igneous
Basalt Pebble
Extrusive igneous rock
Hardness: 6 on Mohs scale; Color: Dark gray to black; Luster: Dull to sub-vitreous; Crystal structure: Aphanitic (fine-grained), often containing microscopic crystals of plagioclase feldspar and pyroxene.
- Hardness
- 6 on Mohs scale
- Color
- Dark gray to black
- Luster
- Dull to sub-vitreous
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: 6 on Mohs scale; Color: Dark gray to black; Luster: Dull to sub-vitreous; Crystal structure: Aphanitic (fine-grained), often containing microscopic crystals of plagioclase feldspar and pyroxene.
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, typically originating from volcanic eruptions or oceanic crust formation.
Uses & applications
Used in construction as crushed aggregate, railroad ballast, and dimension stone, as well as in basalt fiber manufacturing.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the world's oceans and also makes up extensive volcanic formations on the Moon and Mars.
Field identification & locations
Commonly found in stream beds and along beaches where water action has smoothed and rounded the fragments; identifiable by its dark color, heavy feel relative to its size, and fine-grained texture.
