igneous
Basalt
Mafic extrusive igneous rock
AI-generated identification · may be incorrectHardness 6 on Mohs scale, dark black to gray color, fine-grained aphanitic texture, specific gravity 2.8-3.0.
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Physical properties
Hardness 6 on Mohs scale, dark black to gray color, fine-grained aphanitic texture, specific gravity 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.
Uses & applications
Used widely in construction aggregates, road base, railroad ballast, and dimension stone.
Geological facts
Basalt is the most common rock type on Earth's crust, forming the primary rock of ocean floors and major volcanic islands like Hawaii.
Field identification & locations
Identify by its dark, dense, fine-grained matrix, often vesicular or porphyritic; found globally in volcanic provinces.
