mineral

Quartz pebble (Chert / Chalcedony)

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

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

Identified July 27, 2026More mineral →

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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.