MANGANPYROSMALITE FROM THE KYURAZAWA MINE, TOCHIGI PREFECTURE

抄録

Manganpyrosmalite (Mn, Fe)₈Si₆O₁₅(OH, Cl)₁₀ occurs abundantly as ore forming mineral at the Shinsanjin ore body of the Kyurazawa mine, Tochigi Prefecture, Japan. The first occurrence of pyrosmalite in Japan has been reported from another ore body of the same mine. The chemical analysis of the newly found manganpyrosmalite by J. Ito gave SiO₂ 35.43, FeO 9.57, MnO 42.01, MgO 1.14, Al₂O₃ 0.50, Cl 5.00, SO₃ 0.17, H₂O(±) 7.50, -O=Cl₂ -1.13, total 100.19%. Sp. gr. 3.12, hardness 41/2; ε=1.631, ω=1.667, ω-ε=0.036, uniaxial negative; lattice constants measured from the X-ray powder pattern are a₀=13.42Å, and c₀=7.159Å. The associated minerals are rhodonite, manganese amphibole, garnet, mangancalcite, quartz and small amounts of sulphide minerals. The chemical analysis of previously reported pyrosmalite from the Odaki ore body in this mine by H. Haramura came out as follows; SiO₂ 33.50, TiO₂ 0.08, Al₂O₃ 0.11, Fe₂O₃ 1.07, FeO 24.09, MnO 27.62, MgO 1.65, ZnO 0.04, CaO ?? 0.02, H₂O(-) 0.22, H₂O(+) 6.53, P₂O₅ ?? 0.02, Cl 5.63, -O=Cl₂ -1.27, total 99.31%. The correlation between the refractive indices and FeO contents of the minerals of friedelite-manganpyro-smalite-pyrosmalite series is given.