sedimentary
Gray River Pebble (likely Limestone or Siltstone)
Sedimentary Rock (Calcium Carbonate or Siliciclastic)
Hardness: 3-5 (Mohs scale); Color: Dull gray; Luster: Matte/Earthy; Structure: Fine-grained, microcrystalline; Cleavage: None (conchoidal to irregular fracture); Specific Gravity: 2.3-2.7
- Hardness
- 3-5 (Mohs scale)
- Color
- Dull gray
- Luster
- Matte/Earthy
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Physical properties
Hardness: 3-5 (Mohs scale); Color: Dull gray; Luster: Matte/Earthy; Structure: Fine-grained, microcrystalline; Cleavage: None (conchoidal to irregular fracture); Specific Gravity: 2.3-2.7
Formation & geological history
Formed through the accumulation of organic debris or mineral particles on sea/lake beds. Its rounded shape indicates extensive water erosion in a high-energy river or beach environment.
Uses & applications
Used in landscaping, construction aggregate (concrete production), and increasingly as canvases for rock painting or decorative home accents.
Geological facts
The smooth texture is the result of 'abrasion,' where the stone collides with other rocks in moving water over decades or centuries.
Field identification & locations
Identify by its smooth, water-worn surface and gray color. Bubbles when touched with weak acid (if limestone). Commonly found in riverbeds and glacial deposits.
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