Higher-silica zeolites in boninite rocks from Chichijima and Anijima, the Ogasawara Islands, Japan.

Abstract

Aggregate crystal zeolites are occurred in the boninite pillow lava and pillow breccia at Chichijima and Anijima, the Ogasawara Islands. At the localities in this study, heulandite/clinoptilolite, chabazite, stilbite, phillipsite and mordenite zeolites having the higher-silica composition are occurred co-existed with calcite, quartz/chalcedony and celadonite. Almost of the heulandite-like habit crystals sampled in the localities are identified as clinoptilolite in the base of IMA nomenclature.