mineral
Smoky Quartz
Silicon Dioxide (SiO2)
Color: Greyish-brown to black; Hardness: 7 on Mohs scale; Luster: Vitreous; Crystal system: Hexagonal; Cleavage: None (conchoidal fracture); Diaphaneity: Transparent to translucent.
- Hardness
- 7 on Mohs scale
- Color
- Greyish-brown to black
- Luster
- Vitreous
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Physical properties
Color: Greyish-brown to black; Hardness: 7 on Mohs scale; Luster: Vitreous; Crystal system: Hexagonal; Cleavage: None (conchoidal fracture); Diaphaneity: Transparent to translucent.
Formation & geological history
Forms in igneous and metamorphic rocks, particularly granite pegmatites. The dark color results from natural irradiation of aluminum-bearing quartz.
Uses & applications
Used in jewelry, decorative carvings, as a healing crystal in metaphysical practices, and for gemstone collection.
Geological facts
Smoky Quartz is the national gem of Scotland, where it is often referred to as 'Cairngorm' after the Cairngorm Mountains.
Field identification & locations
Identified in the field by its dark but transparent color and hardness (it will scratch glass). Commonly found in the Swiss Alps, Brazil, and the United States (Colorado).
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