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Related to corundum: Artificial Corundum
An extremely hard mineral, aluminum oxide, Al2O3, sometimes containing iron, magnesia, or silica, that occurs in gem varieties such as ruby and sapphire and in a common black, brown, or blue form used chiefly in abrasives.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
(Minerals) 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)
[C18: from Tamil kuruntam; related to Sanskrit kuruvinda ruby]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
a mineral, aluminum oxide, Al2O3, noted for its hardness: transparent varieties, as sapphire and ruby, are used as gems, other varieties as abrasives: often made synthetically.
[1720–30; < Tamil kuruntam; akin to Skt kuruvinda ruby]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
An extremely hard mineral composed mainly of aluminum oxide. It occurs in gem varieties such as ruby and sapphire and in a dark-colored variety that is used for polishing and scraping. Corundum is the mineral used to represent a hardness of 9 on the Mohs scale.
The American Heritage® Student Science Dictionary, Second Edition. Copyright © 2014 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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|Noun||1.||corundum - very hard mineral used as an abrasive|
mineral - solid homogeneous inorganic substances occurring in nature having a definite chemical composition
emery - a hard grey-black mineral consisting of corundum and either hematite or magnetite; used as an abrasive (especially as a coating on paper)
alumina, aluminium oxide, aluminum oxide - any of various forms of aluminum oxide occurring naturally as corundum
ruby - a transparent deep red variety of corundum; used as a gemstone and in lasers
sapphire - a precious transparent stone of rich blue corundum valued as a gemstone
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