218527.fig.007a
(a)
218527.fig.007b
(b)
218527.fig.007c
(c)
218527.fig.007d
(d)
Figure 7: Photomicrographs showing the decreasing amount of plagioclase microlites and increasing amount of sericite content from Grades I to IV (crossed nicols, × 1 0 0 ((a), (b)), × 2 0 0 ((c), (d)); (Plj mic.: plagioclase microlite)). Fresh dacite consisting of a great amount of unweathered plagioclase microlites and trace amount of sericite (a), slightly weathered dacite showing a reduction in the amount of microlites and increase in the amount of slightly weathered sericite (b), moderately weathered dacite showing almost sericitized microlites (c), highly weathered dacite with completely sericitized microlites and replacement of these grains into groundmass (d).