Smoky quartz
Description
A transparent dark gray or brown Quartz, also called cairngorm. Smoky quartz is found in Switzerland, Scotland (Mt. Cairngorm), Russia, Iran, Brazil, Sri Lanka and the U.S.(Colorado, California). It is sometimes used as a Gemstone. Most early uses of the stone date from Hellenistic times or later; one earlier example was found in Iran c 3250 BCE (Odgen 1982).
Synonyms and Related Terms
smokey quartz; cairngorm; Cairngorm stone; Rauchquarz (Deut.); quartz fumé (Fr.); quartzo fumado (Port.); rookkwarts (Ned.)
Physical and Chemical Properties
Trigonal crystal system. Low birefringence. Low thermal expansion.
Fracture = conchoidal. Luster = vitreous to greasy. Streak = white.
Heat-treatment can bleach the stone and may turn it yellow.
| Composition | SiO2 |
|---|---|
| Mohs Hardness | 7.0 |
| Density | 2.65 |
| Refractive Index | 1.55 |
Comparisons
Properties of Common Gemstones
Resources and Citations
- Mineralogy Database: Quartz
- Jack Odgen, Jewellery of the Ancient World, Rizzoli International Publications Inc., New York City, 1982
- Encyclopedia Britannica, http://www.britannica.com Comment: "smoky quartz." Accessed: 21 Jan. 2005 .
- C.W.Chesterman, K.E.Lowe, Audubon Society Field Guide to North American Rocks and Minerals, Alfred A. Knopf, New York, 1979
- Wikipedia: http://en.wikipedia.org/wiki/Smoky_quartz (Accessed Sept. 14, 2005)
- Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997