igneous
Basalt River Pebble
Basalt (Mafic Volcanic Rock)
Hardness: 5-6 (Mohs); Color: Dark grey to black with possible iron-oxide spots; Luster: Dull to waxy; Texture: Fine-grained (Aphanitic); Specific Gravity: 2.8-3.0
- Hardness
- 5-6 (Mohs)
- Color
- Dark grey to black with possible iron-oxide spots
- Luster
- Dull to waxy
Identified More igneous →
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Physical properties
Hardness: 5-6 (Mohs); Color: Dark grey to black with possible iron-oxide spots; Luster: Dull to waxy; Texture: Fine-grained (Aphanitic); 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 specimen has been rounded by fluvial (river) or coastal erosion over centuries.
Uses & applications
Commonly used in construction (crushed stone), as decorative landscaping rock, or in therapeutic treatments like 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 common on the Moon and Mars.
Field identification & locations
Identify by its weight (dense), dark color, and lack of visible crystals. Commonly found in volcanic regions, riverbeds, and along shorelines.
