mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Brownish-grey to black; Luster: Vitreous; Crystal structure: Trigonal; Cleavage: None/Conchoidal fracture; Specific gravity: 2.65

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

Identified July 15, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Brownish-grey to black; Luster: Vitreous; Crystal structure: Trigonal; Cleavage: None/Conchoidal fracture; Specific gravity: 2.65

Formation & geological history

Forms in igneous and metamorphic rocks, particularly pegmatites and hydrothermal veins. The color is caused by natural irradiation of aluminum-bearing quartz.

Uses & applications

Used in jewelry, decorative carvings, and as a popular specimen for collectors. In industry, quartz is used for its piezoelectric properties and in glass making.

Geological facts

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

Field identification & locations

Identify by its characteristic smoky translucence and hardness (it will scratch glass). Commonly found in granite-rich mountainous regions worldwide such as the Swiss Alps and Brazil.