igneous
Basalt
Extrusive Igneous Rock
Hardness of 6 on the Mohs scale, dark gray to black color, fine-grained aphanitic texture, dull to submetallic luster, specific gravity around 2.8 to 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 of 6 on the Mohs scale, dark gray to black color, fine-grained aphanitic texture, dull to submetallic luster, specific gravity around 2.8 to 3.0.
Formation & geological history
Formed from the rapid cooling of low-viscosity lava rich in iron and magnesium exposed at or very near the Earth's surface, often associated with volcanic activity and oceanic crust.
Uses & applications
Used in construction, aggregate for concrete, road base, asphalt pavement, and sometimes carved into tiles or monuments.
Geological facts
Basalt is the most common rock type in the Earth's crust and makes up most of the oceanic crust as well as major volcanic features on the Moon and Mars.
Field identification & locations
Easily identified by its dark, fine-grained appearance, heavy weight relative to size, and frequent presence in volcanic regions or river beds.
