igneous
Basalt
Mafic extrusive igneous rock
AI-generated identification · may be incorrectHardness of 6 on Mohs scale, dark gray to black color, fine-grained aphanitic texture, and subconchoidal fracture.
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Physical properties
Hardness of 6 on Mohs scale, dark gray to black color, fine-grained aphanitic texture, and subconchoidal fracture.
Formation & geological history
Formed from the rapid cooling of low-viscosity lava rich in magnesium and iron exposed at or very near the Earth's surface.
Uses & applications
Widely used in construction for road aggregates, railroad ballast, and dimension stone, as well as in manufacturing rock wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the world's ocean basins and forms massive geological features like the Giant's Causeway.
Field identification & locations
Identify by its dark color, heavy weight, and fine-grained matrix; commonly found in volcanic regions and oceanic crust worldwide.
