igneous
Basalt River Stone
Basalt
Hardness: 6; Color: Dark grey to black; Luster: Dull/Matte; Crystal structure: Aphanitic (fine-grained); Specific gravity: 2.8-3.0
- Hardness
- 6
- Color
- Dark grey to black
- Luster
- Dull/Matte
Identified More igneous →
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Physical properties
Hardness: 6; Color: Dark grey to black; Luster: Dull/Matte; 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 specimen has been rounded by fluvial (river) or glacial transport.
Uses & applications
Used primarily in construction aggregate, road base, and as decorative landscaping stones. Highly polished versions are used in massage therapy (hot stones).
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 on the Moon and Mars.
Field identification & locations
Identify by its dark color, heavy weight for its size, and fine-grained texture. Commonly found in volcanic regions or as rounded cobbles in riverbeds.
