<報文>東北地方産ケイ酸マンガン鉱の鉱物学的研究(第16報) : 岩手県茂市鉱山産含マンガングルーネ閃石について

概要

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Manganoan grunerite is found in a quartz vein up to 15 cm in width that cutting foot wall of banded chert at Urushizawa bedded manganese ore deposit of Moichi Mine, in chert of Permian age. The mineral occurs as asbestiform aggregates of very fine needle-like crystals about 10 cm in length and 1 μ in diameter. The color is white with silky luster. The specific gravity is 3.36 (meas.), 3.46 (calc.). Under the microscope, the amphibole is colorless and no pleochroism. The optical properties are as follows : α=1.664,β=1.679,γ=1.699,γ-α=0.035,2V_γ(calc.)=83° and c∧Z≒0°. When calculated according to the results of chemical analysis on the basis of 24 (O, OH), the following chemical formula is obtained : (Fe^<2+>_<2.79> Mn_<2.46> Mg_<1.43> Ca_<0.08>)_<7.03> (Si_<7.84> Al_<0.13> Fe^<3+>_<0.03>)_<8.00>O_<22.00>(OH_<1.84> O_<0.16>)_<2.00>. The X-ray powder data showed that the mineral is monoclinic with a_0=9.62,b_0=18.30,c_0=5.33 Å, β=102.1° and V=917.7 Å^3. The high temperature X-ray diffraction analysis and differential thermal analysis indicates that the mineral decomposes to jacobsite (a_0=8.44 Å), clinopyroxene and amorphous silica at about 1,000℃ in air.
東北大学の論文
1975-03-25