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[kuh-ruhn-duh m] /kəˈrʌn dəm/
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 of corundum
1720-30; < Tamil kuruntam; akin to Sanskrit kuruvinda ruby Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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British Dictionary definitions for corundum


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

"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
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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