Corundum is a naturally occurring form of aluminum oxide that is found abundantly in Greece and Turkey and in New York State. It is a very hard mineral with a high melting point. It is relatively inert chemically and does not conduct an electrical current very well.
These properties make corundum highly desirable as a refractory (a substance capable of withstanding very high temperatures) and as an abrasive (a material used for cutting, grinding, and polishing other materials). One of the more mundane uses of corundum is in the preparation of toothpaste, where its abrasive properties help in keeping teeth clean and white.
In its granular form, corundum is known as emery. Many consumers are familiar with emery boards used for filing finger nails. Emery, like corundum, is also used in the manufacture of cutting, grinding, and polishing wheels.
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