| 概要 |
A new occurence of johannsenite has been found in manganese ore deposits at Teragōchi, Okayama Prefecture, Japan. The mineral occurs as a chief component of the massive manganess ore. Aggregates of bl...uish johannsenite crystals look quite similar to those of skarn hedenbergite. It has following chemical composition: SiO_2 48.02, TiO_2 tr., Al_2O_3 0.80, Fe_2O_3 0.30, FeO 3.20, MnO 27.53, MgO 0.48, CaO 19.10, Na_2O 0.25, K_2O 0.04, H_2O^+ 0.23, H_2O^- 0.00, total 99.95 wt. %. Silky green variety with following composition was also found: SiO_2 48.18, Al_2O_3 0.80, Fe_2O_3 1.00, FeO 4.82,MnO 26.29, MgO 0.47, CaO 18.79, Na_2O 0.20, K_2O 0.04, H_2O^+ 0.10, H_2O^- 0.00, total 100.69 wt. %. Optical properties for the blue johannsenite: α=1.707, β=1.720, γ=1.736,γ-α=0.029, 2V(+) 72°. Sp. gr. (blue variety)=3.54 (21℃). Unit cell dimensions obtained by X-ray powder method are: (blue variety) a_0=9.91_6Å, b_0=9.10_7Å, c_0=5.28_0Å, β=74°49’: (green variety) a_0=9.91_3Å, b_0=9.10_4Å, c_0=5.27_4Å,β=74°48’. Powder data and infrared spectra are also presented together with the heating effect of johannsenite.続きを見る
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Mendeley出力
15_01_p065