mineral
Smoky Quartz
Silicon Dioxide (SiO2)
Hardness: 7 on Mohs scale. Color: Brownish-grey to dark smoky brown. Luster: Vitreous to glossy when polished. Crystal Structure: Hexagonal (trigonal). Cleavage: None (conchoidal fracture). Specific Gravity: ~2.65.
- Hardness
- 7 on Mohs scale
- Color
- Brownish-grey to dark smoky brown
- Luster
- Vitreous to glossy when polished
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Physical properties
Hardness: 7 on Mohs scale. Color: Brownish-grey to dark smoky brown. Luster: Vitreous to glossy when polished. Crystal Structure: Hexagonal (trigonal). Cleavage: None (conchoidal fracture). Specific Gravity: ~2.65.
Formation & geological history
Forms in igneous and metamorphic rocks, such as granite and pegmatites, through natural irradiation of trace aluminum inclusions within the quartz matrix.
Uses & applications
Popular as a gemstone, polished cabochons, tumbled decorative stones, and specimens for mineral collectors.
Geological facts
Smoky quartz is the national gem of Scotland, where it has been mined for centuries in the Cairngorm Mountains. Its dark color ranges from translucent light grey-brown to almost opaque black (morion).
Field identification & locations
Identify by its vitreous luster, hardness of 7 (scratches glass), lack of cleavage, and translucent smoky brown coloration. Widely found in Brazil, Madagascar, the United States, and the Swiss Alps.
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