mineral

Milky Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

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

Hardness: 7 on Mohs scale
Color: Milky white to opaque
Luster: Vitreous to waxy (especially when water-worn)

Identified March 22, 2026More mineral →

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Physical properties

Formation & geological history

Formed from the crystallization of silica-rich hydrothermal fluids in veins or as a late-stage mineral in igneous rocks. This specimen is a 'clastic' pebble, meaning it was weathered from its parent rock and rounded by transport in water (rivers or beaches) over thousands to millions of years.

Uses & applications

Industrial use includes glassmaking and electronics (piezoelectric properties). In the form of river pebbles, it is used extensively in landscaping, drainage, and concrete aggregate. Higher quality milky quartz is used for carvings or beads.

Geological facts

Milky quartz gets its white, cloudy appearance from tiny microscopic inclusions of gas or liquid trapped during the crystal's growth. It is the most common variety of crystalline quartz found on Earth's surface.

Field identification & locations

Identify in the field by its ability to scratch glass (Hardness 7), lack of cleavage, and common water-rounded 'potato' shape in gravel pits or streambeds. Found globally, especially in areas with ancient igneous activity or heavy glacial/alluvial deposits.