igneous
Basalt Pebble
Basalt (Mafic volcanic rock)
Hardness: 6; Color: Dark grey to black with reddish oxidized spots; Luster: Dull to sub-metallic; Structure: Fine-grained aphanitic; Specific Gravity: 2.8–3.0.
- Hardness
- 6
- Color
- Dark grey to black with reddish oxidized spots
- Luster
- Dull to sub-metallic
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; Color: Dark grey to black with reddish oxidized spots; Luster: Dull to sub-metallic; Structure: Fine-grained aphanitic; 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 pebble has been rounded by fluvial or wave action over time.
Uses & applications
Larger quantities are used in construction for aggregate, road base, and concrete; small pebbles are often used in landscaping or as aquarium decor.
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
Identified by its dark color, heavy weight for its size, and absence of visible crystals without magnification. Commonly found on volcanic beaches and in riverbeds.
