mineral

Smoky Quartz

Smoky Quartz (Silicon Dioxide - SiO2)

Hardness: 7 (Mohs scale); Color: Brownish-grey, black, or translucent smoke-color; Luster: Vitreous (glassy); Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 (Mohs scale)
Color: Brownish-grey, black, or translucent smoke-color
Luster: Vitreous (glassy)

Identified March 20, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous or metamorphic rocks like granite. Its unique smoke color is caused by natural irradiation of aluminum impurities within the crystal lattice over millions of years of geological time.

Uses & applications

Used primarily in lapidary work for jewelry (beads, cabochons, faceted stones), ornamental carvings, and metaphysical collecting. Historically used for early sunglasses in 12th century China.

Geological facts

Smoky quartz is the national gem of Scotland, where it is known as 'Cairngorm' after the mountains where it was traditionally mined. Very dark, opaque varieties are sometimes called 'Morion'.

Field identification & locations

Identify in the field by its hardness (will scratch glass), translucent smoky transparency, and lack of cleavage. Commonly found globally in pegmatites and Alpine-type veins (Brazil, Switzerland, USA).