Figure F57. Photomicrographs showing plagioclase microlites variably replaced by colorless illite and dirty brown pyrophyllite. Note that the pyrophyllite shows white internal reflection under the reflected light (interval 193-1188F-11G-1, 138-141 cm, Unit 39, in (A) plane-polarized transmitted light and (B) reflected light; width of view = 0.7 mm. Photomicrograph ID# 1188F_31 and 1188F

Figure F57. Photomicrographs showing plagioclase microlites variably replaced by colorless illite and dirty brown pyrophyllite. Note that the pyrophyllite shows white internal reflection under the reflected light (interval 193-1188F-11G-1, 138-141 cm, Unit 39, in (A) plane-polarized transmitted light and (B) reflected light; width of view = 0.7 mm. Photomicrograph ID# 1188F_31 and 1188F_32; thin section 75).