mineral

Smoky Quartz

Silicon Dioxide (SiO2)

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

Identified April 22, 2026More mineral →

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Physical properties

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

Formation & geological history

Formed in igneous or metamorphic rocks (especially pegmatites). The smoky color is caused by natural irradiation of aluminum impurities within the quartz crystal over millions of years.

Uses & applications

Used in jewelry (gemstones), ornamental carvings, crystal healing collections, and historically for some of the first sunglasses in China.

Geological facts

Smoky quartz is the national gem of Scotland, where it is known as 'Cairngorm'. The dark color can vary depending on the amount of radiation the stone was exposed to during its formation.

Field identification & locations

Identify in the field by its hardness (scratches glass), glassy luster, and translucent to transparent 'smoky' appearance. Often found in riverbeds or near granite outcrops in places like the Alps, Brazil, and the USA.