mineral
Quartz pebble (Chert / Chalcedony)
Silicon Dioxide (SiO2)
Hardness: 7 on Mohs scale; Color: brownish-tan, semi-translucent; Luster: waxy to vitreous; Crystal Structure: Trigonal/Microcrystalline; Cleavage: none (conchoidal fracture); Specific Gravity: ~2.65
- Hardness
- 7 on Mohs scale
- Color
- brownish-tan, semi-translucent
- Luster
- waxy to vitreous
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Physical properties
Hardness: 7 on Mohs scale; Color: brownish-tan, semi-translucent; Luster: waxy to vitreous; Crystal Structure: Trigonal/Microcrystalline; Cleavage: none (conchoidal fracture); Specific Gravity: ~2.65
Formation & geological history
Formed via precipitation of silica-rich fluids in sedimentary or volcanic environments, later weathered, rounded, and smoothed by water transport in rivers or ocean shores.
Uses & applications
Commonly collected as river rocks, used in lapidary work, landscape gravel, or tumbled into decorative polished stones.
Geological facts
Water-worn quartz and chert pebbles are among the most durable rocks on Earth, surviving millions of years of erosion due to their high resistance to mechanical and chemical weathering.
Field identification & locations
Identify in the field by its hardness (scratches glass easily), smooth rounded shape, waxy appearance, and translucent light transmission when held to a bright light source. Found in stream beds, beaches, and glacial deposits worldwide.
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