Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (5) Citing Articles via Google Scholar Google Scholar Articles by Ishida, K. Articles by Hirowatari, F. Search for Related Content GeoRef GeoRef Citation

Shirozulite, KMn²⁺₃ (Si₃Al)O₁₀(OH)₂, a new manganese-dominant trioctahedral mica: Description and crystal structure

¹ Department of Evolution of the Earth and the Environment, Graduate School of Social and Cultural Studies, Kyushu University, 4-2-1 Ropponmatsu, Chuo-ku, Fukuoka 810-8560, Japan
² Department of Geological Sciences, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
³ 2734-1-1 Fukuma, Fukuoka 811-3213, Japan

Correspondence: ^* E-mail:kiyota{at}rc.kyushu-u.ac.jp

Shirozulite is a new Mn-dominant trioctahedral mica from the Taguchi mine, Aichi Prefecture, Japan. The mineral occurs in tephroite-rhodochrosite ores in contact with a Ba-bearing, K-feldspar vein. Shirozulite formed during regional low-P/T metamorphism and, thereafter, suffered thermal metamorphism from a local granodiorite. Grains of shirozulite are up to 0.5 mm across and have a typical micaceous habit. Color: dark reddish brown. Cleavage: (001), perfect. Optical properties: biaxial negative, 2V_x = very small. Strongly pleochroic: X = pale yellow, Y = Z = pale brown, absorption X <Y Z. Refractive indices: n = 1.592(2), n_ß n = 1.635(2). The structural formula is (K_0.90Ba_0.09) (Mn²⁺_1.53Mg_0.94Fe²⁺_0.20Ti_0.04Al_0.29) (Si_2.54 Al_1.46) O₁₀ [(OH)_1.97F_0.03], and the end-member composition is KMn²⁺₃AlSi₃O₁₀(OH)₂. Density: obs. = 3.20(3) g/cm³ by pycnometer, calc.= 3.14(2) g/cm³. Shirozulite is monoclinic, C2/m, 1M polytype, a = 5.3791(7), b = 9.319(1), c = 10.2918(9) Å, ß = 100.186(9)°, V = 507.8(1) ų. The six strongest lines in the powder X-ray diffraction pattern are as follows: d (Å), l (%), (hkl): 10.16, 100, (001); 2.654, 96, (31); 3.386, 51, (003); 1.556, 48, (13); 2.467, 46, (32); 2.202, 36, (33). The crystal structure has been refined to an R value of 4.1% based on 663 observed reflections collected with MoK X-radiation from a single crystal. The mean bond lengths, tetrahedral rotation, and octahedral flattening angles are as follows:<T-O> = 1.668,<M1-O> = 2.118,<M2-O> = 2.103,<K-O> (inner) = 2.995, and <K-O>(outer) = 3.376 Å, = 8.36°, _M1 = 58.5°, _M2 = 58.2°. The apparent element distribution coefficient analyses among coexisting manganese or manganoan silicate minerals indicate that the trioctahedral mica structure cannot contain larger amounts of Mn²⁺ relative to Mg and Fe²⁺ than in olivine, pyroxenoid, and garnet.

This article has been cited by other articles:

				A. Baumgartner, C. Butterhof, S. Koch, R. Mariychuk, and J. Breu MELT SYNTHESIS AND CHARACTERIZATION OF SYNTHETIC Mn-RICH TAINIOLITE Clays and Clay Minerals, April 1, 2009; 57(2): 271 - 277. [Abstract] [Full Text] [PDF]

				G. Tischendorf, H.-J. Forster, B. Gottesmann, and M. Rieder True and brittle micas: composition and solid-solution series Mineralogical Magazine, June 1, 2007; 71(3): 285 - 320. [Abstract] [Full Text] [PDF]

				P. Comodi, P. Fumagalli, S. Nazzareni, and P.F. Zanazzi The 10 A phase: Crystal structure from single-crystal X-ray data American Mineralogist, May 1, 2005; 90(5-6): 1012 - 1016. [Abstract] [Full Text] [PDF]

				J. A. Mandarino NEW MINERALS Can Mineral, August 1, 2004; 42(4): 1241 - 1260. [Full Text] [PDF]