igneous
Basalt River Stone
Basalt
Hardness: 6.0 on Mohs scale; Color: Black to dark gray; Luster: Dull to sub-metallic; Crystal structure: Aphanitic (fine-grained) to porphyritic; Specific gravity: 2.8 - 3.0.
- Hardness
- 6
- Color
- Black to dark gray
- Luster
- Dull to sub-metallic
Identified More igneous →
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Physical properties
Hardness: 6.0 on Mohs scale; Color: Black to dark gray; Luster: Dull to sub-metallic; Crystal structure: Aphanitic (fine-grained) to porphyritic; 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 water erosion in a river or coastal environment.
Uses & applications
Commonly used in landscaping, construction (as aggregate), thermal massage (hot stones), and occasionally for carving or architecture.
Geological facts
Basalt is the most common rock type on Earth's crust and also makes up most of the ocean floors. It is also found on the Moon and Mars.
Field identification & locations
Identify by its characteristic dark color, heavy weight for its size, and the absence of visible large crystals. Commonly found in volcanic regions or along riverbeds downstream from volcanic sources.
