mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Grey to brownish-black; Luster: Vitreous (glassy); Crystal Structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Color: Grey to brownish-black
Luster: Vitreous (glassy)

Identified July 13, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Grey to brownish-black; Luster: Vitreous (glassy); Crystal Structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Forms in igneous rocks like granite and pegmatites, as well as metamorphic rocks. The dark color is produced when clear quartz is exposed to natural radiation from surrounding rocks over millions of years.

Uses & applications

Used widely as a gemstone in jewelry, for ornamental carvings, and in metaphysical practices. Historically used for making primitive sunglasses in China.

Geological facts

The color center is created by the presence of trace amounts of aluminum replacing silicon, which is then activated by gamma radiation. When heated to high temperatures, it can turn yellow or colorless.

Field identification & locations

Identify by its translucent to transparent smoky grey color, glassy luster, and characteristic conchoidal fracture (curved, shell-like breaks). Common in mountaineous regions globally.