mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7.0 on Mohs scale; Color: Brown to black, smoky grey; Luster: Vitreous (glassy); Crystal Structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7
Color: Brown to black, smoky grey
Luster: Vitreous (glassy)

Identified March 9, 2026More mineral →

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Physical properties

Hardness: 7.0 on Mohs scale; Color: Brown to black, smoky grey; Luster: Vitreous (glassy); 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 color is caused by natural irradiation of aluminum-bearing quartz over millions of years.

Uses & applications

Used extensively in jewelry (pendants, rings), as decorative gemstones, in clock making (due to piezoelectric properties), and popular for metaphysical collecting.

Geological facts

Smoky quartz is the national gem of Scotland, where it is known as 'Cairngorm'. In the 12th century, it was used in China to create the first early versions of sunglasses.

Field identification & locations

Identify in the field by its transparency, smoky color, and lack of cleavage. Common locations include Brazil, Madagascar, the Swiss Alps, and Pikes Peak, Colorado. Collectors should look for deep coloration without internal fractures.