mineral

Milky Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

Hardness: 7 (Mohs scale), Color: White to translucent milky white, Luster: Vitreous/Greasy, Crystal Structure: Trigonal/Hexagonal, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65

Identified July 18, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale), Color: White to translucent milky white, Luster: Vitreous/Greasy, Crystal Structure: Trigonal/Hexagonal, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65

Formation & geological history

Formed from silica-rich hydrothermal fluids cooling in veins or as a component of igneous rocks. The 'milky' appearance is caused by tiny inclusions of gas or liquid trapped during crystal growth. This specimen appears water-worn, suggesting a fluvial (river) or coastal origin.

Uses & applications

Commonly used in landscaping, road construction as aggregate, glass manufacturing when pure, and as a raw material for silicon chips and solar panels.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Milky quartz's opacity is due to microscopic 'bubbles' of fluid. It is extremely resistant to chemical and physical weathering.

Field identification & locations

Identify by its hardness (it will scratch glass), lack of cleavage, and white color. It is found globally in riverbeds, beaches, and mountain outcrops.