mineral
Smoky Quartz
Silicon Dioxide (SiO2)
Hardness: 7 on Mohs scale; Color: Grey, brown, to black; Luster: Vitreous; Crystal Structure: Hexagonal (trigonal); Cleavage: Indistinct/Conchoidal fracture; Specific Gravity: 2.65.
- Hardness
- 7 on Mohs scale
- Color
- Grey, brown, to black
- Luster
- Vitreous
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Physical properties
Hardness: 7 on Mohs scale; Color: Grey, brown, to black; Luster: Vitreous; Crystal Structure: Hexagonal (trigonal); Cleavage: Indistinct/Conchoidal fracture; Specific Gravity: 2.65.
Formation & geological history
Formed in igneous or metamorphic rocks like granite or gneiss. The smoky color is caused by natural irradiation of aluminum-bearing quartz over geological time.
Uses & applications
Used in jewelry (faceted stones, beads), electronics (piezoelectric properties), and widely collected by mineral enthusiasts.
Geological facts
The dark color is the result of free silicon formed from silicon dioxide by natural irradiation. If heated to about 300-400 degrees Celsius, it can lose its smoky color.
Field identification & locations
Identify in the field by its hexagonal crystal habit, lack of cleavage, and translucent 'smoke' color. Commonly found in pegmatite veins and alpine fissures globally, especially in Brazil and the USA.
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Mineral/Rock
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Green Apatite on Albite
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