Smoky quartz

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Janus necklace
MFA# 2007.422
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.)

Smoky quartz

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

  • Jack Odgen, Jewellery of the Ancient World, Rizzoli International Publications Inc., New York City, 1982
  • C.W.Chesterman, K.E.Lowe, Audubon Society Field Guide to North American Rocks and Minerals, Alfred A. Knopf, New York, 1979
  • Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997

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