igneous
Basalt (River Stone)
Basalt
Hardness: 6.0; Color: Dark grey to black; Luster: Dull; Crystal structure: Aphanitic (fine-grained); Cleavage: None; Specific gravity: 2.8-3.0
- Hardness
- 6
- Color
- Dark grey to black
- Luster
- Dull
Identified More igneous →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6.0; Color: Dark grey to black; Luster: Dull; Crystal structure: Aphanitic (fine-grained); Cleavage: None; 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 specific specimen has been smoothed by water erosion in a fluvial environment.
Uses & applications
Used extensively in construction as aggregate, for industrial pavers, and as decorative landscaping stones.
Geological facts
Basalt is the most common rock type in the Earth's crust and makes up most of the ocean floor. It also exists on the Moon and Mars.
Field identification & locations
Identify in the field by its heavy weight, dark color, and lack of visible crystals. Commonly found in riverbeds, volcanic regions, and coastal areas.
