mineral

Smoky Quartz

Smoky Quartz (Silicon Dioxide, SiO2)

Hardness: 7 on Mohs scale. Color: 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: Brownish grey to black
Luster: Vitreous (glassy)

Identified May 10, 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: Brownish grey to black. Luster: Vitreous (glassy). Crystal Structure: Hexagonal (trigonal). Cleavage: None (conchoidal fracture). Specific Gravity: 2.65.

Formation & geological history

Forms in igneous and metamorphic rocks, especially in granitic pegmatites. The dark color is caused by natural gamma irradiation of clear quartz containing trace amounts of aluminum.

Uses & applications

Used in jewelry, decorative items, and as a popular specimen for collectors. Historically used for making sunglasses in 12th century China.

Geological facts

The dark variety is often called 'Morion'. It is the national gem of Scotland, where it is known as 'Cairngorm' after the mountains where it is found.

Field identification & locations

Identify by its translucent brownish color and hexagonal crystal habit. Found globally, with notable deposits in Brazil, Switzerland, and the United States (Colorado).