igneous
Basalt
Extrusive Igneous Rock
AI-generated identification · may be incorrectHardness of 6 on Mohs scale, dark gray to black color, aphanitic texture with fine-grained crystals, dull luster.
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Physical properties
Hardness of 6 on Mohs scale, dark gray to black color, aphanitic texture with fine-grained crystals, dull luster.
Formation & geological history
Formed from the rapid cooling of low-viscosity lava rich in iron and magnesium exposed at or near the Earth's surface.
Uses & applications
Used extensively in construction as crushed stone for road bases, concrete aggregate, and dimension stone.
Geological facts
Basalt is the most common rock type in the Earth's crustal portions underlying the ocean basins and forms famous sites like the Giant's Causeway.
Field identification & locations
Identify in the field by its heavy, fine-grained dark appearance; commonly found in volcanic regions worldwide.
