mineral
Smoky Quartz
Silicon Dioxide (SiO2)
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)
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Physical properties
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.
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.
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