igneous
Basalt
Basalt
Hardness 6 on Mohs scale, dark gray to black color, earthy to dull luster, fine-grained (aphanitic) texture, composition rich in pyroxene and plagioclase feldspar
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Physical properties
Hardness 6 on Mohs scale, dark gray to black color, earthy to dull luster, fine-grained (aphanitic) texture, composition rich in pyroxene and plagioclase feldspar
Formation & geological history
Extrusive igneous rock formed from the rapid cooling of low-viscosity basaltic lava exposed at or very near the Earth's surface
Uses & applications
Used in construction as crushed stone, aggregate in concrete and asphalt, dimensional stone, and mineral wool insulation
Geological facts
Basalt is the most common rock type in the Earth's crust, making up most of the oceanic crust as well as vast volcanic plateaus on land
Field identification & locations
Identified by its dark color, fine grain size, and heavy weight relative to volume. Found worldwide near active or extinct volcanic zones
