igneous
Basalt
Mafic extrusive igneous rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, typically dark gray to black in color, with a-phanitic or glassy luster and fine-grained crystal structure.
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Physical properties
Hardness of 6 on the Mohs scale, typically dark gray to black in color, with a-phanitic or glassy luster and fine-grained crystal structure.
Formation & geological history
Formed from the rapid cooling of low-viscosity, magnesium- and iron-rich lava flows on the Earth's surface.
Uses & applications
Used widely in construction aggregates, road base, asphalt, and railroad ballast.
Geological facts
Basalt is the most common rock type in the Earth's oceanic crust and also makes up extensive volcanic provinces on continents.
Field identification & locations
Identify by its dark, dense, fine-grained appearance; commonly found globally in volcanic regions and ocean basins.
