igneous
Basalt Pebble
Basalt (Mafic volcanic rock)
Hardness: 6.0 on Mohs scale; Color: Black, dark gray, or dark green; Luster: Dull to waxy; Texture: Aphanitic (fine-grained); Specific Gravity: 2.8–3.0.
- Hardness
- 6
- Color
- Black, dark gray, or dark green
- Luster
- Dull to waxy
Identified More igneous →
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Physical properties
Hardness: 6.0 on Mohs scale; Color: Black, dark gray, or dark green; Luster: Dull to waxy; Texture: 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 near the Earth's surface. This specimen appears water-worn, indicating it was shaped by fluvial or coastal transport.
Uses & applications
Commonly used in construction (rolled aggregates), for hot stone massage therapy, and as decorative landscaping stones.
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 for its size, and absence of visible large crystals. Commonly found on beaches or in riverbeds near volcanic regions.
