mineral

Smoky Quartz

Smoky Quartz (Silicon Dioxide, SiO2)

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

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

Identified March 29, 2026More mineral →

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Physical properties

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

Formation & geological history

Formed in igneous or metamorphic rocks like pegmatites and granites. The smoky color results from natural irradiation of aluminum impurities within the crystal lattice over millions of years.

Uses & applications

Commonly used in jewelry (as shown in the electroplated specimen), metaphysical collecting, and historically for early sunglasses in 12th century China.

Geological facts

Black, opaque smoky quartz is often called 'Morion' in Europe. In Scotland, large smoky quartz crystals found in the Cairngorm Mountains are known as 'Cairngorm' stones.

Field identification & locations

Identify in the field by its crystal habit (six-sided prisms with pyramids) and the fact it scratches glass easily but cannot be scratched by a steel knife. Common in Brazil, Switzerland, and the USA (Colorado).