mineral

Bull Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale); Color: White to smoky grey/blue; Luster: Vitreous to greasy; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 (Mohs scale)
Color: White to smoky grey/blue
Luster: Vitreous to greasy

Identified April 21, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale); Color: White to smoky grey/blue; Luster: Vitreous to greasy; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Formed through the cooling of hydrothermal fluids in veins or as a late-stage crystallization in igneous pegmatites. This massive variety lacks well-defined crystal faces due to rapid or crowded growth.

Uses & applications

Used in the production of glass, ceramics, and abrasives. Historically used for stone tools. Lesser grades are used for landscaping or construction aggregate.

Geological facts

Milky quartz gets its cloudy appearance from tiny fluid inclusions of gas or liquid trapped during crystal growth. It is one of the most abundant minerals in the Earth's crust.

Field identification & locations

Identify by its ability to scratch glass, its lack of cleavage, and its waxy/greasy luster on broken surfaces. Often found in gold-bearing regions as 'vein quartz'.