igneous
Basalt Pebble
Basalt
Hardness: 6.0; Color: Dark grey to black; Luster: Dull/Submetallic; Crystal structure: Aphanitic (fine-grained); Specific gravity: 2.8-3.0
- Hardness
- 6
- Color
- Dark grey to black
- Luster
- Dull/Submetallic
Identified More igneous →
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Physical properties
Hardness: 6.0; Color: Dark grey to black; Luster: Dull/Submetallic; 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 exposed at or very near the surface of a terrestrial planet or a moon. This specimen appears water-worn into a pebble shape.
Uses & applications
Commonly used in construction as aggregate, for road base, concrete, and railroad ballast. Artistically used for river rock landscaping and hot stone massage.
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 on the Moon and Mars.
Field identification & locations
Identify by its dark color, heavy weight for its size, and lack of visible crystals to the naked eye. Often found in riverbeds or volcanic regions.
