Description
A very hard, naturally occurring mineral composed of aluminum oxide. Corundum is mined in Australia, South Africa, Zimbabwe, India, Russia, Rhodesia, Turkey, the United States and Canada (Ontario). The transparent to translucent stones are typically gray or brown with some deeply colored varieties. Transparent corundum stones have been used as gemstones since at least Hellenistic times. Rubies are transparent red corundum gems while transparent blue stones are called sapphires. Transparent yellow corundum is called Oriental topaz, the violet color is called Oriental amethyst and the green, Oriental emerald. Impure corundum, commonly called emery, also contains hematite, magnetite, silica and/or magnesia. Emery is used as an abrasive. Artificial corundum has been produced on a very small scale by the Verneuil process.
(Corundum should not be confused with Carborundum)
Synonyms and Related Terms
emery (black); adamantine spar; ruby (red); sapphire (blue); Oriental topaz (yellow); Oriental amethyst (lavender); Oriental emerald (green); korund (Dan., Ned., Pol.); Korund (Deut.); corindon (Esp., Fr., Port.);
| Al2O3 |
| 1302-74-5 |
| 8.9-9.0 |
| 3.96-4.05 |
| 1.761-1.769 |
Other Properties
Hexagonal crystal system with tabular, prismatic or pyramidal crystals.
Luster = vitreous to adamantine. Fracture = conchoidal. Streak = white
Fluorescence = orange to strong red. Heat treated stones may fluoresce green.
Natural stones contain microscopic mineral and fluid inclusions not seen in synthetic stones. Synthetic stones may have gas bubbles.
Hazards and Safety
Inhalation of dust may cause irritation. Fire retardant.
Additional Information
Mineralogy Database: Corundum
|
 |
|
 |
Images
8 total images
CorundumCorundum. Image credit: US Government. Uploaded to Wikipedia by Chris, Aug. 3, 2004. Image accessed Nov. 11, 2004 at Wikipedia |
corundum
Mineral collected from Chanthaburi, Thailand. Image credit: Raman Spectra Database of Minerals and Inorganic Materials (RASMIN) at http://www.aist.go.jp/RIODB/rasmin/E_index.htm |
Uncut ruby
Image of ruby crystal before faceting, length 0.8 inches (2 cm. The picture was made by placing crystal on the glass of flat bed scanner. Photographed by Adrian Pingstone in February 2003 and released to the public domain. (Accessed June 27, 2005 at www.wikipedia.com) |
Cut ruby
Photograph of cut ruby. (Accessed June 27, 2005 at www.wikipedia.com) |
Star sapphire
Photograph of star sapphire cabochon displaying six-ray asterism. Image credit: Mitchell Gore. (Accessed June 27, 2005 at www.wikipedia.com) |
Raman spectrum of corundum
Raman spectrum of mineral collected at 514.5 nm (Ar+ laser, 300 mW power). Credit: Raman Spectra Database of Minerals and Inorganic Materials (RASMIN) at http://www.aist.go.jp/RIODB/rasmin/E_index.htm |
Raman spectrum of corundum ruby
Raman spectrum of natural crystals in random orientation using a micro Raman instrument with a He-Ne laser (632.8 nm excitation wavelength). Credit: Physics Department of the University of Parma at http://www.fis.unipr.it./~bersani/raman/raman/spettri.htm |
Raman spectrum of corundum sapphire
Raman spectrum of natural crystals in random orientation using a micro Raman instrument with a He-Ne laser (632.8 nm excitation wavelength). Credit: Physics Department of the University of Parma at http://www.fis.unipr.it./~bersani/raman/raman/spettri.htm |
Authority
15 total authority records
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
Encyclopedia Britannica, http://www.britannica.com
comments: "corundum" Encyclopædia Britannica [Accessed December 11, 2001]
Website address 1
comments: http://www.geo.utexas.edu/courses/347k/redesign/gem_notes/Corundum/corundum_triple_frame.htm (Fluorescence information)
C.W.Chesterman, K.E.Lowe, Audubon Society Field Guide to North American Rocks and Minerals, Alfred A. Knopf, New York, 1979
Wikipedia, the free encyclopedia, at http://www.wikipedia.com
comments: http://en.wikipedia.org/wiki/Corundum (Accessed Sept. 7, 2005)
Robert Weast (ed.), CRC Handbook of Chemistry and Physics, v. 61, CRC Press, Boca Raton, Florida, 1980
comments: density=3.9-4.0
Ralph Mayer, The Artist's Handbook of Materials and Techniques, Viking Press, New York, 1981
Materials Handbook, G.S. Brady, McGraw-Hill Book Co., New York, 1971
comments: p. 244
Hawley's Condensed Chemical Dictionary, 10th ed., Richard S. Lewis, Van Nostrand Reinhold, New York, 1993
Michael McCann, Artist Beware, Watson-Guptill Publications, New York City, 1979
R.M.Organ, Design for Scientific Conservation of Antiquities, Smithsonian Institution, Washington DC, 1968
Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976
Webster's Encyclopedic Unabridged Dictionary of the English Language, Random House, Grammercy Book, New York, 1997
The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998
Last updated on: 7/6/2009 9:14:06 AM
|