igneous
Basalt
Extrusive Igneous Rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, dark gray to black color, dull to fine-grained luster, aphanitic crystal structure with microscopic crystals, and specific gravity around 2.9.
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Physical properties
Hardness of 6 on the Mohs scale, dark gray to black color, dull to fine-grained luster, aphanitic crystal structure with microscopic crystals, and specific gravity around 2.9.
Formation & geological history
Formed from the rapid cooling of low-viscosity, magnesium- and iron-rich lava exposed at or very near the Earth's surface.
Uses & applications
Widely used in construction as crushed stone for road bases, railroad ballast, and aggregate in concrete, as well as in stonemasonry.
Geological facts
Basalt is the most common rock type on the Earth's crust beneath the oceans and also makes up the majority of volcanic islands like Hawaii.
Field identification & locations
Easily identified by its dark, dense, fine-grained appearance and is globally abundant in volcanic provinces and oceanic crust.
