igneous
Basalt River Stone
Basalt (Mafic volcanic rock)
Hardness: 6.0 on Mohs scale; Color: Black to dark grey; Luster: Dull or earthy; Structure: Aphanitic (fine-grained); Specific Gravity: 2.8-3.0; Texture: Smooth due to water erosion.
- Hardness
- 6
- Color
- Black to dark grey
- Luster
- Dull or earthy
Identified More igneous →
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Physical properties
Hardness: 6.0 on Mohs scale; Color: Black to dark grey; Luster: Dull or earthy; Structure: Aphanitic (fine-grained); Specific Gravity: 2.8-3.0; Texture: Smooth due to water erosion.
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 shaped and smoothed by fluvial (river) or coastal water action over thousands of years.
Uses & applications
Used in landscaping, decorative river rock gardens, massage stone therapy, aquarium decor, and as an aggregate in construction and road building.
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 in abundance on the Moon and Mars.
Field identification & locations
Identify in the field by its dark color, heavy weight for its size, and lack of visible crystals. It is ubiquitous in volcanic regions and along riverbeds downstream from volcanic mountain ranges.
