igneous
Basalt
Extrusive Igneous Rock
AI-generated identification · may be incorrectHardness 6 on Mohs scale; dark gray to black color; fine-grained aphanitic luster; amorphous to microcrystalline structure; 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 luster; amorphous to microcrystalline structure; specific gravity 2.8-3.0.
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
Used extensively in construction as crushed stone for road bases, concrete aggregate, and manufacturing of stone wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the world's ocean basins and forms massive geological formations like the Columbia River Flood Basalts.
Field identification & locations
Identify by its dark, dense, fine-grained appearance, often containing tiny visible crystals of plagioclase or olivine. Common globally in volcanic regions and oceanic crust.
