- a common mineral, aluminum oxide, Al2O3, 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
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for corundum
To polish diamonds they make use of the powder of adamantine spar, or the corundum stone.
Pliny says, corundum was used in the form of a splinter fixed in an iron style.
The stones have been rubbed into shape apparently by corundum.
The color of corundum is usually brown, but it varies greatly.Geology
William J. Miller
There are indications of sapphires and other forms of 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: Al 2 O 3 . Crystal structure: hexagonal (rhombohedral)
C18: from Tamil kuruntam; related to Sanskrit kuruvinda ruby
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
- 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.
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