igneous
Basalt River Stone
Aphanitic Mafic Volcanic Rock
Hardness: 5-6 Mohs. Color: Charcoal gray to black. Luster: Dull/Matte. Texture: Fine-grained/Aphanitic. Specific Gravity: 2.8-3.0.
- Hardness
- 5-6 Mohs
- Color
- Charcoal gray to black
- Luster
- Dull/Matte
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Physical properties
Hardness: 5-6 Mohs. Color: Charcoal gray to black. Luster: Dull/Matte. Texture: 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 specimen has been naturally tumbled and rounded by water erosion in a river or coastal environment.
Uses & applications
Commonly used in landscaping, as aquarium decor, in hot stone massage therapy, and as a base material in construction (crushed stone).
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 extensively on the Moon and Mars.
Field identification & locations
Identify by its dark color, heavy weight for its size, and lack of visible crystals to the naked eye. Look for smooth, water-worn shapes in riverbeds or beaches.
