igneous
Basalt
Extrusive Igneous Rock
Hardness: 6 on the Mohs scale, Color: Dark grey to black, Luster: Dull to sub-vitreous, Crystal structure: Aphanitic (fine-grained), 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: 6 on the Mohs scale, Color: Dark grey to black, Luster: Dull to sub-vitreous, Crystal structure: Aphanitic (fine-grained), Specific gravity: 2.8-3.0
Formation & geological history
Formed from the rapid cooling of low-viscosity lava rich in magnesium and iron exposed at or very near the surface of a planet or moon.
Uses & applications
Used in construction, aggregate for roads, making rock wool insulation, and manufacturing tiles.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the ocean basins and is also found abundantly on the Moon and Mars.
Field identification & locations
Easily identified by its dark, fine-grained appearance, often smooth or rounded from water transport if found in riverbeds or beaches.
