igneous
Basalt River Stone
Basalt
Hardness: 6 (Mohs); Color: Dark brown to black; Luster: Dull to sub-vitreous; Crystal structure: Aphanitic (fine-grained); Specific gravity: 2.8–3.0.
- Hardness
- 6 (Mohs)
- Color
- Dark brown to black
- Luster
- Dull to sub-vitreous
Identified More igneous →
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Physical properties
Hardness: 6 (Mohs); Color: Dark brown to black; Luster: Dull to sub-vitreous; 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 very near the Earth's surface. This specific specimen has been smoothed by water erosion in a river or beach environment.
Uses & applications
Commonly used in landscaping, as aquarium decor, in construction for road base or concrete aggregate, and occasionally in stone massage therapy.
Geological facts
Basalt is the most common volcanic rock on Earth and also makes up most of the ocean floor. It is found on the Moon and Mars as well.
Field identification & locations
Identify by its weight (dense for its size), dark color, and fine-grained texture. It often weathers to a brownish color due to iron oxidation.
