mineral

Milky Quartz Pebble

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Opaque white to translucent grey; Luster: Vitreous to greasy; Crystal Structure: Trigonal (Hexagonal); Cleavage: Conchoidal fracture; Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Color: Opaque white to translucent grey
Luster: Vitreous to greasy

Identified June 23, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Opaque white to translucent grey; Luster: Vitreous to greasy; Crystal Structure: Trigonal (Hexagonal); Cleavage: Conchoidal fracture; Specific Gravity: 2.65

Formation & geological history

Formed through the crystallization of silica-rich hydrothermal fluids in veins or as a primary constituent of igneous rocks like granite. This specimen appears water-worn, indicating erosion and transport in a river or coastal environment.

Uses & applications

Used in the manufacturing of glass, abrasives, electronics (piezoelectric properties), landscaping, and as a semi-precious gemstone in jewelry.

Geological facts

Milky quartz gets its white color from millions of tiny fluid inclusions of gas and/or liquid trapped during the crystal's growth. It is the most common variety of crystalline quartz.

Field identification & locations

Identify in the field by its ability to scratch glass (hardness 7), lack of cleavage, and white, waxy appearance. Commonly found in riverbeds, glacial deposits, and mountain outcrops worldwide.