igneous
Basalt River Stone
Basalt
Hardness: 6-7 (Mohs scale); Color: Dark grey to black, weathering to brown; Luster: Dull to earthy; Crystal structure: Aphanitic (fine-grained); Specific gravity: 2.8-3.0
- Hardness
- 6-7 (Mohs scale)
- Color
- Dark grey to black, weathering to brown
- Luster
- Dull to earthy
Identified More igneous →
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Physical properties
Hardness: 6-7 (Mohs scale); Color: Dark grey to black, weathering to brown; Luster: Dull to earthy; 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. This specific specimen has been rounded and smoothed by water erosion (alluvial action) over thousands of years.
Uses & applications
Used widely in construction (crushed stone), decorative landscaping, massage therapy (hot stones), and as an abrasive in industrial applications.
Geological facts
Basalt is the most common rock in 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 heavy weight (density), dark color, and fine-grained texture. Commonly found in riverbeds near volcanic regions or as decorative landscape gravel.
