mineral

Smoky Quartz

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 Mohs; Color: Brownish-grey to black; Luster: Vitreous; Crystal Structure: Hexagonal (trigonal); Cleavage: Indistinct; Specific Gravity: 2.65

Hardness: 7 Mohs
Color: Brownish-grey to black
Luster: Vitreous

Identified July 20, 2026More mineral →

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Physical properties

Hardness: 7 Mohs; Color: Brownish-grey to black; Luster: Vitreous; Crystal Structure: Hexagonal (trigonal); Cleavage: Indistinct; Specific Gravity: 2.65

Formation & geological history

Forms in intrusive igneous and metamorphic rocks, particularly pegmatites. The color is produced by natural irradiation of aluminum-bearing quartz over millions of years.

Uses & applications

Used extensively in jewelry as a gemstone, in ornamental carvings, and by crystal collectors. Historically used for making early sunglasses in China.

Geological facts

The dark color of Smoky Quartz is caused when silicon dioxide is exposed to natural radiation from surrounding radioactive elements like uranium or thorium in the host rock.

Field identification & locations

Identify by its translucent brownish color and glassy luster. It can be found globally, with major deposits in Brazil, Madagascar, and the Swiss Alps.