corundum(redirected from Corrundum)
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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.
(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]
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]
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.
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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