mineral

Smoky Quartz

Smoky Quartz (Silicon Dioxide, SiO2)

Hardness: 7 on Mohs scale; Color: Brownish-grey, black, or translucent smoke-color; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

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

Identified April 4, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous or metamorphic rocks like granite or pegmatites. The smoky color is caused by natural gamma radiation from surrounding minerals that induces color centers in the quartz lattice around aluminum impurities.

Uses & applications

Used primarily in lapidary work for jewelry (beads, cabochons, faceted gems), ornamental carvings, and as a popular specimen for mineral collectors.

Geological facts

Smoky quartz is the national gem of Scotland, where it is often referred to as 'Cairngorm.' Some of the darkest varieties are called 'Morion.' It was used for sunglasses in 12th century China.

Field identification & locations

Identify in the field by its hardness (scratches glass), lack of cleavage, and translucent brown color. Commonly found in mountainous regions like the Alps, Brazil, and the United States (Colorado).