<報文>東北地方産ケイ酸マンガン鉱の鉱物学的研究(第25報) : 岩手県肘葛鉱山産含マンガン緑閃石について

概要

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Green-colored manganoan actinolite from the contact metamorphosed bedded manganese ore deposits of the Hijikuzu mine occurs as lenticular aggregates of the prismatic crystals up to 2.5×1.5 mm in size, in rhodonite essential mass at Daiju and No. 5 drifts, and the minerals is closely assosiated with the yellow-brown spessartine. On the basis of 24 (O, OH, F), the chemical analyses of the materials for Daiju and No. 5 drifts yield the following empirical formulas : (Na_<0.06>K_<0.02>)_<0.08>(Na_<0.15>Ca_<1.65>Mn_<0.20>)_<2.00>(Mg_<2.61>Fe^<2+>_<1.60>Mn_<0.57>Al_<0.17>Fe^<3+>_<0.05>)_<5.00>(Si_<7.64>Al_<0.36>)_<8.00>O_<21.79>(OH_<1.99>F_<0.22>)_<2.21> for the Daiju drift material and (Na_<0.10>K_<0.02>)_<0.12>(Na_<0.20> Ca_<1.51>Mn_<0.29>)_<2.00>(Mg_<1.96>Fe^<2+>_<1.70>Mn_<0.84>Al_<0.33>Fe^<3+>_<0.16>Ti_<0.01>)_<5.00>(Si_<7.64>Al_<0.36>)_<8.00>O_<22.02>(OH_<1.56>F_<0.42>)_<1.98> for the No. 5 drift material. Variation in refractive indices and unit cell parameters with tremolite-actinolite-ferroactinolite series are presented graphically in variation diagrams versus Fe^<2+>/Fe^<2+>+Mg ratio. In all the composition ranges, a_0,b_0 and cell volume show an appreciable and systematic variation with composition, whereas c_0 and β vary little. In the natural minerals, the substitution of fluorine ion for hydroxyl causes the cell constant a_0 to decrease significantly.
東北大学の論文
1979-09-22