corundum

co·run·dum  (k-rndm)

n.

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.

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[Tamil kuruntam.]

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corundum

Noun

a hard mineral used as an abrasive, and of which the ruby and white sapphire are precious forms [Tamil kuruntam]

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corundum  (k-rndm)

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.

Thesaurus

Noun

1.

corundum - very hard mineral used as an abrasive corundom 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