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A white, gray, green, or yellow variety of plagioclase feldspar that contains approximately equal proportions of sodium and calcium and occurs in igneous rocks of intermediate silica content, such as andesite and diorite.
(Minerals) a feldspar mineral of the plagioclase series consisting of an aluminium silicate of sodium and calcium. Formula: NaAlSi3O8.CaAl2Si2O8
[C19: from the Andes (where it is found) + -ine1]