igneous
Basalt
Mafic extrusive igneous rock
AI-generated identification · may be incorrectHardness of 6 on Mohs scale, dark gray to black color, dull to sub-to-glassy luster, microcrystalline to aphanitic crystal structure, and high specific gravity around 2.9.
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Physical properties
Hardness of 6 on Mohs scale, dark gray to black color, dull to sub-to-glassy luster, microcrystalline to aphanitic crystal structure, and high 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, crushed stone for road bases, railroad ballast, and production 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 famous formations like the Giant's Causeway.
Field identification & locations
Identify by its fine-grained dark appearance and heavy weight; found extensively in volcanic regions and oceanic crust worldwide.
