igneous
Basalt River Stone
Aphanitic Basalt
Hardness: 6.0; Color: Dark grey to black; Luster: Dull/Matte; Structure: Microcrystalline; Specific Gravity: 2.8-3.0; Texture: Fine-grained/Aphanitic
- Hardness
- 6
- Color
- Dark grey to black
- Luster
- Dull/Matte
Identified More igneous →
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Physical properties
Hardness: 6.0; Color: Dark grey to black; Luster: Dull/Matte; Structure: Microcrystalline; Specific Gravity: 2.8-3.0; Texture: Fine-grained/Aphanitic
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava at or near the Earth's surface. This specimen has been rounded by fluvial (river) erosion over many years.
Uses & applications
Commonly used in landscaping as river rock, in construction as aggregate for concrete, and occasionally in hot stone massage therapy due to high heat retention.
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 large quantities 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 riverbeds, glacial tills, and coastal areas.
