mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Brownish-grey, black, or translucent smoke-color; Luster: Vitreous; Crystal Structure: Hexagonal (Trigonal); Cleavage: Indistinct; Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Color: Brownish-grey, black, or translucent smoke-color
Luster: Vitreous

Identified June 17, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Brownish-grey, black, or translucent smoke-color; Luster: Vitreous; Crystal Structure: Hexagonal (Trigonal); Cleavage: Indistinct; Specific Gravity: 2.65

Formation & geological history

Formed in intrusive igneous rocks like granite and in metamorphic rocks. The smoky color is caused by natural irradiation of aluminum-containing quartz over millions of years. Commonly found in pegmatite veins.

Uses & applications

Mainly used in jewelry as beads or faceted gemstones, ornamental carvings, and by crystal collectors for aesthetic and metaphysical purposes.

Geological facts

The smoky color can be artificially induced by exposing clear quartz to radiation, or removed by heating. It was historically used for the first sunglasses in 12th century China to hide the expressions of judges in courts.

Field identification & locations

Identified in the field by its characteristic smoky transparency and lack of cleavage. Found globally, with notable deposits in the Swiss Alps, Brazil, and the United States (Colorado). To identify, look for a glass-like luster that can scratch steel but cannot be scratched by a knife.