mineral

Milky Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

Hardness: 7 on Mohs scale; Color: Opaque white (milky); Luster: Vitreous to waxy; Crystal structure: Trigonal/Hexagonal (though tumbled); Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 on Mohs scale
Color: Opaque white (milky)
Luster: Vitreous to waxy

Identified April 22, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Opaque white (milky); Luster: Vitreous to waxy; Crystal structure: Trigonal/Hexagonal (though tumbled); Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Formation & geological history

Formed through the cooling of silica-rich magma or from hydrothermal veins. The milky appearance is caused by tiny inclusions of gas or fluid trapped during crystal growth. This specimen has been smoothed by water erosion or mechanical tumbling.

Uses & applications

Commonly used in landscaping, as abrasive grit, in glass manufacturing, and as a pocket stone or decorative gravel.

Geological facts

Milky quartz is one of the most common mineral varieties on Earth. The white color is due to microscopic 'fluid inclusions'—tiny bubbles of water or carbon dioxide trapped billions of years ago.

Field identification & locations

Identify in the field by its inability to be scratched by a steel knife and its lack of cleavage. It is found globally in riverbeds, beaches, and mountainous outcrops.