Record details

Title
    Refinement of the crystal structure of zinnwaldite 2M1
Statement of responsibility
    Milan Rieder, Jiří Hybler, Lubomír Smrčok, Zdeněk Weiss
Author
    Hybler, Jiří
    Rieder, Milan
    Smrčok, Lubomír
    Weiss, Zdeněk
Language
    anglicky
Source title - serial
    European journal of mineralogy
Vol./nr.
    Vol. 8, no. 6
Pages
    p. 1241-1248
Year
    1996
Notes
    2 obr., 7 tab., 20 bibl.
    Zkr. název ser.: Eur. J. Mineral.
Subject group
    cinvaldit
    krystalová struktura
    polytypie
    slídy
Geographical name
    ČR-Čechy
    Krupka (Teplice)
Keyword
    2M1
    Crystal
    Refinement
    Structure
    Zinnwaldite
Abstract (in english)
   Crystal structure of zinnwaldite 2M1 was refined in the Cc space with R equal to 5.8and Rw 7.5Its octahedral sheet is hetero-octahed ral, with octahedra around M1 and M3 having the same mean cation-anion bond legth, whereas the third (around M2) has the mean bond significantly shorter. In terms of electrons, the cation ordering between M1 and M3 is less pronounced (16.2 e-vs 17.4 e-) than that between M1 (M3) and M2 (14.3 e-). Li and Fe2+ prefer M1 (M3) to M2, Al does the opposite. Thus, like zinnwaldite 1M (Guggenheim & Bailey, 1977), the 2M1 polytype is hetero-octahedral. This is the first two-layer hetero-octahedral mica polytype known to date. The degree of tetrahedral cation ordering is very low in both zinnwaldites. Also, distortion characteristics of individual octahedra and tetrahedra in these zinnwaldites are very close to each other.
   A comparison of the details of structure of 1M and 2M1 biotite and 1M and 2M1 zinnwaldite gave no indication that a geometrical or other advantage is associated with either 2M1 or 1M stacking in zinnwaldite
Contributor
    Česká geologická služba
Contributor code
    ČGS (UNM)
Source format
    U
Entered date
    21. 2. 2008
Import date
    8. 8. 2012