mineral

Smoky Quartz

Silicon Dioxide (SiO2)

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

Hardness: 7 on Mohs scale
Color: Brown to black, smoky gray
Luster: Vitreous

Identified July 4, 2026More mineral →

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Physical properties

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

Formation & geological history

Formed in igneous and metamorphic rocks, particularly pegmatites. The smoky color is caused by natural irradiation of aluminum-bearing quartz over geological time.

Uses & applications

Used in jewelry, as ornamental stones, in crystal healing practices, and as collector specimens. Occasionally used in optical instruments.

Geological facts

Smoky quartz is the national gem of Scotland, where it is known as Cairngorm. It can range from nearly transparent to almost opaque (Morion).

Field identification & locations

Identify by its smoky transparency and crystal habit. Found globally, with notable deposits in Brazil, the Swiss Alps, and the Pikes Peak area of Colorado, USA.