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-withish luster, fine-grained aphanitic crystal structure, 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-withish luster, fine-grained aphanitic crystal structure, specific gravity around 2.9.
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, railroad ballast, aggregate in concrete, and in the production of rock 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 features like the Columbia River Flood Basalts.
Field identification & locations
Identified by its dense, dark, fine-grained matrix and commonly found in volcanic regions, oceanic islands, and continental flood basalt provinces.
