igneous
Basalt
Mafic extrusive igneous rock
AI-generated identification · may be incorrectHardness 6 on Mohs scale, dark gray to black color, aphanitic to glassy luster, fine-grained microcrystalline structure, high specific gravity around 2.9-3.0.
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Physical properties
Hardness 6 on Mohs scale, dark gray to black color, aphanitic to glassy luster, fine-grained microcrystalline structure, high specific gravity around 2.9-3.0.
Formation & geological history
Formed from the rapid cooling of low-viscosity basaltic lava flows 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 manufacturing of stone wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's oceanic crust and also forms extensive continental flood basalt provinces.
Field identification & locations
Identified by its dark color, heavy weight, and fine-grained texture; commonly found worldwide in volcanic regions and ocean floors.
