igneous
Basalt
Extrusive igneous rock
AI-generated identification · may be incorrectHardness 6 on Mohs scale, dark gray to black color, fine-grained aphanitic texture, sub-conchoidal fracture, specific gravity 2.8-3.0.
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Physical properties
Hardness 6 on Mohs scale, dark gray to black color, fine-grained aphanitic texture, sub-conchoidal fracture, specific gravity 2.8-3.0.
Formation & geological history
Formed from the rapid cooling of low-viscosity basaltic lava flows exposed at or near the Earth's surface.
Uses & applications
Commonly used 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 crust underlying the oceans and forms most of the Hawaiian islands.
Field identification & locations
Identify in the field by its dark, dense, fine-grained matrix and frequent vesicular texture; found worldwide in volcanic provinces.
