Primary ore minerals of bedded manganese ore deposits in Japan

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1. Primary minerals of bedded manganese ore deposits The manganese ore deposits studied in this term are as follows : Kamisagaya mine, Nagasaki mine, and Mikubo mine in the Chichibu Teraine ; Inuyama in the Mino Teraine ; Yatani mine, Ashitani mine, and Jido mine in the Tamba Teraine. As a result, the primary minerals of bedded manganese ore deposits have been clarified to be rhodochrosite, bementite, and hausmannite. The ores show commonly a striped texture like to lamina and rarely a spheroidal texture by rhodochrosite. The primary manganese ore minerals from the Wafanzi mine on the Proterozoic plateau in China are rhodochrosite and manganese dioxide minerals, and show often a spheroidal texture. The primary minerals from the big ore deposits on plateau in the world are also similar to those of the Wafanzi mine.2. Synthesis of manganese ore texture A primary texture of manganese ore is represented by striped and spheroidal textures. The textures have been easily synthesized by the gel method. Experiments have been performed as to rhodochrosite and manganese oxide mineral. Rhodochrosite has been synthesized in gel containing carbon dioxide ion by diffusion of manganese ion, and vice versa. As a result, the spherulite with a radial texture and a striped texture composed of spherulites have been obtained. Manganese oxide minerals have been also synthesized in gel containing sodium hydroxide by diffusion of manganese ion. The same texture as those of rhodochrosite have been obtained. The spheroidal particle however shows a concentric texture. In conclusion, the present results suggest that the primary texture of manganese ore is formed not only by sedimentary process but also by diffusion process.