Podrobnosti záznamu

Název
    Rossmanite, (Li Al2) Al6 (Si6 O18) (BO3)3 (OH)3, a new alkali-deficient tourmaline: Description and crystal structure
Údaj o odpovědnosti
    Julie B. Selway, Milan Novák, Frank C. Hawthorne, Petr Černý, Luisa Ottolini, T. Kurtis Kyser
Autor
    Černý, Petr
    Hawthorne, Frank C.
    Kyser, T. Kurtis
    Novák, Milan, 1952-
    Ottolini, Luisa
    Selway, Julie B.
Jazyk
    anglicky
Zdrojový dokument - seriál
    American mineralogist
Svazek/č.
    Vol. 83, no. 7-8
Strany
    p. 896-900
Rok
    1998
Poznámky
    1 obr., 6 tab., 2 s.bibl.
    Zkr. název ser.: Amer. Mineralogist
Předmětová skupina
    krystalová struktura
    moldanubikum strážecké
    nový minerál
    pegmatit
    turmalín
Geografické jméno
    ČR-Morava
    Rožná (Žďár nad Sázavou)
Klíčové slovo
    Al2
    Al6
    Alkali-deficient
    BO3)3
    Crystal
    Description
    Li
    New
    O18
    OH)3
    Rossmanite
    Si6
    Structure
    Tourmaline
Abstrakt (anglicky)
   Rossmanite is a new tourmaline species from near Rožná, western Moravia, Czech Republic. It forms pale pink columnar crystals about 25 mm long and 5 mm thick, elongated along c with striations parallel to c on the prism faces. It is brittle, H = 7, D mcas = 3.00 g/c3, D calc = 3.06 g/cm3. In plane-polarized light, it is colorless. Rossmanite is uniaxial negative, = 1.645(1), = 1.624(1), triagonal, space group R3m, in the hexagonal setting a = 15.770(2), c = 7.085(1)A, V=1525.8(4)A3, Z = 3. The strongest six X-ray diffraction lines in the powder pattern are at d = 3.950 A with I = 100% for (hkl) = (220); 2.552 A, 93%, (051); 1.898 A, 72%, (342); 4.181 A, 58%, (211); 2.924 A, 56%, (122); and 3.434 A, 53%, (012). Analysis by a combination of electron microprobe, SIMS, H-line extraction, and crystal-structure refinement gave SiO2 38.10 wt%, Al2 O3 44.60, Na2 O 1.43, Li2 O = 1.13, B2 O3 = 10.88, H2 O = 3.70, F = 0.20, O = F 0.08, sum = 99.96 wt%, Fe, Mg, Ca, Mn, Ti, F, K not detected.
   The formula unit (31 anions) is x (0.57 Na 0.43) y (li 0.71 Al 2.17)z Al6 (Si 5.92 O18) (B 2.92 O9) (OH)3.83 F 0.10 O 0.07, with the ideal end-member formula (Li Al2) Al6 (Si6 O18) (BO3)3 (OH)4; thus rossmanite can be derived from elbaite [Na(al1.5 Li1.5) (Si6 O18) (BO3)3 (OH)4] by the substitution x 2 + yAl - xNa2 + yLi, where = vacancy. The crystal structure of rossmanite was refined to an R index of 1.7% using 1094 observed (5 ) reflections collected with MoK X-radiation from a single crystal. The structure refinement confirmed the low occupancy of the X site and the presence of Li at the Y site. There is considerable positional disorder at the O1 and O2 sites induced by the local variations is bond-valence distribution associated with -Na disorder at X and Li-Al disorder at Y
Přispěvatel
    Česká geologická služba
Kód přispěvatele
    ČGS (UNM)
Zdrojový formát
    U
Datum vložení
    18. 2. 2008
Datum importu
    8. 8. 2012