Cat's eye

From CAMEO
Jump to: navigation, search
Cat's Eye

Description

A semiprecious gemstone composed of quartz that contains a band of parallel fibers. When cut and polished as a cabochon, the band produces an opalescent light reflection that appears to move across the convex polished surface of the stone as it is rotated. This effect is called chatoyancy. Cat's eyes are usually a pale yellow or greenish color. A dark golden yellow cat's eye from South Africa is known as a tiger's eye or African cat's eye. It is a quartz stone with oriented fibers of crocicolite. True cat's eye is a variety of quartz, but other stones can also show this effect, such as chrysoberyl (oriental cat's eye), chalcedony, tourmaline, scapolite, cordierite, orthoclase, albite, willimanite and beryl. Corundum has an imperfect chatoyancy which produces a star effect rather than a line.

Polished tiger's eye cabochon

Synonyms and Related Terms

cat's-eye; tiger's eye; tiger eye; tigereye; quartz; cymophane; Tigerauge (Deut.); œil de tigre (Fr.); olho de tigre (Port.); tijgeroog (Ned.)

Other Properties

Trigonal crystal system. Low birefringence. Low thermal expansion.

Fracture = conchoidal. Luster = vitreous to greasy. Streak = white.

Mohs Hardness 7.0
Density 2.65

Additional Information

Mineralogy Database: Quartz

Comparisons

Properties of Gemstones


Sources Checked for Data in Record

  • Encyclopedia Britannica, http://www.britannica.com Comment: "cat's-eye" Encyclopædia Britannica. [Accessed September 19, 2003].
  • C.W.Chesterman, K.E.Lowe, Audubon Society Field Guide to North American Rocks and Minerals, Alfred A. Knopf, New York, 1979
  • Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976
  • Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997
  • The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998
  • Thomas Gregory, The Condensed Chemical Dictionary, Reinhold Publishing, New York, 3rd ed., 1942