igneous
Basalt
Extrusive igneous rock
Hardness of 6 on the Mohs scale, typically dark gray to black in color, aphanitic (fine-grained) texture, dull to submetallic luster, composed mainly of plagioclase feldspar and pyroxene.
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Physical properties
Hardness of 6 on the Mohs scale, typically dark gray to black in color, aphanitic (fine-grained) texture, dull to submetallic luster, composed mainly of plagioclase feldspar and pyroxene.
Formation & geological history
Formed from the rapid cooling of low-viscosity lava rich in magnesium and iron exposed at or very near the surface of a planet or moon.
Uses & applications
Used extensively in construction as crushed aggregate, for railroad ballast, road bases, and in the production of stone wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the world's oceans, and it is also abundantly found on the Moon and Mars.
Field identification & locations
Easily identified by its dark, fine-grained appearance, heavy weight, and dense, compact nature; commonly found in volcanic regions and oceanic crusts worldwide.
