mineral

Milky Quartz Pebble

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Milky white to opaque; Luster: Vitreous to greasy; 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 greasy

Identified July 18, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Milky white to opaque; Luster: Vitreous to greasy; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Forms in hydrothermal veins or as a late-stage mineral in igneous rocks like granite. This specimen appears water-worn, likely tumbled in a river or ocean over thousands of years. Scale of age varies by location, often millions of years old.

Uses & applications

Industrial use for glass making, abrasives, and electronics (as a source of silicon); also used in decorative landscaping and as cheap gravel.

Geological facts

The milky white color is caused by tiny 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

Identified by its white color, inability to be scratched by a steel blade, and lack of cleavage. Commonly found in riverbeds, beaches, and eroded soil worldwide.