mineral

Smoky Quartz

Smoky Quartz (Silicon Dioxide - SiO2)

Hardness: 7 on Mohs scale; Color: Translucent gray to brownish-black; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: Indistinct/None; Specific Gravity: 2.65.

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

Identified March 23, 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: Translucent gray to brownish-black; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: Indistinct/None; Specific Gravity: 2.65.

Formation & geological history

Formed in igneous or metamorphic environments, primarily within pegmatites and hydrothermal veins. The color is caused by natural irradiation of aluminum-bearing silicon dioxide during the cooling of the Earth's crust over millions of years.

Uses & applications

Extensively used as a gemstone in jewelry (rings, pendants), as decorative carvings, in crystal healing practices, and as a prized collector's mineral specimen.

Geological facts

Smoky Quartz is the national gem of Scotland, where it is known as 'Cairngorm.' Some of the darkest varieties from the Swiss Alps are called 'Morion' and appear almost opaque black.

Field identification & locations

Identify in the field by its distinct smoky color, conchoidal fracture (curved, glass-like breaks), and its ability to scratch glass but not topaz. Commonly found in Brazil, Madagascar, Switzerland, and the United States (Colorado).