mineral

Quartz Pebble

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale); Color: Milky white to translucent; Luster: Vitreous to waxy (when river-worn); Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); SG: 2.65

Hardness: 7 (Mohs scale)
Color: Milky white to translucent
Luster: Vitreous to waxy (when river-worn)

Identified April 26, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale); Color: Milky white to translucent; Luster: Vitreous to waxy (when river-worn); Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); SG: 2.65

Formation & geological history

Formed from cooling silica-rich hydrothermal fluids or within igneous and metamorphic rocks. This specific specimen has been shaped and smoothed through mechanical erosion in a high-energy aquatic environment, such as a riverbed or beach.

Uses & applications

Used in glassmaking, electronics (piezoelectric properties), abrasives, and as decorative landscaping stone. Smooth pebbles are often used in massage therapy and home decor.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. White 'milky' quartz gets its color from tiny fluid inclusions of gas or liquid trapped during crystal growth.

Field identification & locations

Identify in the field by its hardness (it should easily scratch glass) and lack of cleavage. Look for the smooth, rounded 'egg' shape indicative of water transport found in sedimentary deposits and stream beds.