Calcian serandite in a magnesioriebeckite-quartz schist from the Mitsuishi district, Hidaka Province, Hokkaido

Abstract

Calcian serandite was found in a magnesioriebeckite-quartz schist from Mitsuishi, Hidaka Province, Hokkaido. The schist is composed of magnesioriebeckite, epidote, calcian serandite, albite, aegirine and quartz. Chemical composition and physical properties of the mineral are presented together with the results of chemical analyses of magnesioriebeckite, pectolite and the host whole rock. The calcian serandite seems to be formed as a primary metamorphic mineral judging from its mode of occurrence. It is assumed that the appearance or disappearance of the mineral in the crystalline schist depends on the chemical composition of the host rock under the condition of the epidote-glaucophane schist facies. This is the first finding of calcian serandite from metamorphic rocks.