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 glassy luster, fine-grained crystal structure, and a specific gravity of 2.8-3.0.
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Physical properties
Hardness of 6 on the Mohs scale, dark gray to black color, aphanitic to glassy luster, fine-grained crystal structure, and a specific gravity of 2.8-3.0.
Formation & geological history
Formed from the rapid cooling of low-viscosity, magnesium- and iron-rich lava flows exposed at or very near the Earth's surface.
Uses & applications
Widely used in construction for crushed stone in road bases, concrete aggregate, and dimension stone.
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
Identified by its dark, fine-grained matrix and often vesicular texture; found abundantly worldwide in volcanic regions.
