igneous
Basalt
Mafic Extrusive Igneous Rock
AI-generated identification · may be incorrectHardness of 6 on Mohs scale, dark gray to black color, dull luster, microcrystalline or aphanitic structure, lacks prominent cleavage, specific gravity around 2.9-3.0.
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Physical properties
Hardness of 6 on Mohs scale, dark gray to black color, dull luster, microcrystalline or aphanitic structure, lacks prominent cleavage, specific gravity around 2.9-3.0.
Formation & geological history
Formed from the rapid cooling of low-viscosity, magnesium- and iron-rich lava flows at the Earth's surface.
Uses & applications
Used extensively in construction as crushed aggregate, railroad ballast, and in the production of stone wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's crust, underlying most ocean basins and forming massive geological features like the Columbia River Plateau.
Field identification & locations
Identified by its dark, fine-grained matrix often containing small visible crystals of plagioclase or olivine; commonly found worldwide in volcanic provinces.
