Ore deposit of the Sanpo mine buried between green tuff breccia and pebble bearing sandstone belong to the Kunnui-Formation of Neogene Tertiary is manganese ore deposit of bedded form called the Pirika type.
Most of the Pirika type deposits occurred in the Yakumo-Formation or between the Yakumo- and Kunnui-Formations are commonly constituted with the ore min srals of manganese oxide such as pyrolusite, cryptomelane, nsutite, manganite and so on. Though ore deposit of the Sanpo mine is one of the Pirika type deposits, it differs from the others on several points such as stratigraphical horizon of mineralization, and properties of country rocks and paragenesis of ore minerals. Especially, piedmontite-braunite associations in dense ore, and montmorillonitepiedmontite assemblage in the hanging wall-rock, are very interesting.
Thus we concluded that the bedded manganese ore deposits of the mine might be caused by epigenetic condition.
View full abstract