plagioclase

Noun. (rfc-def) (mineralogy) Any of a group of feldspar minerals that form a solid solution series from albite (sodium aluminum silicate) to anorthite (calcium aluminum silicate). The plagioclase feldspars are found in igneous, plutonic, and metamorphic rocks. They all have the triclinic-pinacoidal crystal habit, but only Albite commonly occurs in well crystallized specimens.

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This entry was last updated on RefTopia from its source on 3/20/2012.