Podrobnosti záznamu

Název
    Description and crystal structure of vajdakite, (( Mo 6+ O2)2(H2O)2As3+2O5).H2O - A new mineral from Jáchymov, Czech Republic
Údaj o odpovědnosti
    Petr Ondruš, Roman Skála, Ivana Císařová, František Veselovský, Jiří Čejka
Autor
    Císařová, Ivana
    Čejka, Jiří
    Frýda, Jiří
    Ondruš, Petr
    Skála, Roman
    Veselovský, František
Jazyk
    anglicky
Zdrojový dokument - seriál
    American mineralogist
Svazek/č.
    Vol. 87, no. 7
Strany
    p. 983-990
Rok
    2002
Poznámky
    7 obr., 1 fot., 12 tab., 17 s.bibl.
    il.
    Zkr. název ser.: Amer. Mineralogist
Předmětová skupina
    analýza termická
    arzenidy
    chemismus minerálů
    difrakce rentgenová
    krystalová struktura
    minerály supergenní
    molybden
    nový minerál
    rudy U
    spektrometrie IR
Geografické jméno
    ČR-Čechy
    Jáchymov (Karlovy Vary)
Klíčové slovo
    6+
    Crystal
    Czech
    Description
    Jáchymov
    Mineral
    Mo
    New
    O2)2(H2O)2As3+2O5).H2O
    Republic
    Structure
    Vajdakite
Abstrakt (anglicky)
   Vajdakite, a new mineral from Jáchymov, NW Bohemia, Czech Republic, forms minute acicular, gray-green crystals associated with arsenolite, scorodite, parascorodite, kaňkite, annabergite, köttigite, pyrite, marcasite, nickelskutterudite, and löllingite. Microprobe analysis gave (in wt%): As=27.72, Mo=35.39, O=36.66, total=99.77. The simplified chemical formula is [(Mo6+O2)2(H2O)2As3+2O5] . H2O. The mineral is monoclinic, P21/c, a=7.0515(6), b=12.0908(9), c=12.2190(14) A, =101.268(9)°, V=1021.7(2) A3, Z=4, Dmeans=3.50(2) g/cm3, and D calc=3.509 g/cm3. The strongest lines in the powder X-ray diffraction pattern d(I)(hkl) are: 6.046 (100)(020), 3.324 (59)(023), 6.915 (26)(100), 2.264 (19)(310), 3.457 (16)(200), 2.624 (15)(230), and 3.819 (10)(031). Vajdakite is otically posititive, with X II b and Z c=12°, elongation is positive. Its birefrigence is 0.28, ith 2Vcalc=35.1°, n=1.757(2), n=1.778(2), and n=2.04(1). The pleochroic scheme is X-Y=light greenish gray, and Z=yellowish gray.
   Crystal size varies between 0.1 to 0.5 mm. TG curve and IR spectra show that vajdakite contains two distinct types of ater molecules. The crystal structure was solved by direct methods (MoK radiation) and refined using 1787 unique reflections to R=0.0455, Rw=0.1143. There are double chains built up by two individual chains with a sequence -O-As-O-Mo- interconnected by oxegen atoms from two triangular AsO3 groups and two structurally nonequivalent MoO5(H2O) octahedra. The two vertex-sharing, triangular AsO3 groups form as (As2O5)4- diarsenite group. The first type of water molecule is not included in the coordination, but the second one is in octahedral coordination around Mo. The water molecules are linked by a complicated net of interlayer and intralayer hydrogen bonds
Přispěvatel
    Česká geologická služba
Kód přispěvatele
    ČGS (UNM)
Zdrojový formát
    U
Datum vložení
    21. 8. 2007
Datum importu
    8. 8. 2012