mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 Mohs; Color: Brownish-grey to black (translucent); Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: Indistinct; Specific Gravity: 2.65

Hardness: 7 Mohs
Color: Brownish-grey to black (translucent)
Luster: Vitreous (glassy)

Identified May 24, 2026More mineral →

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Physical properties

Hardness: 7 Mohs; Color: Brownish-grey to black (translucent); Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: Indistinct; Specific Gravity: 2.65

Formation & geological history

Forms in igneous and metamorphic rocks, particularly pegmatites and hydrothermal veins. The brown color is caused by natural irradiation of aluminum-bearing quartz over geological time.

Uses & applications

Used in jewelry, decorative carvings, and as a popular collector's specimen. Historically used for early sunglasses in China.

Geological facts

Smoky quartz is the national gem of Scotland, where it is known as 'Cairngorm'. Very dark/opaque varieties are sometimes called 'Morion'.

Field identification & locations

Identify by its transparency and characteristic smoky brown color. Found globally in granite-rich mountainous regions like the Alps, Brazil, and the United States (Colorado).