Abstract
Morphological and chemical studies on high quartz-like trigonal dipyramids from voids in a medium-grained massive augelite-trolleite-andalusite-quartz rock from pyrophyllite deposit of the Hinomaru-Nako mine, Abu-cho, Yamaguchi Prefecture, western Japan, suggest they are trolleite-augelite pseudomorphs after berlinite. The occurrence indicates that the formation of berlinite was of hydrothermal origin and took place after the precipitation of pyrite, or under lower temperature and pressure conditions. Also, the existence of trolleite as a pseudomorph in voids is interpreted as proof that its formation does not always require high-pressure metamorphic conditions.
