igneous
Basalt
Extrusive igneous rock
AI-generated identification · may be incorrectHardness 6 on Mohs scale, dark gray to black color, fine-grained aphanitic texture, dull luster, specific gravity around 2.9.
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Physical properties
Hardness 6 on Mohs scale, dark gray to black color, fine-grained aphanitic texture, dull luster, specific gravity around 2.9.
Formation & geological history
Formed from the rapid cooling of low-viscosity, iron- and magnesium-rich lava flows at the Earth's surface.
Uses & applications
Widely used in construction as crushed stone for road bases, concrete aggregate, and railroad ballast.
Geological facts
Basalt is the most common rock type in the Earth's oceanic crust and also forms major volcanic features on the Moon and Mars.
Field identification & locations
Identify in the field by its dark, dense, fine-grained matrix and frequent vesicular texture; common worldwide in volcanic regions.
