<報文>東北地方産ケイ酸マンガン鉱の鉱物学的研究(第5報) : 岩手県野田玉川鉱山産含マンガンカミントン閃石について

概要

論文の詳細を見る
Manganoan cummingtonite occurs as bandded or lenticular aggregates of long prismatic to bladed crystals up to 10×5×3mm in size, in rhodonite ore-body at + 50m level of Kirihata bedded manganese silicate deposit at Noda-Tamagawa Mine, in the highly metamorphosed older Cretaceous quartzites by the intrusion of granodiorite. The color is dark grayish green, specific gravity 3.15 and hardness 6.5. In transmitted light the pleochroism is very weak : X=colorless, Y=Z=pale yellow. The indices of refraction are : α=1.638,β=1.650,γ=1.662,γ-α=0.022 ; extinction angle cΛZ=22°. Optically biaxial negative ; 2Vα=88°. The unit cell dimensions are : a_0=9.63,b_0=18.11,c_0=5.29A, β=102.5° and a_0 sin β=9.40A ; and are very similar to those of cummingtonite-grunerite series. The chemical analysis gives the formula of (Na_<0.808>, Ca_<0.306>, K_<0.109>, Mg_<3.128>, Mn_<1.711>, Fe^<+2>_<0.499>, Fe^<+3>_<0.219>, Al_<0.191>, Ti_<0.038>)_<7.009> Si_<3.05> O_<21.704> (OH_<2.195>, F_<0.101>)_<2.296> as O+OH+F=24. The high-temperature X-ray diffraction and DTA indicate that the mineral breaks down to a mixture of clinopyroxene, jacobsite and glass at about 1,100℃.
東北大学の論文
1969-10-30