igneous
Basalt Pebble
Aphanitic mafic extrusive rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, dark grey to black color, dull luster, fine-grained microcrystalline structure, and high density.
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Physical properties
Hardness of 6 on the Mohs scale, dark grey to black color, dull luster, fine-grained microcrystalline structure, and high density.
Formation & geological history
Formed from the rapid cooling of low-viscosity, magnesium- and iron-rich lava flows at the Earth's surface.
Uses & applications
Commonly used in construction aggregate, railroad ballast, and decorative landscaping stones.
Geological facts
Basalt is the most common rock type in the Earth's oceanic crust and also makes up major volcanic features on the Moon and Mars.
Field identification & locations
Identified by its dark color, heavy weight, and very fine-grained texture; easily found on beaches and riverbeds worldwide.
