igneous
Basalt
Extrusive mafic igneous rock
AI-generated identification · may be incorrectHardness 6 on Mohs scale, dark gray to black color, dull luster, fine-grained aphanitic crystal structure, lacks prominent cleavage, specific gravity around 2.9.
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Physical properties
Hardness 6 on Mohs scale, dark gray to black color, dull luster, fine-grained aphanitic crystal structure, lacks prominent cleavage, specific gravity around 2.9.
Formation & geological history
Formed from the rapid cooling of low-viscosity, magnesium- and iron-rich lava flows at the Earth's surface, often during volcanic activity spanning various geological eras.
Uses & applications
Used extensively in construction as crushed stone for road bases, concrete aggregate, and manufacturing stone wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the world's ocean basins and forms major planetary features like the lunar maria.
Field identification & locations
Identify by its dark color and very fine-grained matrix where individual minerals are barely visible without a hand lens. Common globally in volcanic provinces.
