mineral

Quartz Pebble

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale); Color: Translucent white to milky; Luster: Vitreous to waxy (when water-worn); Crystal structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 (Mohs scale)
Color: Translucent white to milky
Luster: Vitreous to waxy (when water-worn)

Identified March 11, 2026More mineral →

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Physical properties

Formation & geological history

Formed from the crystallization of silica-rich magma or precipitation from hydrothermal fluids. This specific rounded shape results from mechanical weathering and abrasion in high-energy environments like riverbeds or ocean beaches over thousands of years.

Uses & applications

Used widely in glassmaking, grit for sandblasting, and as a component in concrete. Smooth pebbles are popular in landscaping, aquarium decor, and as 'worry stones'. Low-quality pebbles are used as industrial abrasive.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. These rounded specimens are often called 'river rocks' or 'sea glass' equivalents of the mineral world and can survive for millions of years due to their high chemical and physical stability.

Field identification & locations

Identify in the field by its inability to be scratched by a steel knife (H=5.5) and its lack of cleavage planes. Translucent milky appearance and smooth, rounded edges are diagnostic for water-worn quartz. Found globally in almost any river or coastal environment.