sedimentary
River Pebble
Polished Quartzite / Siliceous River Pebble
Hardness: 7 on Mohs scale; Color: Brown, tan, and gray shades; Luster: Vitreous to waxy when polished; Crystal structure: Microcrystalline (Cryptocrystalline quartz); Cleavage: None (conchoidal fracture); Specific gravity: 2.65
- Hardness
- 7 on Mohs scale
- Color
- Brown, tan, and gray shades
- Luster
- Vitreous to waxy when polished
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Physical properties
Hardness: 7 on Mohs scale; Color: Brown, tan, and gray shades; Luster: Vitreous to waxy when polished; Crystal structure: Microcrystalline (Cryptocrystalline quartz); Cleavage: None (conchoidal fracture); Specific gravity: 2.65
Formation & geological history
Formed through the weathering, erosion, and water-transport of parent rocks (typically quartz-rich sandstone or quartzite) along riverbeds and coastal environments over thousands to millions of years.
Uses & applications
Used in landscaping, decorative gravel, garden pathways, tumbling, and amateur rock collecting.
Geological facts
Water tumbling is nature's original rock tumbler, smoothing sharp edges and polishing surfaces through continuous abrasion with sand and other pebbles in fast-flowing water.
Field identification & locations
Found worldwide in riverbeds, streams, and beaches. Easily identified by its smooth, rounded shape and hard, scratch-resistant surface that does not effervesce with acid.
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