mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale. Color: Brownish-grey, smoky grey, to translucent black. Luster: Vitreous (glassy). Crystal system: Hexagonal (trigonal). Cleavage: None. Fracture: Conchoidal. Specific gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Brownish-grey, smoky grey, to translucent black
Luster: Vitreous (glassy)

Identified July 24, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous and metamorphic rocks, such as pegmatites, granites, and alpine-type veins. The distinct smoky color results from natural irradiation of aluminum-bearing quartz over long geological time periods.

Uses & applications

Used in jewelry, wire-wrapping, lapidary art, and metaphysical/crystal collecting. Larger pieces are sometimes used for ornamental carvings.

Geological facts

Smoky Quartz is the national gem of Scotland, where it has been mined for centuries in the Cairngorm Mountains and is traditionally called Cairngorm. Ancient Chinese jurists used flat panes of smoky quartz as early dark sunglasses to hide their facial expressions during trials.

Field identification & locations

Identified by its transparency combined with a smoky brown to dark grey color, glass-like luster, and hardness (scratches glass, cannot be scratched by a steel knife). Commonly found in Brazil, Madagascar, the US (Colorado, Maine), and the Alps.