<報文>東北地方産ケイ酸マンガン鉱の鉱物学的研究(第26報) : 岩手県野田玉川鉱山産含マンガン含鉄サポー石について

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Manganese and iron rich saponite occur as aggregates of fine particles filling the fracture zone of the fault which cuts the rhodonite-tephroite-pyrochroite ore body at L1N95 of Misago bedded manganese ore deposits of the Noda-Tamagawa mine, in the highly metamorphosed Jurassic quartzite by the intrusion of the granitic mass. They are black in color and very pale brownish in thin section. The basal reflection shfits form 15.3A to 17.0A from treatment with ethylen glycol, and the spacing of (06,33) is 1.535A. Thus the X-ray powder pattern of this type is very close to those of trioctahedral smectite. Chemical analysis gives : SiO_2 37.19,TiO_2 0.00,Al_2O_3 3.61,Fe_2O_3 8.14,FeO 0.00,MnO 11.62,MnO_2 2.58,MgO 8.51,CaO 2.00,Na_2O 0.53,K_2O 0.10. H_2O^+ 6.86,H_2O^- 18.53,total 99.67 wt.%. If the empirical formula is made through chemical analysis, the octahedral coordination is 5.41,which is between di- and trioctahecral smectite, and some amounts of Fe^<3+> must have the tetrahedral coordination. Then, it is postulated that all Fe^<3+> and Mn^<4+> were derived from Fe^<2+> and Mn^<2+> by natural oxidation, the following empirical formula was made by converting all Fe^<3+> into Fe^<2+> and Mn^<4+> into Mn^<2+> : {Na_<0.20> K_<0.03> (Ca/2)_<0.42>}_<0.65> (Mg_<2.47>Mn^<2+>_<2.27>Fe^<2+>_<1.19>Al_<0.08>)_<6.01> [Si_<7.25>Al_<0.75>]_<8.00>O_<20>(OH)_2・2.5H_2O. In this case, the number of ions having an octahedral coordination is 6.01,and this formula corresponds to that of manganese and iron rich saponite, in which 58% of Mg ion of usual saponite replaced by 38% of Mn^<2+> and 20% of Fe^<2+>. The mineral is a variety having more Mn^<2+> content than any examples ever known.
東北大学の論文
1980-03-06

<報文>東北地方産ケイ酸マンガン鉱の鉱物学的研究(第26報) : 岩手県野田玉川鉱山産含マンガン含鉄サポー石について

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