igneous
Basalt River Pebble
Basalt
Hardness: 6; Color: Dark grey to black; Luster: Dull to sub-metallic; Crystal structure: Aphanitic (fine-grained); Specific Gravity: 2.8 - 3.0
- Hardness
- 6
- Color
- Dark grey to black
- Luster
- Dull to sub-metallic
Identified More igneous →
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Physical properties
Hardness: 6; Color: Dark grey to black; Luster: Dull to sub-metallic; 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 rounded by fluvial erosion in a river or stream.
Uses & applications
Commonly used as construction aggregate, road base, and decorative landscaping stones. Smooth pebbles are often used in massage therapy and home decor.
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
Identified by its dark color, heavy weight compared to similar sized sedimentary rocks, and fine-grained texture. Commonly found in volcanic regions and riverbeds transporting volcanic material.
