Fig. 8.-Plagioclase is partly nibbly replaced by K-feldspar

A---Cross polarized light. K ₃ single prime has nibbly replaced the rim of plagioclase Pl₁ on the basis of primary K-feldspar K₃.

B---Plus quartz plate. The relicts of plagioclase maintain the original orientation.

C---Cathodoluminescent image. K ₃ single prime has the similar tone as K₃ except less light blue.