igneous
Basalt Pebble
Basalt (Mafic Extrusive Volcanic Rock)
Hardness: 6 (Mohs scale); Color: Dark grey to black with brownish weathering (iron oxidation); Luster: Dull/Earthy; Crystal structure: Aphanitic (fine-grained); Specific gravity: 2.8-3.0
- Hardness
- 6 (Mohs scale)
- Color
- Dark grey to black with brownish weathering (iron oxidation)
- Luster
- Dull/Earthy
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 (Mohs scale); Color: Dark grey to black with brownish weathering (iron oxidation); Luster: Dull/Earthy; Crystal structure: Aphanitic (fine-grained); Specific gravity: 2.8-3.0
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava at or near the Earth's surface. This specific specimen has been water-worn into a smooth pebble shape, likely in a river or coastal environment.
Uses & applications
Common basalt is used as construction aggregate, road base, and in concrete; small smooth pebbles are used for decorative landscaping or aquarium gravel.
Geological facts
Basalt is the most common rock type in the Earth's crust and makes up most of the ocean floor. It is also found on the Moon and Mars.
Field identification & locations
Identify by its dark color, fine grain (crystals too small to see with the naked eye), and heavy feel for its size. It is commonly found in volcanic regions or transported far by water.
