mineral

Bull Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Milky white to translucent with yellowish-brown iron staining; Luster: Vitreous to greasy; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Luster: Vitreous to greasy

Identified March 24, 2026More mineral →

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Physical properties

Formation & geological history

Formed from silica-rich hydrothermal fluids cooling in veins and pegmatites. This specimen is likely 'Bull Quartz,' a massive, non-crystalline variety formed deep in the Earth's crust across various geological ages, often found in metamorphic or igneous belts.

Uses & applications

Used as an abrasive in sandblasting, in the manufacturing of glass and ceramics, as a source of silicon for electronics, and commonly as crushed stone for construction and landscaping decoration.

Geological facts

Milky quartz gets its white color from tiny fluid inclusions of gas or liquid trapped during crystal growth. It is one of the most abundant minerals on Earth's surface and is often associated with gold deposits in 'quartz veins.'

Field identification & locations

Identify in the field by its ability to scratch glass, its lack of cleavage (it breaks in irregular, sharp curves), and its greasy luster. It is ubiquitous in riverbeds and mountainous terrain worldwide, particularly in the Appalachian or Rocky Mountains in the US.