igneous
Basalt
Extrusive igneous rock
AI-generated identification · may be incorrectHardness 6 on Mohs scale; dark gray to black color; dull to sub-to-glassy luster; fine-grained aphanitic crystal structure with no visible crystals.
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Physical properties
Hardness 6 on Mohs scale; dark gray to black color; dull to sub-to-glassy luster; fine-grained aphanitic crystal structure with no visible crystals.
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 aggregate for roads, railroad ballast, 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 formations like the Columbia River Flood Basalts.
Field identification & locations
Identified by its dark color, heavy weight, and fine-grained texture; commonly found in volcanic regions and oceanic crusts worldwide.
