igneous
Basalt
Extrusive Igneous Rock
Hardness of 6 on the Mohs scale, dark gray to black in color, aphanitic (fine-grained) texture, dull to sub-woody luster, density around 2.9 g/cm3.
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Physical properties
Hardness of 6 on the Mohs scale, dark gray to black in color, aphanitic (fine-grained) texture, dull to sub-woody luster, density around 2.9 g/cm3.
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 in construction, crushed stone for road bases, railroad ballast, production of rock wool insulation, and manufacturing countertops.
Geological facts
Basalt is the most common rock type in the Earth's oceanic crust and is also found extensively on the Moon and Mars as dark volcanic plains (maria).
Field identification & locations
Identify by its dark, fine-grained matrix, sometimes containing small visible crystals of olivine or pyroxene. Commonly found in volcanic regions, oceanic islands, and continental flood basalt provinces worldwide.
