Smoky Quartz

Smoky Quartz is a brownish black to greyish color variety of quartz. Cairngorm is the Scottish term for smoky quartz

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Gemological Information for Smoky Quartz

Color: Brown to Black or Smoky Grey
Crystal Structure Hexagonal (trigonal)
Refractive Index: 1.544 to 1.553
Durability: Good
Hardness: 7
Family: Quartz
Similar Stones: Andalusite, Tourmaline, Idocrase
Treatments: Quench Crackle, Irradiation, Heat Treatment and Coating or Backing
Country of Origin: Brazil, Scotland, India, Madagascar, Mexico, Srilanka, South Africa, Russia

Smoky Quartz Care

Ultrasonic Cleaning: Usually Safe
Steam Cleaning: Risky
Warm Soapy Water: Safe
Chemical Attack: Soluble in Hydrofluoric Acid and Ammonium Fluoride
Light Sensitivity: Usually Stable
Heat Sensitivity: May Fracture or Change Color

Sources

  • Gem Reference Guide, Los Angeles: Gemological Institute of America, 1988. Pp. 187-190.
  • Newman, Harold. An Illustrated Dictionary of Jewelry, New York: Thames and Hudson, 1981. Pp. 283.
  • Schumann, Walter. Gemstones of the World, New York: Sterling Publishing, Co., 1977. Pp. 116.