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