mineral

Smoky Quartz

SiO2 (Silicon Dioxide with aluminum impurities)

Hardness: 7 on the Mohs scale. Color: Brown to black, smoky gray. Luster: Vitreous/glassy. Crystal System: Hexagonal/Trigonal. Cleavage: None (conchoidal fracture). Specific Gravity: 2.65.

Hardness: 7 on the Mohs scale
Color: Brown to black, smoky gray
Luster: Vitreous/glassy

Identified March 8, 2026More mineral →

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Physical properties

Hardness: 7 on the Mohs scale. Color: Brown to black, smoky gray. Luster: Vitreous/glassy. Crystal System: Hexagonal/Trigonal. Cleavage: None (conchoidal fracture). Specific Gravity: 2.65.

Formation & geological history

Formed in pegmatites and igneous rocks. The smoky color is caused by natural irradiation of aluminum-bearing quartz over millions of years within the Earth's crust.

Uses & applications

Used in jewelry (gemstones), ornamental carvings, and by collectors. Also historically used in early sunglasses in China and for metaphysical purposes.

Geological facts

Smoky quartz is the national gem of Scotland, where it is known as 'Cairngorm.' Large, well-formed crystals can grow to several hundred pounds in specialized geological pockets.

Field identification & locations

Identify by its translucent brown-to-gray color and its ability to scratch glass. Commonly found in Brazil, the Swiss Alps, Colorado (USA), and Scotland.

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