Manganoan winchite in a quartz schist from the Saruta-gawa area in the Sanbagawa metamorphic terrain, central Shikoku, Japan

Abstract

Manganoan winchite (up to 4.19 wt.% MnO) occurs as cores of zoned amphibole in a quartz schist from the Saruta-gawa area in the Sanbagawa metamorphic terrain, central Shikoku, Japan. The quartz schist consists of quartz, albite, amphibole, muscovite, garnet, chlorite, allanite, calcite, apatite, stilpnomelane, tourmaline, hematite and pyrite. The amphibole is euhedral to subhedral in form (up to 700 μm long). The core of the amphibole ranges in composition from barroisite through winchite to manganoan winchite. The amphibole is rimmed by alkali amphibole (mainly magnesioriebeckite) and winchite. Garnet in the quartz schist is rich in spessartine component (59-79%).