mineral

Smoky Quartz

Silicon dioxide with aluminum impurities (SiO2)

Hardness: 7 on Mohs scale; Color: Varying shades of translucent brown to gray to black; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Color: Varying shades of translucent brown to gray to black
Luster: Vitreous (glassy)

Identified March 16, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous or metamorphic environments, particularly in pegmatites or hydrothermal veins. The brown color is the result of natural irradiation of trace aluminum impurities within the crystal lattice over millions of years.

Uses & applications

Commonly used in jewelry (faceting, beads, and cabochons), decorative carvings, and as a popular specimen for mineral collectors. Some industrial use in glassmaking or oscillator crystals, though usually synthetic quartz is preferred for those applications.

Geological facts

Smoky quartz is the national gem of Scotland, where it is known as Cairngorm. One of the few brown gemstones that is naturally occurring, it was used in China as early as the 12th century to make primitive sunglasses.

Field identification & locations

Identify in the field by its hardness (will scratch glass), lack of cleavage, and translucent brown 'smoke-like' color. It is commonly found in mountainous regions such as the Swiss Alps, Brazil, and the Pikes Peak region of Colorado.

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