mineral

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Hardness: 7 on Mohs scale; Color: White to opaque (cloudy); Luster: Vitreous (glassy) to greasy; Crystal Structure: Trigonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Color: White to opaque (cloudy)
Luster: Vitreous (glassy) to greasy

Identified March 7, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: White to opaque (cloudy); Luster: Vitreous (glassy) to greasy; Crystal Structure: Trigonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Forms in hydrothermal veins, pegmatites, and as a primary constituent in igneous rocks like granite. The 'milky' appearance is caused by tiny inclusions of liquid or gas trapped during crystal growth. Found in deposits ranging from Precambrian to recent geological ages.

Uses & applications

Used as an abrasive in sandblasting, in glassmaking, as a component in concrete, and for landscaping. Lower-grade milky quartz is often used in garden paths, while high-purity pieces are used in the semiconductor industry.

Geological facts

Milky quartz is the most common variety of crystalline quartz. Historically, it has been used for stone tools and as a decorative stone in many cultures. It is often found associated with gold in quartz veins, making it a primary indicator for prospectors.

Field identification & locations

Identify in the field by its hardness (it will scratch glass/steel), lack of cleavage, and white opaque appearance. Frequently found in riverbeds, mountains, and outcroppings worldwide, particularly in areas with tectonic activity.