<報文>東北地方産ケイ酸マンガン鉱の鉱物学的研究(第23報) : 岩手県野田玉川鉱山産含マンガンリヒター閃石について

概要

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Manganoan richterite occurs as a single crystal up to 15×8 mm in size, and lenticular aggregates of granular crystals under about 5 mm across in the rhodonite essential mass with subordinate amounts of tephroite, manganoan mica and quartz at L 11 -S 400 of Misago bedded manganese ore deposits of the Noda-Tamagawa mine, in the highly metamorphosed Jurassic quartzite by the intrusion of the granitic body. The color is greenish black, luster vitreous, and specific gravity 3.12 (meas.) and 3.147 (calc.). In the thin section, it is weak pleochroic with X pale greenish yellow, Y≒Z yellow and optically biaxial negative with 2 V 65°(meas.). The extinction angle (Z∧c) is 17°. The unit cell parameters calculated from the X-ray powder pattern are a 9.91_3,b 18.07_8,c 5.30_8 A, β 104°12', V 922.2A^3 and Z-2. Chemical analysis leads to an empirical formula, (K_<0.37>Na_<0.29>)_<0.61> (Na_<1.25>Ca_<0.69>Mn_<0.06>)_<2.00> (Mg_<3.04>Mn_<1.31>Fe^<2+>_<0.17>Fe^<3+>_<0.44>Ti_<0.04>)_<5.00> (Si_<7.72>Al_<0.20>Fe^<3+>_<0.08>)_<8.00>O_<21.70> (OH_<2.21>F_<0.09>)_<2.30>, showing the material belongs to richterite of Leake's nomenclature. The differential thermal analysis indicates that the mineral decomposies into a mixture of clinopyroxene, jacobsite and roedderlite at about 1,070℃ in air.
東北大学の論文
1978-09-16