igneous
Basalt (River Pebble)
Basalt
Hardness: 6; Color: Dark grey to charcoal black; Luster: Dull to sub-vitreous when wet; Crystal Structure: Aphanitic (fine-grained); Specific Gravity: 2.8-3.0
- Hardness
- 6
- Color
- Dark grey to charcoal black
- Luster
- Dull to sub-vitreous when wet
Identified More igneous →
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Physical properties
Hardness: 6; Color: Dark grey to charcoal black; Luster: Dull to sub-vitreous when wet; 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 in a river or coastal environment.
Uses & applications
Commonly used as construction aggregate, road base, 'hot stones' for massage therapy, and in decorative landscaping.
Geological facts
Basalt is the most common rock type in the Earth's crust and makes up most of the ocean floor. The location coordinates provided (Ethiopian Highlands area) are part of a massive volcanic province dominated by basaltic flows.
Field identification & locations
Identify by its heavy weight (relative to size), dark color, and lack of visible large crystals. Extremely common in the East African Rift region.
