Fig. 10b. An enlarged image of the rectangular frame of Fig. 10a when quartz plate is inserted. The scattered albite grains are separated into two groups (outlined by dashed lines). Each group has the same orientation as that of perthitic albite of the opposite K-feldspar. The phenomenon can be explained by superposed replacement of swapped albite rows occurring on the grain boundaries between two preexisting differently oriented primary K-feldspars, followed by nibble K-feldspathization. The replacing K-feldspar (K₁", K₂") is characterized by less perthitic albite only. The main part of K-feldspar (K₁, K₂) outside the albite grains may not be metasomatic in origin. The original border between two primary K-feldspars has been changed because of the growth intersection of the two replacing K-feldspars.