igneous
Basalt
Extrusive igneous rock
AI-generated identification · may be incorrectHardness of 6 on Mohs scale, dark gray to black color, dull to sub-aphanitic luster, fine-grained aphanitic crystal structure, and high 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-aphanitic luster, fine-grained aphanitic crystal structure, and high specific gravity around 2.9.
Formation & geological history
Formed from the rapid cooling of low-viscosity, magnesium- and iron-rich lava exposed at or near the Earth's surface.
Uses & applications
Widely used in construction, road base, asphalt production, and as crushed stone for railroad ballast.
Geological facts
Basalt is the most common rock type in the Earth's oceanic crust and is also found forming extensive lava plateaus on land.
Field identification & locations
Identified by its dark color, fine-grained texture, and heavy weight; commonly found in volcanic regions worldwide.
