igneous
Basalt
Extrusive Igneous Rock
Hardness: 5-6 on Mohs scale, Color: Dark grey to black, Luster: Dull to sub-earthy, Crystal structure: Aphanitic (fine-grained) with microcrystalline texture, Specific Gravity: 2.8-3.0
Identified More igneous →
Explore Basalt in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 5-6 on Mohs scale, Color: Dark grey to black, Luster: Dull to sub-earthy, Crystal structure: Aphanitic (fine-grained) with microcrystalline texture, Specific Gravity: 2.8-3.0
Formation & geological history
Formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a planet or moon.
Uses & applications
Used in construction as crushed stone for road bases, concrete aggregate, railroad ballast, and in the production of basalt fiber.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the ocean basins and also makes up significant portions of the volcanic provinces on the Moon and Mars.
Field identification & locations
Identify by its dark, fine-grained appearance, often heavy weight due to iron and magnesium content. Commonly found in volcanic regions worldwide.
