igneous
Basalt
Extrusive mafic igneous rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, dark gray to black color, aphanitic to porphyritic texture, and dull luster.
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Physical properties
Hardness of 6 on the Mohs scale, dark gray to black color, aphanitic to porphyritic texture, and dull luster.
Formation & geological history
Formed from the rapid cooling of low-viscosity, magnesium- and iron-rich lava flows at or near Earth's surface.
Uses & applications
Widely used in construction as crushed aggregate, railroad ballast, dimension stone, and for manufacturing rock wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's oceanic crust and also makes up extensive volcanic landforms like the Columbia River Plateaus.
Field identification & locations
Identify by its fine-grained dark matrix, often containing visible phenocrysts of olivine or plagioclase, found extensively in volcanic regions globally.
