igneous
Basalt
Mafic extrusive igneous rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, dark gray to black color, dull luster, aphanitic crystal structure, no prominent cleavage, specific gravity around 2.9.
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Physical properties
Hardness of 6 on the Mohs scale, dark gray to black color, dull luster, aphanitic crystal structure, no prominent cleavage, specific gravity around 2.9.
Formation & geological history
Formed from the rapid cooling of low-viscosity, magnesium- and iron-rich lava flows at the Earth's surface.
Uses & applications
Widely used in construction for crushed stone, railroad ballast, and aggregate, as well as in stonemasonry.
Geological facts
Basalt is the most common rock type in the Earth's crustal portions underlying the ocean basins and forms famous formations like the Giant's Causeway.
Field identification & locations
Identify by its dark, fine-grained matrix and heavy feel; commonly found in volcanic regions worldwide.
