igneous
Basalt
Extrusive mafic igneous rock
AI-generated identification · may be incorrectHardness 6 on Mohs scale, dark gray to black color, dull to submetallic luster, microcrystalline or aphanitic texture, specific gravity around 2.9.
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Physical properties
Hardness 6 on Mohs scale, dark gray to black color, dull to submetallic luster, microcrystalline or aphanitic texture, specific gravity around 2.9.
Formation & geological history
Formed from the rapid cooling of low-viscosity basaltic lava exposed at or very near the Earth's surface.
Uses & applications
Widely used in construction as crushed stone for road bases, concrete aggregate, and in manufacturing 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 famous columnar jointing structures like the Giant's Causeway.
Field identification & locations
Identify by its dark, fine-grained matrix and heavy feel; commonly found in volcanic regions, oceanic crust, and continental flood basalt provinces worldwide.
