Smoky Quartz

Physical Properties

Hardness: 7 (Mohs); Color: translucent brownish-grey to smoky black; Luster: Vitreous; Crystal system: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Formation & Geological History

Formed in igneous or metamorphic rocks, specifically pegmatites and hydrothermal veins. The smoky color is caused by natural irradiation of aluminum-bearing quartz over millions of years.

Uses & Applications

Used primarily in jewelry as a gemstone, for ornamental carvings, and by crystal collectors for aesthetic and metaphysical purposes.

Geological Facts

The color center is created when radiation knocks an electron off an aluminum atom that has substituted for a silicon atom in the quartz lattice. It was used for the first sunglasses in 12th century China.

Field Identification & Locations

Identify by its glass-like luster, lack of cleavage, and characteristic 'root beer' or smoky tint. Commonly found in Brazil, Colorado (USA), Switzerland, and Scotland (where it is known as Cairngorm).

Identified on: 4/13/2026

Mode: Standard