mineral

Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

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

Hardness: 7 on Mohs scale
Color: Opaque white (milky)
Luster: Vitreous to greasy

Identified March 22, 2026More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

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

Formation & geological history

Formed through the crystallization of magma or hydrothermal activity in veins. Milky quartz specifically contains tiny fluid inclusions of gas or liquid trapped during crystal growth. They are found across all geological ages.

Uses & applications

Used in glass manufacturing, abrasives, electronics (due to piezoelectric properties), construction aggregate, and as a semi-precious gemstone in jewelry (cabochons or beads).

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. The 'milky' appearance is caused by millions of microscopic bubbles of water or CO2 that scatter light, preventing the crystal from being transparent.

Field identification & locations

Identify in the field by its inability to be scratched by a steel knife (hardness 7) and its lack of cleavage. Common worldwide, especially in mountain ranges and stream beds as 'river rocks'. Collectors look for large, well-formed terminations.