Smoky Quartz

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

Gemological information

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
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.

Lang Antiques
Lang Antiques