igneous
Basalt
Extrusive igneous rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, typically dark gray to black in color, with a dull to sub-woody luster and a fine-grained aphanitic crystal structure.
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Physical properties
Hardness of 6 on the Mohs scale, typically dark gray to black in color, with a dull to sub-woody luster and a fine-grained aphanitic crystal structure.
Formation & geological history
Formed from the rapid cooling of low-viscosity lava rich in iron and magnesium exposed at or very near the Earth's surface.
Uses & applications
Commonly used in construction as crushed aggregate for road bases, railroad ballast, 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 geological formations like the Columbia River Flood Basalts.
Field identification & locations
Easily identified in the field by its dark color, heavy feel, and fine-grained texture, and is widely distributed across volcanic regions globally.
