igneous
Basalt
Extrusive Igneous Rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, dark gray to black color, dull to sub-to-submetallic luster, and a-aphanitic (fine-grained) crystal structure.
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Physical properties
Hardness of 6 on the Mohs scale, dark gray to black color, dull to sub-to-submetallic luster, and a-aphanitic (fine-grained) crystal structure.
Formation & geological history
Formed from the rapid cooling of low-viscosity lava rich in iron and magnesium exposed at or very near the surface of a planet or moon.
Uses & applications
Widely used in construction for crushed stone in road bases, concrete aggregate, and in the production of rock wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's crustal portions underlying the world's oceans and forms majestic columnar jointing like at the Giant's Causeway.
Field identification & locations
Identified in the field by its dark color, heavy weight, and fine-grained texture; found extensively in volcanic regions and oceanic crusts worldwide.
