mineral

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

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

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

Identified July 7, 2026More mineral →

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Physical properties

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

Formation & geological history

Formed from hydrothermal veins or late-stage cooling of silica-rich magma (igneous) or through metamorphic processes. This specimen likely originates from the Sierra Nevada foothills or Sacramento Valley river gravels.

Uses & applications

Used as an abrasive, in glass manufacturing, as a source for silicon, in landscaping, and as a popular specimen for mineral collectors.

Geological facts

The milky white color is caused by tiny inclusions of gas or liquid trapped during the crystal's initial formation. It is the most common variety of crystalline quartz found on Earth's crust.

Field identification & locations

Identify in the field by its hardness (will scratch glass), lack of cleavage, and white color. Found extensively in the regional gravels and gold-bearing quartz veins of Northern California (Mother Lode region).