Rock Identifier
Quartz (Milky/Smoky variety) (Silicon Dioxide (SiO2)) — mineral
mineral

Quartz (Milky/Smoky variety)

Silicon Dioxide (SiO2)

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

Hardness
7 on Mohs scale
Color
Translucent white to greyish-tan
Luster
Vitreous to greasy
Identified More mineral

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Physical properties

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

Formation & geological history

Forms in a wide variety of environments, most commonly from the cooling of magma or precipitation from hydrothermal veins. It is a major constituent of granite and many sedimentary rocks.

Uses & applications

Used in glassmaking, electronics (piezoelectric properties), abrasives, and as a gemstones or decorative collectors' pieces.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Its name comes from the German word 'Quarz', which has Slavic origins meaning 'hard'.

Field identification & locations

Identify by its hardness (it can scratch glass), lack of cleavage, and translucent appearance. Found globally in almost all geological environments.