igneous
Basalt
Extrusive Igneous Rock
AI-generated identification · may be incorrectHardness of 6 on Mohs scale, typically dark gray to black, dull luster, fine-grained aphanitic crystal structure, and high specific gravity around 2.8-3.0.
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Physical properties
Hardness of 6 on Mohs scale, typically dark gray to black, dull luster, fine-grained aphanitic crystal structure, and high specific gravity around 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
Widely used in construction as crushed stone for road bases, concrete aggregate, and in the manufacturing of rock wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's crustal portions underlying the ocean basins and also forms massive volcanic structures like the Giant's Causeway.
Field identification & locations
Identify in the field by its dark, fine-grained matrix and heavy feel; commonly found globally in volcanic provinces and oceanic crustal regions.
