mineral

Smoky Quartz

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 (Mohs scale), Color: Smoky brown to black/grey, Luster: Vitreous (glassy), Crystal system: Hexagonal (trigonal), Cleavage: None (conchoidal fracture), Specific Gravity: 2.65

Identified June 13, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale), Color: Smoky brown to black/grey, Luster: Vitreous (glassy), Crystal system: Hexagonal (trigonal), Cleavage: None (conchoidal fracture), Specific Gravity: 2.65

Formation & geological history

Formed in igneous and metamorphic rocks, particularly pegmatites. The smoky color results from natural irradiation of aluminum-bearing quartz over long geological periods.

Uses & applications

Used in jewelry, decorative carvings, and as a popular specimen for mineral collectors. Historically used for one of the first types of sunglasses in China.

Geological facts

The dark color is caused by free silicon formed from silicon dioxide by natural irradiation. Cairngorm is a famous variety of smoky quartz found in the Cairngorm Mountains of Scotland.

Field identification & locations

Identify in the field by its smoky transparency, hardness (it can scratch glass), and lack of cleavage. Commonly found in granitic pegmatites in locations like Brazil, USA (Colorado), and Switzerland.