Observations on oscillatory zoning, progressive zoning, and the lack of zoning in plagioclase feldspar of igneous and metamorphic rocks indicate a use in the interpretation of provenance of sedimentary rocks. Plagioclase in volcanic and hypabyssal rocks is characterized by oscillatory zoning, whereas this type of zoning is relatively rare in plutonic igneous and metamorphic rocks. The presence of zoned plagioclase, regardless of the type of zoning, is strongly indicative of an igneous rock.

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