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corundum

[kuh-ruhn-duh m] /kəˈrʌn dəm/
noun
1.
a common mineral, aluminum oxide, Al 2 O 3 , notable for its hardness: transparent varieties, as sapphire and ruby, are used as gems, other varieties as abrasives: often made synthetically.
Origin
1720-1730
1720-30; < Tamil kuruntam; akin to Sanskrit kuruvinda ruby
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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Examples from the web for corundum
  • Rubies, valued as precious gems, are the mineral corundum in its red form.
  • Rubies are formed of a mineral called corundum, comprised of aluminum oxide.
  • No doubt large corundum crystals and pieces of corundum are found each year.
  • The cordierite occurs along with sillimanite, corundum, and kyanite.
  • Since corundum has not been reported from here, it is not a true emery deposit.
  • Abrasive corundum is synthetically manufactured from bauxite.
British Dictionary definitions for corundum

corundum

/kəˈrʌndəm/
noun
1.
a white, grey, blue, green, red, yellow, or brown mineral, found in metamorphosed shales and limestones, in veins, and in some igneous rocks. It is used as an abrasive and as gemstone; the red variety is ruby, the blue is sapphire. Composition: aluminium oxide. Formula: Al2O3. Crystal structure: hexagonal (rhombohedral)
Word Origin
C18: from Tamil kuruntam; related to Sanskrit kuruvinda ruby
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for corundum
n.

"very hard mineral," 1728, from Anglo-Indian, from Tamil kurundam "ruby sapphire" (Sanskrit kuruvinda), of unknown origin.

Online Etymology Dictionary, © 2010 Douglas Harper
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corundum in Science
corundum
  (kə-rŭn'dəm)   
An extremely hard mineral occurring in many colors, either as shapeless grains or as rhombohedral crystals. It also occurs in gem varieties such as ruby and sapphire and in a dark-colored variety that is used for polishing and scraping. Corundum is found in igneous and carbonate rocks. Chemical formula: Al2O3.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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