Autunite series from the Ningyo pass, Okayama prefecture

Abstract

Autunite, meta-autunite I and meta-autunite II are known as autunite seires until now. A uranium mineral had collected at the contact zone ningyo-toge granite and sedimentary rock, Ningyo-toge, Okayama prefecture. As a result of XRD analyzing, the uranium mineral, which had d₀₀₁=90.65 nm, was detected with autunite and meta-autunite I. Electoron microprobe analysis of the uranium mineral gave the empirical formula Ca(UO2)₂(PO₄)₂-6.5H₂O based on O =17. It was considered that the mineral is one of meta-autunite where have higher water content than meta-autunite I and II.