igneous
Basalt
Extrusive Igneous Rock
AI-generated identification · may be incorrectHardness of 6 on Mohs scale, dark gray to black color, aphanitic to porphyritic texture, subconchoidal fracture, and specific gravity around 2.8-3.0.
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Physical properties
Hardness of 6 on Mohs scale, dark gray to black color, aphanitic to porphyritic texture, subconchoidal fracture, and specific gravity around 2.8-3.0.
Formation & geological history
Formed from the rapid cooling of low-viscosity, magnesium- and iron-rich lava flows at the Earth's surface. Occurs across oceanic crust and continental volcanic provinces.
Uses & applications
Widely used in construction as crushed aggregate, railroad ballast, dimension stone, and in manufacturing rock wool insulation.
Geological facts
Basalt is the most common volcanic rock type on Earth and also makes up the vast majority of the oceanic crust as well as volcanic plains on the Moon and Mars.
Field identification & locations
Identify by its dark, fine-grained matrix, sometimes containing olivine or plagioclase phenocrysts. Found abundantly in volcanic regions worldwide and oceanic islands.
