mineral

Smoky Quartz

Smoky Quartz (SiO2)

Hardness: 7 on Mohs scale; Color: Grayish-brown to black; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Grayish-brown to black
Luster: Vitreous (glassy)

Identified April 21, 2026More mineral →

Identify your own rocks.

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

App Store Google Play

Physical properties

Hardness: 7 on Mohs scale; Color: Grayish-brown to black; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Formation & geological history

Formed in igneous or metamorphic environments, particularly pegmatites. The smoky color is caused by natural irradiation of aluminum-bearing quartz over millions of years.

Uses & applications

Used in gemstone jewelry, ornamental carvings, and as a popular specimen for mineral collectors. Historically used for ancient Chinese sunglasses.

Geological facts

Smoky quartz can range from nearly transparent to complete opacity. The dark black variety is known as 'Morion'. It is the national gem of Scotland, where it is often called 'Cairngorm'.

Field identification & locations

Identify by its glassy luster, lack of cleavage, and ability to scratch glass. Commonly found in granite mountains and vugs. Collectors should look for distinct crystal faces or the characteristic smoky translucence.