Fluor edenite from the Ishigamiyama lava dome of the Kimpo volcano, Kumamoto, southwest Japan

Abstract

Fluor edenfite was found in cavities of the Ishigamiyama lava dome building two pyroxene-hornblende-andesite in the Kimpo volcano, Kumamoto, southwest Japan. The fluor edenfite is associated with tridymites and magnetites in the cavities. This is the first description of volcanic fluor-amphibole, and its chemical analysis was made by combining microprobe, vacuum-heating method and Mössbauer spectroscopy. The Ishigamiyama fluor edenite has 1.47F, 0.13OH, 0.03Cl and 0.37O pfu in the O3 site, and thus, is characteristically poor in (OH). This edenite is the most F-rich one in edenites and edenitic hornblendes previously reported.