Topaz

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Description

An aluminum silicate mineral used as a semiprecious gemstone. Topaz is usually yellow but may also be colorless, blue, brown, or pink. The transparent to translucent stone occurs most often in rocks of the granite and rhyolite type. Some sources of topaz are the Ural Mountains, Ilmen Mountains, Sri Lanka, Germany (Saxony), Norway, Sweden, Siberia, Scotland, Japan (Takayama, Tanokamiyama), Brazil (Minas Gerais), Mexico, and the U.S. (New England, Texas, Utah, Colorado, California). In the Middle Ages, all yellow stones were called topaz. In 1750, it was noted that yellow Brazilian topaz would turn red when heated and these were sold as Brazilian rubies.

Topaz

Synonyms and Related Terms

hyacinth (dark orange); Brazilian ruby; Topas (Deut.); topacio (Esp.); topaze (Fr.); topaas (Ned.); topázio (Port.)

Raman

TopazRS.jpg

Raman

Topazitaly1.jpg


Other Properties

Orthorhombic system with mostly prismatic crystals. Perfect cleavage in one direction.

Fracture = subconchoidal and uneven. Luster = vitreous. Streak = colorless to white.

Yellow topaz turns a soft red when heated.

Fluorescence: may show yellowish color under long UV.

Composition Al2SiO4(F,OH)2
Mohs Hardness 8
Density 3.4-3.6
Refractive Index 1.61; 1.61; 1.63

Additional Information

Mineralogy Database: Topaz

Comparisons

Properties of Common Gemstones


Additional Images


Sources Checked for Data in Record

  • Jack Odgen, Jewellery of the Ancient World, Rizzoli International Publications Inc., New York City, 1982
  • R.F.Symmes, T.T.Harding, Paul Taylor, Rocks, Fossils and Gems, DK Publishing, Inc., New York City, 1997
  • A.Lucas, J.R.Harris, Ancient Egyptian Materials and Industries, Edward Arnold Publishers Ltd., London, 4th edition, 1962
  • Encyclopedia Britannica, http://www.britannica.com Comment: "topaz" Encyclopædia Britannica [Accessed December 4, 2001]. (color photo)(tech info)
  • C.W.Chesterman, K.E.Lowe, Audubon Society Field Guide to North American Rocks and Minerals, Alfred A. Knopf, New York, 1979
  • G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 646
  • 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
  • CRC Handbook of Chemistry and Physics, Robert Weast (ed.), CRC Press, Boca Raton, Florida, v. 61, 1980 Comment: density=3.5-3.6