igneous
Basalt Beach Pebble
Basalt (Mafic Volcanic Rock)
Hardness: 6 on Mohs scale; Color: Dark grey to olive-green or black; Luster: Dull to sub-vitreous; Structure: Aphanitic (fine-grained); Specific Gravity: 2.8-3.0.
- Hardness
- 6 on Mohs scale
- Color
- Dark grey to olive-green or black
- Luster
- Dull to sub-vitreous
Identified More igneous →
Explore Basalt Beach 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 grey to olive-green or black; Luster: Dull to sub-vitreous; 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 very near the Earth's surface. This specimen has been rounded and smoothed by wave action on a beach.
Uses & applications
Commonly used in crushed form for road base, concrete aggregate, and railroad ballast. Smooth pebbles are used in landscaping and decorative masonry.
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, and weight relative to its size. Commonly found near volcanic coastlines or ancient lava flows. This specimen is a typical 'beach stone' rounded by erosion.
