mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Brown, grey, to black; Luster: Vitreous (glassy); Crystal Structure: Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Color: Brown, grey, to black
Luster: Vitreous (glassy)

Identified July 7, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Brown, grey, to black; Luster: Vitreous (glassy); Crystal Structure: Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Formed in igneous and metamorphic rocks like granite and gneiss. The color is caused by natural irradiation of aluminum-bearing quartz over millions of years.

Uses & applications

Used primarily in jewelry as a gemstone, in crystal healing practices, and as a popular specimen for mineral collectors.

Geological facts

Smoky quartz is the national gem of Scotland, where it has been mined in the Cairngorm Mountains and called 'Cairngorm stone'. Unlike many other dark gemstones, its color is stable and resistant to fading.

Field identification & locations

Identified by its transparency and distinct brownish-grey 'smoke' color. Commonly found in Brazil, Madagascar, and the USA (Colorado). Real smoky quartz will scratch glass but cannot be scratched by a steel knife.