Fig. 16. More advanced stage of microcline (light gray; orthoclase ?) replacing core of plagioclase crystal (cream white). Irregular islands of remnant unreplaced plagioclase occur in the microcline, and these islands are in optical parallel continuity with the outside larger plagioclase crystal. (Biotite-hornblende quartz monzonite; sample HQ 98-1, Fig. 1).