igneous
Basalt Pebble
Basalt
Hardness: 6.0; Color: Dark grey to black; Luster: Dull/Earthy; Crystal Structure: Aphanitic (fine-grained); Cleavage: None; Specific Gravity: 2.8-3.0
- Hardness
- 6
- Color
- Dark grey to black
- Luster
- Dull/Earthy
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Physical properties
Hardness: 6.0; Color: Dark grey to black; Luster: Dull/Earthy; Crystal Structure: Aphanitic (fine-grained); 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. This specimen has been rounded by fluvial or marine erosion.
Uses & applications
Construction aggregate, road base, stone carvings, and massage stones due to their heat retention properties.
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 prevalent on the Moon and Mars.
Field identification & locations
Identified by its dark color, heavy weight for its size, and absence of visible crystals. Commonly found on beaches and in riverbeds in volcanic regions.
