mineral

Milk Quartz (Tumbled Pebble)

Quartz (Silicon Dioxide, SiO2)

Hardness: 7 on Mohs scale; Color: Milky white to translucent cream with faint iron staining; Luster: Vitreous to waxy; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Milky white to translucent cream with faint iron staining
Luster: Vitreous to waxy

Identified March 24, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the cooling of silica-rich hydrothermal fluids in veins or pegmatites. The 'milky' appearance is caused by microscopic fluid inclusions of gas or liquid trapped during crystal growth. This specimen has been smoothed and rounded by water erosion (alluvial) or mechanical tumbling.

Uses & applications

Commonly used as decorative gravel, in landscaping, as pocket stones for collectors, and in the manufacturing of glass and silicon chips when found in high purity.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Milk quartz is the most common variety of crystalline quartz. Historically, it was sometimes used by ancient civilizations for stone tools when flint was unavailable.

Field identification & locations

Identify in the field by its hardness (it will scratch glass/steel), lack of cleavage, and translucent white color. It is found globally in riverbeds, beaches, and mountainous regions. For collectors, look for pieces with minimal staining and interesting fractures.

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