mineral

Smoky Quartz

SiO2 (Silicon Dioxide with aluminum impurities)

Hardness: 7 on Mohs scale; Color: translucent grey to dark brown/black; Luster: Vitreous; Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Color: translucent grey to dark brown/black
Luster: Vitreous

Identified March 23, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: translucent grey to dark brown/black; Luster: Vitreous; Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Formation & geological history

Formed in igneous or metamorphic rocks (especially granite pegmatites and quartz veins) when natural radiation from surrounding minerals causes substitution of aluminum atoms in the silicon crystal lattice. Aged from millions to billions of years.

Uses & applications

Used in gemstone jewelry (faceted or cabochon), ornamental carvings, crystal healing collections, and historically for some of the earliest sunglasses in 12th century China.

Geological facts

The dark color is the result of natural irradiation. While most specimens are naturally colored, some very dark 'Morion' quartz is produced by artificially irradiating clear quartz. It is the national gem of Scotland, where it is known as Cairngorm.

Field identification & locations

Identify in the field by its smoky translucent color, lack of cleavage, and ability to scratch glass. Commonly found in Brazil, Madagascar, Switzerland, and the United States (Colorado).

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