mineral
Smoky Quartz
Silicon Dioxide (SiO2)
Hardness: 7 on Mohs scale; Color: Translucent grayish-brown to smoky black; Luster: Vitreous (glassy); Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65
- Hardness
- 7 on Mohs scale
- Color
- Translucent grayish-brown to smoky black
- Luster
- Vitreous (glassy)
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Physical properties
Hardness: 7 on Mohs scale; Color: Translucent grayish-brown to smoky black; Luster: Vitreous (glassy); Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65
Formation & geological history
Formed in igneous or metamorphic rocks through the natural irradiation of aluminum-bearing quartz over long geological periods. Commonly found in pegmatite veins and hydrothermal veins.
Uses & applications
Used primarily as a gemstone in jewelry, in crystal healing practices, and as decorative collector specimens. High-purity quartz is also used in electronics.
Geological facts
The dark color is caused by free silicon formed from silicon dioxide by natural irradiation. In ancient China, smoky quartz was used to make the first 'sunglasses' to hide the expressions of judges in courts.
Field identification & locations
Identify in the field by its hardness (will scratch glass), glassy luster, and characteristic smoky translucency. Found globally in granitic terrains.
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Other mineral specimens
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Sandstone with Mineral Veining or Crust
Sedimentary Sandstone (mostly SiO2 with Fe2O3 tinting)
sedimentary
Schist
Schist
Metamorphic
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Nephrite Jade
Nephrite
Mineral/Rock