust and forms famous geological features like the Giant's Causeway.
Field identification & locations
Identify by its dark, fine-grained matrix and vesicular texture; found abundantly in volcanic regions worldwide.
