mineral

Smoky Quartz

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on the Mohs scale. Color: Brown to nearly black, translucent to opaque. Luster: Vitreous (glassy). Crystal Structure: Trigonal. Cleavage: None, conchoidal fracture. Specific Gravity: 2.65.

Hardness: 7 on the Mohs scale
Color: Brown to nearly black, translucent to opaque
Luster: Vitreous (glassy)

Identified July 29, 2026More mineral →

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Physical properties

Formation & geological history

Forms in igneous, metamorphic, and sedimentary environments. Its smoky color is caused by free silicon formed from natural irradiation of silicon dioxide over geological time.

Uses & applications

Used in jewelry, ornamental carvings, crystal healing, and formerly in optical instruments.

Geological facts

Smoky quartz is the national gemstone of Scotland, where it has a long history in traditional jewelry and Highland dress.

Field identification & locations

Identified by its characteristic brown color, conchoidal fracture, and hardness of 7. It is found globally, with notable deposits in Brazil, the United States, Switzerland, and Madagascar.