| 概要 |
Manganobarian muscovite, recently found in the manganese deposit of the Muramatsu mine, occurs in a braunite-rich manganese ore as a small veinlet, or as a coating on drusy cavities. It is rose-pink t...o light pink in colour, while under the microscope, practically colourless. n_X=1.566, n_Y=1.598, n_Z=1.602, n_Z-n_X=0.036; (-) 2V=36°, op. pl. ⊥010 The chemical formula is (K_<0.53>Na_<0.25>Ba<0.11>Ca_<0.09>)_<0.98>(Al_<1.48>Fe_<0.10>Mn_<0.20>Mg_<0.26>)_<2.04> (Si_<3.02>Al_<0.98>)_<4.00>O_<10.00> (OH)_ <2.00> The x-ray powder data confirm that polymorphic modification of this mineral agrees closely with that of the common 2-layer monoclinic structure proposed by HENDRICKS and JEFFERSON, giving the following monoclinic unit cell dimensions: a_0=5.25±0.02A, b_0=9.10±0.02A, c_0=19.90±0.03A, β=95°40’. Using these values, most of lattice spacings have been indexed. Thus, this mineral belongs to a mica of the muscovite type (heptaphyllite), with the 2-layer monoclinic structure (common or normal muscovite structure). But it differs from the common muscovite in containing unusually high amounts of barium and manganese.続きを見る
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Mendeley出力
05_04_p191