mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 on the Mohs scale; Color: transluculent grey, brown, to nearly black; Luster: Vitreous; Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 on the Mohs scale
Color: transluculent grey, brown, to nearly black
Luster: Vitreous

Identified March 29, 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

Forms 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 over millions of years.

Uses & applications

Used frequently in jewelry (faceted stones and beads), ornamental carvings, and by collectors. In industry, quartz is used in glass making and electronics, though high-clarity natural smoky quartz is more aesthetic in value.

Geological facts

Smoky quartz is the national gem of Scotland, where it is known as 'Cairngorm' after the mountain range where it was historically mined. It can vary from 'Morion' (nearly black) to 'Cairngorm' (yellow-brown).

Field identification & locations

Identify in the field by its hardness (will scratch glass), lack of cleavage, and smoky translucent color. It is commonly found in Brazil, Madagascar, the Swiss Alps, and the United States (Colorado and New Hampshire).