corundums

1 definition found

corundums - Collaborative International Dictionary of English v.0.48 :

  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]