tri·chro·ism /ˌtraɪˈkroˌɪzəm/ 名詞
  三色性,三色型
  Tri·chro·ism n.  Min. The quality possessed by some crystals of presenting different colors in three different directions.
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  trichroism
       n : pleochroism of a crystal so that it exhibits three different
           colors when viewed from three different directions