mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 Mohs; Color: Brown to blackish-brown to smoky gray; Luster: Vitreous; Crystal structure: Trigonal/Hexagonal; Cleavage: Indistinct; Specific Gravity: 2.65

Hardness: 7 Mohs
Color: Brown to blackish-brown to smoky gray
Luster: Vitreous

Identified June 7, 2026More mineral →

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Physical properties

Hardness: 7 Mohs; Color: Brown to blackish-brown to smoky gray; Luster: Vitreous; Crystal structure: Trigonal/Hexagonal; Cleavage: Indistinct; Specific Gravity: 2.65

Formation & geological history

Forms in igneous rocks like granites and pegmatites, as well as metamorphic rocks. The smoky color is caused by natural irradiation of aluminum-bearing quartz over millions of years.

Uses & applications

Used in jewelry, decorative items, and by collectors. Historically used for sunglasses in 12th century China and for optical instruments.

Geological facts

The dark brown to gray coloring occurs when quartz contains trace amounts of aluminum and is subjected to natural radiation within the earth for long periods of time.

Field identification & locations

Identify by its characteristic smoky transparency and hardness (scratches glass). Common in Brazil, Madagascar, and the Swiss Alps. Look for its glassy luster and unique color gradient.