igneous
Basalt River Pebble
Basalt
Hardness: 6.0 on Mohs scale; Color: dark grey to black; Luster: dull/earthy; Crystal structure: aphanitic (fine-grained); Specific gravity: 2.8-3.0
- Hardness
- 6
- Color
- dark grey to black
- Luster
- dull/earthy
Identified More igneous →
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Physical properties
Hardness: 6.0 on Mohs scale; Color: dark grey to black; Luster: dull/earthy; 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 (river) or coastal erosion.
Uses & applications
Commonly used as construction aggregate, road base, and in river rock landscaping. High-quality basalt is used in the manufacturing of stone wool insulation.
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 extensively on the Moon and Mars.
Field identification & locations
Identify by its dark color, heavy weight (density), and lack of visible large crystals. Commonly found in volcanic regions and transported by water to riverbeds.
