mineral

Milky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 Mohs scale; Color: Opaque white; Luster: Vitreous to greasy; Crystal Structure: Trigonal (hexagonal system); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

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

Identified May 25, 2026More mineral →

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Physical properties

Hardness: 7 Mohs scale; Color: Opaque white; Luster: Vitreous to greasy; Crystal Structure: Trigonal (hexagonal system); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Forms through the crystallization of silica-rich hydrothermal solutions or cooling of magma in pegmatites. The white color is caused by microscopic fluid inclusions of gas or liquid trapped during crystal growth.

Uses & applications

Used as a gemstone (cabochons), in glass making, as a source of silicon for electronics, and widely in landscaping and construction gravel.

Geological facts

Milky quartz is the most common variety of crystalline quartz. It is often found in gold-bearing hydrothermal veins, leading old-time miners to refer to it as 'reef' or 'lode' stone.

Field identification & locations

Identify by its hardness (scratches glass), lack of cleavage, and white opaque appearance. Common worldwide in mountain ranges and as river pebbles or beach stones.