Thermal study on sameγtype ramsdellites

Abstract

Manganese dioxide mineral from the Iwasaki mine was examined by means of X-ray powder method and D. T. A, and the following results were obtained.
(1) The X-ray pattens are similar to Cole's γ-MnO₂I. Accordingly, the manganese mineral from the Iwasaki mine is defined to γ type ramsdellite.
(2) The D. T. A. curve of γ type ramsdellite consist of three peaks which are accompanied with exothermic peak at 370°C, and endothermic peaks at 600 and 980°C. The exothermic peak is phase change from γ-MnO₂I to β-MnO₂, two endothermic peak are reduction of β-Mn₂→Mn₂O₃ and Mn₂O₃→Mn₃O₄.
(3) A γ type ramsdellite is spreaded distribution in Japan, and some examples were given.