igneous
River Stone (likely Basalt or Greywacke)
Basalt with mineral veining
Hardness: 6-7 on Mohs scale; Color: Dark grey with white quartz veining; Luster: Dull/Earthy; Crystal structure: Aphanitic (fine-grained); Specific gravity: Approx 2.8-3.0
- Hardness
- 6-7 on Mohs scale
- Color
- Dark grey with white quartz veining
- Luster
- Dull/Earthy
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Dark grey with white quartz veining; Luster: Dull/Earthy; Crystal structure: Aphanitic (fine-grained); Specific gravity: Approx 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. The rounded shape is the result of mechanical weathering and erosion in a river or coastal environment.
Uses & applications
Common river stones are used for decorative landscaping, aquariums, spiritual grounding stones, or as industrial aggregate in construction.
Geological facts
Basalt is the most common rock type in the Earth's crust and covers most of the ocean floor. The white line seen on the rock is a 'leak' of quartz or calcite that filled a crack millions of years ago.
Field identification & locations
Identify in the field by its dark color, heavy weight for its size, and smooth water-worn texture. Often found in riverbeds, glacial till, or beaches.
