mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Translucent to opaque brown-gray; Luster: Vitreous; Crystal structure: Trigonal/Hexagonal; Cleavage: None/Conchoidal fracture; Specific gravity: 2.65

Hardness: 7 on Mohs scale
Color: Translucent to opaque brown-gray
Luster: Vitreous

Identified April 17, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Translucent to opaque brown-gray; Luster: Vitreous; Crystal structure: Trigonal/Hexagonal; Cleavage: None/Conchoidal fracture; Specific gravity: 2.65

Formation & geological history

Forms in igneous and metamorphic rocks, particularly granite and pegmatites. The smoky color is created when natural radiation from surrounding rocks activates aluminum impurities within the quartz crystal structure.

Uses & applications

Used primarily in jewelry (as a gemstone), for decorative carvings, and as a popular collector's mineral specimen. Historically used in early 12th-century China for sunglasses.

Geological facts

Smoky Quartz is the national gem of Scotland, where it is known as Cairngorm. Some specimens can reach massive sizes weighing several hundred pounds.

Field identification & locations

Identify in the field by its distinct smoky transparency, lack of cleavage, and ability to scratch glass. It is common in alpine regions and mountains with granitic basement rocks.