igneous
Basalt
Mafic extrusive igneous rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, dark gray to black color, aphanitic to porphyritic texture, and dull luster.
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Physical properties
Hardness of 6 on the Mohs scale, dark gray to black color, aphanitic to porphyritic texture, and dull luster.
Formation & geological history
Formed from the rapid cooling of low-viscosity, magnesium- and iron-rich lava exposed at or very near the Earth's surface.
Uses & applications
Widely used in construction as crushed stone for road bases, concrete aggregate, and in manufacturing stone wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the oceans and forms famous columns like the Giant's Causeway.
Field identification & locations
Identify by its dark, fine-grained groundmass and heavy weight; found globally in volcanic regions and oceanic crusts.
