mineral

Smoky Quartz

Silicon Dioxide (SiO2)

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

Hardness: 7 on Mohs scale
Color: Brownish-gray to near black
Luster: Vitreous (glassy)

Identified July 9, 2026More mineral →

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Physical properties

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

Formation & geological history

Formed in igneous and metamorphic rocks, particularly granite pegmatites. The color is caused by natural radiation from surrounding rocks acting on aluminum impurities within the quartz after crystallization.

Uses & applications

Used in jewelry (cut as gemstones), ornamental carvings, and for metaphysical purposes. Occasionally used in optical instruments and electronics, though synthetic quartz is preferred for those.

Geological facts

Smoky quartz was used in 12th-century China to make the first sunglasses. The darkest, almost black variety is known as 'Morion'. It is the national gem of Scotland.

Field identification & locations

Identify in the field by its distinct smoky color, lack of cleavage, and ability to scratch glass. Found globally in granitic terrains, notably in Switzerland, Brazil, and the USA (Colorado).