mineral

Smoky Quartz

Silicon Dioxide (SiO2) with natural radiation induced color centers

AI-generated identification · may be incorrect

Hardness: 7 (Mohs scale); Color: Grayish-brown to black; Luster: Vitreous; Crystal System: Trigonal (Hexagonal prisms); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

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

Identified June 9, 2026More mineral →

Explore Smoky Quartz 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 (Mohs scale); Color: Grayish-brown to black; Luster: Vitreous; Crystal System: Trigonal (Hexagonal prisms); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Formation & geological history

Formed in igneous or metamorphic rocks through the cooling of silica-rich solutions in veins or pockets. Its color results from natural gamma radiation and small amounts of aluminum impurities within the crystal lattice.

Uses & applications

Used primarily in jewelry as a gemstone, decorative carvings, and in metaphysical collecting. Industrially, quartz is used in oscillators for watches and electronics.

Geological facts

Smoky Quartz is the national gem of Scotland, where it is known as Cairngorm. Large crystals weighing hundreds of pounds have been found in Brazil.

Field identification & locations

Identify by its hardness (scratches glass), lack of cleavage, and translucent brown/gray smoky color. Commonly found in pegmatite dikes and granite pockets within mountain ranges like the Alps or the Rockies.