mineral

Quartz Vein in Host Rock

Silicon Dioxide (SiO2)

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

Hardness: 7 (Mohs scale)
Color: White to translucent grey (milky quartz)
Luster: Vitreous to greasy

Identified March 27, 2026More mineral →

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Physical properties

Formation & geological history

Formed through hydrothermal processes where silica-rich hot fluids circulate through fractures in crustal rocks (host rocks). As the fluids cool or change pressure, the quartz precipitates and fills the cracks. These can form across any geological age from Archean to recent.

Uses & applications

Industrial source of silica for glass and electronics; gold and other precious metals are often found within these veins; construction aggregate; lapidary use for jewelry and carvings.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. 'Milky quartz' gets its white color from tiny fluid inclusions of gas and/or liquid trapped during crystal growth.

Field identification & locations

Identify in the field by its superior hardness (cannot be scratched by a steel knife), glassy luster compared to surrounding rock, and lack of cleavage (it breaks in irregular, shell-like curves). Common in mountainous or metamorphic terrains.