igneous
Basalt Pebble
Basalt
Hardness: 6 on Mohs scale. Color: Dark gray to brownish-black. Luster: Dull to earthy. Texture: Fine-grained (aphanitic). Cleavage: None. Specific Gravity: 2.8-3.0.
- Hardness
- 6 on Mohs scale
- Color
- Dark gray to brownish-black
- Luster
- Dull to earthy
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Physical properties
Hardness: 6 on Mohs scale. Color: Dark gray to brownish-black. Luster: Dull to earthy. Texture: Fine-grained (aphanitic). Cleavage: None. Specific Gravity: 2.8-3.0.
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava at or near the Earth's surface. Weathered and rounded over time by water, stream, or beach erosion.
Uses & applications
Commonly used as construction aggregate, road base, and river rock landscaping material. Tumbled pebbles are often used in craft projects or decorative displays.
Geological facts
Basalt is the most common rock type in the Earth's crust, forming the vast majority of the ocean floor and widespread continental flood basalts.
Field identification & locations
Identified by its small size, dark color, fine-grained texture, and smooth, water-worn edges. Commonly found along riverbeds, lakeshores, beaches, and glacial till deposits worldwide.
