Definitions for oligoclaseˈɒl ɪ goʊˌkleɪs
Random House Webster's College Dictionary
ol•i•go•claseˈɒl ɪ goʊˌkleɪs(n.)
a plagioclase feldspar occurring in white, gray, greenish, or reddish crystals.
Origin of oligoclase:
any of a series of triclinic feldspars that form rocks
A plagioclase feldspar, the second member of the Albite-Anorthite solid solution series. Primarily found as small crystals in impure marble. Oligoclase contains a small amount of calcium substituting for some of the sodium in its formula. Oligoclase with reddish-golden inclusions found in Norway and Canada is called sunstone.