igneous
Basalt
Extrusive igneous rock
AI-generated identification · may be incorrectHardness 6 on Mohs scale, dark gray to black color, dull to sub-withering luster, fine-grained aphanitic crystal structure, no visible cleavage.
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Physical properties
Hardness 6 on Mohs scale, dark gray to black color, dull to sub-withering luster, fine-grained aphanitic crystal structure, no visible cleavage.
Formation & geological history
Formed from the rapid cooling of low-viscosity basaltic 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 manufacturing railroad ballast.
Geological facts
Basalt is the most common rock type in the Earth's crust, making up most of the oceanic crust and volcanic islands like Hawaii.
Field identification & locations
Identified by its dark, dense, fine-grained appearance, often found in volcanic regions, oceanic ridges, and flood basalt provinces.
