corundum

American  

[kuh-ruhn-duhm] / kəˈrʌn dəm /

noun

1. a common mineral, aluminum oxide, Al 2 O 3 , notable for its hardness: transparent varieties, as sapphire and ruby, are used as gems, other varieties as abrasives: often made synthetically.

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corundum British  

/ kəˈrʌndəm /

noun

1. 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)

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corundum Scientific  

/ kə-rŭn′dəm /

1. 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: Al ₂ O ₃ .

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Etymology

Origin of corundum

1720–30; < Tamil kuruntam; akin to Sanskrit kuruvinda ruby

Example Sentences

Corundum is important to the jewelry trade as ruby and sapphire.

From Textbooks • Feb. 14, 2019

Corundum, ko-run′dum, n. a mineral consisting of mere alumina, yet of great specific gravity—about four times that of water—and second in hardness only to the diamond.

From Chambers's Twentieth Century Dictionary (part 1 of 4: A-D) by Various

The Cranberry iron ores, the matchless Mica quarries and the Corundum deposits are all being made available to commerce, and will realize valuable returns for the capital employed upon them.

From School History of North Carolina : from 1584 to the present time by Moore, John W. (John Wheeler)

Corundum occurs also in Canada in an igneous rock, a nepheline-syenite, associated with Laurentian gneiss.

From Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 4 "Coquelin" to "Costume" by Various

Silex Corundum appeared to understand, and he indicated that the unfortunate man would receive attention.

From Through Space to Mars Or the Longest Journey on Record by Rockwood, Roy

Related Words

• gem
• jewel
• rhinestone