igneous
Basalt
Extrusive Igneous Rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, typically dark gray to black in color, with an aphanitic or fine-grained texture and vitreous to dull luster.
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Physical properties
Hardness of 6 on the Mohs scale, typically dark gray to black in color, with an aphanitic or fine-grained texture and vitreous to dull luster.
Formation & geological history
Formed from the rapid cooling of low-viscosity, iron- and magnesium-rich lava exposed at or very near the Earth's surface.
Uses & applications
Widely used in construction for crushed stone, aggregate in concrete, railroad ballast, and in the manufacturing of rock wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's oceanic crust and is also found abundantly on the lunar maria and the surface of Mars.
Field identification & locations
Identified in the field by its dark color, fine-grained matrix, and frequent vesicular texture caused by trapped gas bubbles.
