mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Translucent to opaque brownish-grey to black; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Color: Translucent to opaque brownish-grey to black
Luster: Vitreous (glassy)

Identified January 1, 2026More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed in igneous and metamorphic rocks, particularly pegmatites and hydrothermal veins. The smoky color results from natural irradiation of aluminum-containing rock crystal during its geological history, which may span millions of years.

Uses & applications

Used widely in lapidary work and jewelry such as rings, pendants, and faceted gemstones. It is also a popular collector's mineral and is occasionally used in making oscillators for electronics if the specimen is of high purity.

Geological facts

Dark, nearly opaque specimens of smoky quartz are specifically referred to as 'Morion'. In Scotland, a variety found in the Cairngorm Mountains is known as Cairngorm stone and is the national gemstone of Scotland.

Field identification & locations

Identify in the field by its characteristic vitreous luster, lack of cleavage, and its ability to scratch glass (hardness 7). It is commonly found in mountainous regions such as the Alps, Brazil, and Colorado. Collectors should look for its glass-like fracture and transparency when held against light.