igneous
Basalt
Extrusive mafic igneous rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, dark gray to black in color, dull luster, aphanitic crystal structure, and high specific gravity around 2.9.
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Physical properties
Hardness of 6 on the Mohs scale, dark gray to black in color, dull luster, 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 flows at the Earth's surface.
Uses & applications
Widely used in construction as crushed aggregate, railroad ballast, and dimension stone.
Geological facts
Basalt is the most common rock type in the Earth's oceanic crust and also forms extensive continental flood basalts.
Field identification & locations
Identify by its dark, fine-grained appearance, often containing small vesicles or phenocrysts, found globally in volcanic regions.
