igneous
Basalt
Mafic extrusive igneous rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, dark gray to black color, dull luster, microcrystalline to aphanitic structure, specific gravity around 2.8-3.0.
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Physical properties
Hardness of 6 on the Mohs scale, dark gray to black color, dull luster, microcrystalline to aphanitic structure, specific gravity around 2.8-3.0.
Formation & geological history
Formed from the rapid cooling of low-viscosity, iron- and magnesium-rich lava flows at the Earth's surface, often originating from oceanic crust or volcanic islands.
Uses & applications
Used extensively in construction as crushed stone for road bases, concrete aggregate, and in the production of rock wool insulation.
Geological facts
Basalt is the most common volcanic rock type on Earth, and it also makes up the vast majority of the underlying oceanic crust and lunar maria.
Field identification & locations
Identify in the field by its dark, fine-grained groundmass and heavy weight; commonly found in volcanic regions, rift zones, and oceanic divergent boundaries worldwide.
