mineral

Smoky Quartz (with complementary stones in jewelry setting)

Smoky Quartz (Silicon Dioxide - SiO2)

Hardness: 7 on Mohs scale; Color: Brownish-grey to black; Luster: Vitreous; Crystal structure: Hexagonal (trigonal); Cleavage: Indistinct; Specific gravity: 2.65.

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

Identified March 30, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Brownish-grey to black; Luster: Vitreous; Crystal structure: Hexagonal (trigonal); Cleavage: Indistinct; Specific gravity: 2.65.

Formation & geological history

Formed in igneous or metamorphic rocks like granite and gneiss, specifically within pegmatite veins. The smoky color is caused by natural irradiation of trace aluminum impurities.

Uses & applications

Used primarily as a gemstone for jewelry, carvings, and ornamental spheres. Also historically used in early sunglasses in 12th century China.

Geological facts

Smoky quartz is the national gem of Scotland, where it is often referred to as 'Cairngorm' after the Cairngorm Mountains where it is found.

Field identification & locations

Identify in the field by its distinct smoky transparency and lack of cleavage (conchoidal fracture). Commonly found in Brazil, Madagascar, and the Swiss Alps.

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