Abstract
We report the mineralogical features of clay minerals from Nagatare Li pegmatite, and discuss the alteration processes. In Nagatare, Li pegmatite has veined structure, and clay-like minerals occur as red, pink, light blue and white masses or powders with Li minerals. Red clays were composed of K-Ca montmorillonite or cooketite with quartz. Pink clays were composed of K-beidellite, tosudite, cookeite and quartz. Light blue clays were composed of tosudite, cookeite and quartz. Tosudite was mixed layer minerals of
cookeite and Ca beidellite (or montmorillonite) layers. Various alteration reactions occurred with different formation temperature and composition of reaction fluid.
