mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Brownish-grey to black; Luster: Vitreous; Crystal Structure: Hexagonal (Trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Color: Brownish-grey to black
Luster: Vitreous

Identified March 22, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Brownish-grey to black; Luster: Vitreous; Crystal Structure: Hexagonal (Trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Formed in igneous and metamorphic rocks, particularly pegmatites and hydrothermal veins. The brown color is caused by natural irradiation acting on aluminum impurities within the silica crystal lattice.

Uses & applications

Used in jewelry (gemstones), decorative carvings, and as a healing stone in metaphysical circles. In industry, high-quality quartz is used for electronics and optics.

Geological facts

Smoky quartz is the national gem of Scotland, where it is known as 'Cairngorm' after the mountain range where it was historically found. Unlike some minerals, its color can often be lightened by heat treatment.

Field identification & locations

Identify by its smoky translucence, lack of cleavage, and ability to scratch glass. Commonly found in Brazil, Madagascar, and the United States (Colorado). Collectors look for well-defined terminal faces and 'phantom' inclusions.