igneous
Basalt
Mafic extrusive igneous rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, typically dark gray to black in color with an aphanitic or fine-grained texture. It possesses a dull to submetallic luster and lacks prominent visible crystals without magnification.
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Physical properties
Hardness of 6 on the Mohs scale, typically dark gray to black in color with an aphanitic or fine-grained texture. It possesses a dull to submetallic luster and lacks prominent visible crystals without magnification.
Formation & geological history
Formed from the rapid cooling of low-viscosity, magnesium- and iron-rich lava flows at the Earth's surface. It is the most common rock type of oceanic crust.
Uses & applications
Widely used in construction for crushed stone, aggregate in concrete, road base, and in the production of stone wool insulation.
Geological facts
Basalt is the primary volcanic rock found on Earth and also makes up extensive volcanic plains on the Moon and Mars. On Earth, it forms dramatic columnar jointing structures when cooling, such as at the Giant's Causeway.
Field identification & locations
Identified in the field by its dark color, heavy feel due to high iron and magnesium content, and fine-grained matrix. Found globally along oceanic divergent boundaries and continental flood basalt provinces.
