metamorphic
Banded River Pebble (Gneiss or Quartz-Veined Basalt)
Polished River Siltstone or Quartzite Gneiss
Hardness: 6-7 (Mohs scale); Color: Dark grey/green matrix with a tan/peach band; Luster: Dull to waxy; Texture: Fine-grained, rounded by water erosion.
- Hardness
- 6-7 (Mohs scale)
- Color
- Dark grey/green matrix with a tan/peach band
- Luster
- Dull to waxy
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Physical properties
Hardness: 6-7 (Mohs scale); Color: Dark grey/green matrix with a tan/peach band; Luster: Dull to waxy; Texture: Fine-grained, rounded by water erosion.
Formation & geological history
Formed through the combination of regional metamorphism and subsequent water erosion. The light band likely represents a quartz or feldspar vein that intruded the darker host rock before being smoothed in a high-energy river or beach environment.
Uses & applications
Primarily used for decorative purposes in landscaping, aquariums, or as a pocket stone for collectors. No significant industrial value.
Geological facts
This specimen is a 'water-worn' pebble, meaning its smooth surface is the result of thousands of years of mechanical weathering by water and sand. The sharp boundary between colors highlights a geological 'contact zone'.
Field identification & locations
Identify by its distinct color banding and smooth, ovate shape. Commonly found in riverbeds, glacial tills, and coastal beaches. Collectors look for high contrast and symmetrical banding.
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