Record details

Title
    Crystal structure, cation ordering and polytypic character of diaphorite, Pb2Ag3Sb3S8, a PbS-based structure
Statement of responsibility
    Thomas Armbruster, Emil Makovický, Peter Berlepsch, Jiří Sejkora
Author
    Armbruster, Thomas
    Berlepsch, Peter
    Makovický, Emil
    Sejkora, Jiří, 1968-
Language
    anglicky
Source title - serial
    European journal of mineralogy
Vol./nr.
    Vol. 15, no. 1
Pages
    p. 137-146
Year
    2003
Notes
    5 obr., 7 tab., 16 bibl.
    il.
    Zkr. název ser.: Eur. J. Mineral.
Subject group
    antimon
    krystalová struktura
    olovo
    polytypie
    stříbro
    stupeň uspořádanosti
    substituce
    sulfosoli
Geographical name
    ČR-Čechy
    Příbram
Keyword
    Cation
    Character
    Crystal
    Diaphorite
    Ordering
    Pb2Ag3Sb3S8
    PbS-based
    Polytypic
    Structure
Abstract (in english)
   he crystal structure of diaphorite, Pb2Ag3Sb3S8, from hydrothermal veins at Příbram in central Bohemia (Czech Republic) was solved and refined from X-ray data of a crystal twinned by pseudo-merohedry. Diaphorite is rnonoclinic, space group P2l/c, a = 17.852(4), b = 5.887(1), c = 15.809(3) A and |3 = beta116.17(3)° ,Z=4,ró = 6.06 g/cm3. The structure can be derived from the one of galena, PbS, by the substitution Ag+ + Sb3+ <- 2 Pb2+. In addition to eight S, three Sb, two Ag, and one Pb positions, the average structure exhibits also two mixed (Pb2+, Ag+) sites (Ml, M2). The different coordination requirements for Pb2+ and Ag+ make a complete miscibility between these ions rather unlikely. The observed structure is a family or superposition structure and four possible, maximally Pb2+, Ag+ ordered structures can be derived with space-group symmetries (la): PI, (Ib) and (2a): P21ln, and (2b): P2,.
   The structures (la) and (2b) have the same cell dimensions as the family structure whereas structures (Ib) and (2a) have a doubled a periodicity compared to the family structure. In addition, each of the above space groups gives rise to two different configurational variants depending on the spatial relation of homoionic occupied M1 and M2 sites
Contributor
    Česká geologická služba
Contributor code
    ČGS (UNM)
Source format
    U
Entered date
    15. 8. 2007
Import date
    8. 8. 2012