著者

南部 松夫 谷田 勝俊

出版者

Japan Association of Mineralogical Sciences

雑誌

岩石鉱物鉱床学会誌 (ISSN:00214825)

巻号頁・発行日

vol.65, no.1, pp.1-15, 1971-01-05 (Released:2008-08-07)

参考文献数

14

被引用文献数

6 7

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Chemical analysis of takanelite a new manganese dioxide mincral from Nomura mine, Ehime Prefecture gave; MnO270.39, MnO 13.06, MgO 0.22, CaO 2.66, BaO none, Na2O 0.05, K2O 0.05, Fe2O3 1.34, Al2O3 1.70, TiO2 trace, SiO2 3.61, H2O(+) 4.92, H2O(-) 2.22, sum 100.22%. After deducting Al2O3, SiO2, Fe2O3, H2O(-) and a part of H2O(+) (present as halloysite, goethite and quartz), it corresponds to (Mn+20.89 Ca0.23 Mg0.03)1.15 Mn+43.94 O9.00 1.3H2O as O=9, or ideally (Mn+2, Ca) Mn4+4O9•nH2O with Mn+2〉Ca and n=1.3. This is the Mn+2 analogue of rancieite, (Ca, Mn+2) Mn+44O9•nH2O with Ca〉Mn+2 and n=3. Electron microprobe analyses of five different grains, using analysed rancieite, nsutite and todorokite as standards, gave Mn 60.5-62.3 and Ca 2.0-2.4, and Fe, Al and Si were not detected. These results validate the above analysis and deduction of impurities. Analyses of some other materials suggest the possible existence of a continuous solid solution series between rancieite and this mineral. X-ray powder data are very similar to those of rancieite by Sorem and Gunn (1967) and by Richmond, Fleischer and Mrose (1969), and includes the strongest lines 7.57 (100) (1010), 4.43 (10b) (0002, 1120), 3.76 (25) (2020), 2.462 (15) (1123), 2.349 (20) (2023), 2.065 (10) (2133), 1.754 (7) (2243, 1015), 1.420 (17) (5052, 4260, 1126). The indexing is based on the hexagonal cell with a0=8.68Å, c0=9.00Å, Z=3. Colour steel gray to black, luster submetalic to dull, streak brownish black, sp. gr. 3.41 (measured on impure material); 3.78 (calculated). Cleavage not observed. Vickers' hardness (load 100g) 480kg/mm2(average). In reflected light, yellowish gray, reflection pleochroism weak with yellowish white to yellowish light gray, anisotropism moderate with polarization colour of yellowish gray to light brownish gray. Etch reactions: HCI (conc.), HNO3(conc.) and H2SO4 (conc.) tarnish slightly grayish brown, H2SO4 (conc. ) +H2O2 (20%) and SnCl2 (sat.) quickly stain black. The mineral occurs as irregular-shaped nodules, 1-15cm across, composed of a microscopic intergorwth with a small quantity of braunite, halloysite, goethite and quartz, in the oxidation zone of the braunite-rhodochrosite-caryopilite bedded deposit at the Nomura mine, Ehime Prefecture, Japan, in low grade metamorphosed cherts of Permian age. The name is for the late Dr. Katsutoshi Takane (1899-1945), the former Professor of Mineralogy, Tohoku University, Sendai, Japan. Type material is preserved at Tohoku University. The mineral and name were approved before publication by the Commission on New Meinerals and Mineral Names, IMA.