mineral

Smoky Quartz

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 (Mohs scale), Color: Brownish grey to black, Luster: Vitreous (glassy), Crystal system: Hexagonal (trigonal), Cleavage: None (conchoidal fracture), Specific gravity: 2.65

Identified July 13, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale), Color: Brownish grey to black, Luster: Vitreous (glassy), Crystal system: Hexagonal (trigonal), Cleavage: None (conchoidal fracture), Specific gravity: 2.65

Formation & geological history

Forms in igneous and metamorphic rocks, particularly granite and pegmatites. The smoky color is caused by natural irradiation of aluminum impurities within the crystal lattice.

Uses & applications

Used primarily in jewelry as a gemstone, for ornamental carvings, and as a popular collector's mineral. Historically used for making early sunglasses in China.

Geological facts

The national gemstone of Scotland is a variety of smoky quartz known as Cairngorm. Large crystals weighing over 100 pounds are not uncommon in pegmatite deposits.

Field identification & locations

Identify by its translucence, conchoidal (shell-like) fracture, and the fact it can scratch glass but not topaz. Commonly found in mountainous regions like the Alps, Brazil, and the United States (Colorado).