igneous
Basalt Pebble
Basalt
Hardness: 6 on Mohs scale; Color: Dark grey to black with tiny lighter mineral grains; Luster: Dull to earthy; Texture: Fine-grained (aphanitic), stream-rounded pebble.
- Hardness
- 6 on Mohs scale
- Color
- Dark grey to black with tiny lighter mineral grains
- Luster
- Dull to earthy
Identified More igneous →
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Physical properties
Hardness: 6 on Mohs scale; Color: Dark grey to black with tiny lighter mineral grains; Luster: Dull to earthy; Texture: Fine-grained (aphanitic), stream-rounded pebble.
Formation & geological history
Formed from the rapid cooling of low-viscosity magnesium- and iron-rich lava at or near Earth's surface. Rounded by river or wave abrasion.
Uses & applications
Commonly used in construction aggregate, road base, landscaping, and ballast, though small individual stream pebbles have no commercial value.
Geological facts
Basalt is the most common rock type in the Earth's crust, forming almost the entire ocean floor as well as massive flood basalt provinces on land.
Field identification & locations
Identified by its dark coloration, fine-grained texture, and water-worn smooth shape. Commonly found along riverbeds, beaches, and volcanic areas.
