mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Translucent grey to brownish-black; Luster: Vitreous; Crystal system: Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

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

Identified May 16, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Translucent grey to brownish-black; Luster: Vitreous; Crystal system: Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Formation & geological history

Formed in intrusive igneous rocks such as granite or pegmatites. The smoky color results from natural irradiation of aluminum-bearing quartz over geological time.

Uses & applications

Used extensively in jewelry as gemstones, in decorative carvings, and as a popular specimen for mineral collectors. Historically used for protective amulets.

Geological facts

The earliest 'sunglasses' were made from flat panes of smoky quartz in 12th century China. The color can be deepened through artificial irradiation or lightened through heating.

Field identification & locations

Identified by its dark translucent color and crystal habit. Found globally in mountainous regions, with notable deposits in the Swiss Alps, Brazil, and the United States (Pikes Peak, CO).