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 2.8-3.0.
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Physical properties
Hardness 6 on Mohs scale, dark gray to black color, fine-grained aphanitic texture, dull luster, specific gravity 2.8-3.0.
Formation & geological history
Formed from the rapid cooling of low-viscosity, magnesium- and iron-rich lava flows at the Earth's surface.
Uses & applications
Used extensively in construction as crushed stone for road bases, railroad ballast, and aggregate in concrete.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the world's ocean basins and forming most of oceanic islands.
Field identification & locations
Identify by its dark, fine-grained matrix and heavy feel. Found globally in volcanic provinces, rift zones, and oceanic crusts.
