mineral
Smoky Quartz
Silicon Dioxide (SiO2)
Hardness: 7 on Mohs scale; Color: Smoky greyish-brown to black; Luster: Vitreous; Crystal system: Hexagonal (trigonal); Specific gravity: 2.65
- Hardness
- 7 on Mohs scale
- Color
- Smoky greyish-brown to black
- Luster
- Vitreous
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Physical properties
Hardness: 7 on Mohs scale; Color: Smoky greyish-brown to black; Luster: Vitreous; Crystal system: Hexagonal (trigonal); Specific gravity: 2.65
Formation & geological history
Forms in intrusive igneous rocks, pegmatites, and high-grade metamorphic rocks via hydrothermal fluids with natural exposure to radioactivity.
Uses & applications
Used extensively as a popular gemstone in jewelry, for decorative carving, and as lapidary and crystal healing specimens.
Geological facts
The brown to grey color of smoky quartz is created by natural irradiation of trace aluminum impurities within the silicon dioxide crystal structure.
Field identification & locations
Identified by its glass-like vitreous luster, hardness of 7 (scratches glass), conchoidal fracture, and characteristic translucent to transparent smoky grey color. Commonly found in Brazil, Madagascar, and the US.
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