mineral
Smoky Quartz
Silicon Dioxide (SiO2)
Hardness: 7 (Mohs scale); Color: Brownish-grey to black; Luster: Vitreous; Crystal system: Trigonal; Cleavage: None/Conchoidal fracture; Specific gravity: 2.65
- Hardness
- 7 (Mohs scale)
- Color
- Brownish-grey to black
- Luster
- Vitreous
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Physical properties
Hardness: 7 (Mohs scale); Color: Brownish-grey to black; Luster: Vitreous; Crystal system: Trigonal; Cleavage: None/Conchoidal fracture; Specific gravity: 2.65
Formation & geological history
Forms through the natural irradiation of aluminum-bearing quartz in granitic pegmatites or hydrothermal veins. Often found in pockets within igneous rocks.
Uses & applications
Used extensively in jewelry, ornamental carvings, and as a popular specimen for crystal healing and mineral collecting.
Geological facts
The dark color is caused by free silicon formed from silicon dioxide by natural irradiation. If heated to about 300-400 degrees Celsius, it will lose its color.
Field identification & locations
Identify by its transparency combined with charcoal or tea-like smoky hues. Found globally, with notable deposits in the Swiss Alps, Brazil, and the United States (Colorado).
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