mineral
Smoky Quartz
Silicon Dioxide (SiO2)
Hardness: 7 on Mohs scale. Color: Translucent grayish-brown to dark smoky gray with iron oxide staining along fractures. Luster: Vitreous (glassy). Crystal structure: Trigonal. Cleavage: None (conchoidal fracture).
- Hardness
- 7 on Mohs scale
- Luster
- Vitreous (glassy)
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Physical properties
Hardness: 7 on Mohs scale. Color: Translucent grayish-brown to dark smoky gray with iron oxide staining along fractures. Luster: Vitreous (glassy). Crystal structure: Trigonal. Cleavage: None (conchoidal fracture).
Formation & geological history
Formed in igneous and metamorphic environments, commonly in pegmatites and hydrothermal veins. The smoky coloration is produced by natural underground radiation acting on trace aluminum impurities within the quartz crystal lattice.
Uses & applications
Used primarily in lapidary work, jewelry making, and as decorative mineral specimens for collectors.
Geological facts
Smoky quartz is the national gem of Scotland, where it has been mined for centuries in the Cairngorm Mountains and is traditionally called Cairngorm stone.
Field identification & locations
Identified by its hardness (scratches glass), glass-like glassy luster, conchoidal fracture, and brownish-translucent color. Commonly found worldwide in pegmatite deposits, granitic terrains, and stream gravels.
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