Reinvestigation of “betafite-pyrochlore” from Mitoko, Itoshima, Fukuoka Prefecture

Abstract

Okamoto (1941) reported the occurence of “betafite” from Mitoko, Itoshima, Fukuoka Prefecture. After the X-ray analysis by Kawai the mineral was thought to be “pyrochlore” (Okamoto, 1944; Nagashima & Nagashima, 1960). The specimen in the Okamoto Mineral Collection deposited in Kyushu University does not contain this lagre crystal of “betafite”. We reexamined using two specimens collected from the dumps of Mitoko pegmatite at 1985 by S. Iwano. The specimens were investigated by chemical analysis, X-ray diffraction analysis, and thermal analysis. The mineral was identified to be oxycalciobetafite.