igneous
Basalt Pebble
Extrusive Igneous Rock
Hardness of 6 on the Mohs scale, dark gray to black color, fine-grained (aphanitic) crystal structure, dull to sub-metallic luster, specific gravity around 2.8 - 3.0
Identified More igneous →
Explore Basalt Pebble 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) crystal structure, dull to sub-metallic luster, specific gravity around 2.8 - 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.
Uses & applications
Used in construction as crushed stone, railroad ballast, aggregate in concrete, and sometimes in stonemasonry or landscaping.
Geological facts
Basalt is the most common rock type in the Earth's oceanic crust and is also found abundantly on the Moon and Mars.
Field identification & locations
Easily identified by its dark, fine-grained appearance, water-smoothed rounded shape from wave action, and high density.
