mineral
Smoky Quartz
Silicon Dioxide (SiO2)
Hardness: 7 on Mohs scale; Color: Grayish-brown to black; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (Trigonal); Cleavage: Indistinct; Specific Gravity: 2.65
- Hardness
- 7 on Mohs scale
- Color
- Grayish-brown to black
- Luster
- Vitreous (glassy)
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Physical properties
Hardness: 7 on Mohs scale; Color: Grayish-brown to black; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (Trigonal); Cleavage: Indistinct; Specific Gravity: 2.65
Formation & geological history
Formed in igneous or metamorphic rocks through the crystallization of magma or hydrothermal fluids. The color is caused by natural irradiation of aluminum-bearing quartz.
Uses & applications
Used frequently in jewelry (beads, faceted stones), as ornamental stones for collection, and in some optical or electronic applications.
Geological facts
Smoky quartz is the national gem of Scotland, where it is often referred to as 'Cairngorm' after the mountains where it was historically mined.
Field identification & locations
Identified in the field by its hardness (scratches glass), conchoidal fracture, and characteristic smoky translucency. Commonly found in granite pegmatites.
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