mineral

Smoky Quartz (Tumbled)

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: translucent grayish-brown; Luster: vitreous (glassy); Crystal structure: Hexagonal (trigonal); Cleavage: none (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 on Mohs scale
Color: translucent grayish-brown
Luster: vitreous (glassy)

Identified July 7, 2026More mineral →

Explore Smoky Quartz (Tumbled) in the encyclopedia →

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: translucent grayish-brown; Luster: vitreous (glassy); Crystal structure: Hexagonal (trigonal); Cleavage: none (conchoidal fracture); Specific gravity: 2.65

Formation & geological history

Formed in igneous and metamorphic rocks, particularly pegmatites and hydrothermal veins. The smoky color is caused by natural irradiation of aluminum impurities within the crystal lattice.

Uses & applications

Used in jewelry, decorative carvings, lapidary arts, and electronic components for its piezoelectric properties. It is also highly popular among mineral collectors.

Geological facts

Smoky quartz is the national gem of Scotland, where it is known as 'Cairngorm'. In ancient China, thin slices of smoky quartz were used to make the world's first sunglasses to protect the eyes from glare.

Field identification & locations

Identify by its translucent brown-to-black color and ability to scratch glass. Found globally, with notable deposits in Brazil, Switzerland, and the United States (Colorado). Field identification relies on hardness and lacks of cleavage.