Figure F6. Photomicrograph illustrating cristobalite-clay alteration (colorless patches) of pale brown volcanic glass in a moderately altered volcanic rock from Site 1191. Note that microlitic plagioclase and magnetite (fine opaque spots) are apparently unaffected by the alteration (interval 193-1191A-2R-2, 103-106 cm, in plane-polarized light; field of view = 0.7 mm. Photomicrograph ID# 1191A_7; thin section 49).