DICT.TW Dictionary Taiwan

 co·run·dum /kəˈrʌndəm/
 剛玉,金剛砂

 co·run·dum /kəˈrəndəm/ 名詞
 剛玉,剛沙,金剛沙,剛石

 Co·run·dum n.; pl. Corundums  [Also corindon.]  Min. The mineral alumina (Al2O3), as found native in a crystalline state.  Transparent varieties are used as gemstones, including sapphire, which is the fine blue variety; the oriental ruby, or red sapphire; the oriental amethyst, or purple sapphire; and adamantine spar, the hair-brown variety. It is the hardest substance found native, next to the diamond.
 Note: ☞ The name corundum is sometimes restricted to the non-transparent or coarser kinds. Emery is a dark-colored granular variety, usually admixed with magnetic iron ore.
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 corundum
      n : very hard mineral used as an abrasive [syn: corundom]