Corundums

1 definition found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  Corundum \Co*run"dum\ (k[-o]*r[u^]n"d[u^]m), n.; pl. {Corundums}
     (k[-o]*r[u^]n"d[u^]mz). [Also corindon.] [From Hind. kurand
     corundum stone.] (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.
     [1913 Webster +PJC]
  
     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.
           [1913 Webster]