noun \kə-ˈrən-dəm\

Definition of CORUNDUM

:  a very hard mineral that consists of aluminum oxide occurring in massive and crystalline forms, that can be synthesized, and that is used for gemstones (as ruby and sapphire) and as an abrasive

Origin of CORUNDUM

Tamil kuruntam; akin to Sanskrit kuruvinda ruby
First Known Use: 1804


noun \kə-ˈrən-dəm\   (Medical Dictionary)

Medical Definition of CORUNDUM

: a very hard mineral Al2O3 that consists of alumina occurring in massive form and as variously colored crystals which include the ruby and sapphire


noun    (Concise Encyclopedia)

Aluminum oxide mineral (AlO) that is, after diamond, the hardest known natural substance. Gem varieties are sapphire and ruby; mixtures with iron oxides and other minerals are called emery. Corundum is widespread in nature, although large deposits are rare. Rich deposits occur in India, Russia, Zimbabwe, and South Africa. In addition to being a precious gem, corundum is used as an abrasive for grinding optical glass and for polishing metals and has also been made into sandpapers and grinding wheels. For most industrial applications, however, it has been replaced by synthetic materials such as alumina; synthetic corundum is also manufactured.


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