mineral

Milky Quartz

Silicon Dioxide (SiO2)

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

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

Identified July 9, 2026More mineral →

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Physical properties

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

Formation & geological history

Formed through the cooling and crystallization of silica-rich solutions in hydrothermal veins or as a primary constituent in igneous rocks like granite. Its milky appearance is caused by tiny bubbles of gas or liquid trapped during crystal growth.

Uses & applications

Used as a gemstone (decorative), in glass manufacturing, as an abrasive, and in the production of silicon for electronics and solar panels.

Geological facts

Milky quartz is the most common variety of crystalline quartz. It is often found in the vicinity of precious metals like gold in hydrothermal veins. The coordinates provided (Rwanda) are near the Western Rift Valley, an area rich in Precambrian basement rocks and pegmatites where quartz is extremely common.

Field identification & locations

Identify by its hardness (it will easily scratch glass but cannot be scratched by a steel knife), Lack of cleavage, and white 'cloudy' appearance. It is found globally in acidic igneous and metamorphic environments.