Record details

Title
    Potassium-bearing, fluorine-rich tourmaline from metamorphosed fluorite layer in leucocratic orthogneiss at Nedvědice, Svratka Unit, western Moravia
Statement of responsibility
    Milan Novák, Julie B. Selway, Stanislav Houzar
Other titles
    Draslík obsahující a fluorem bohatý turmalín z metamorfované fluoritové polohy v leukokratní ortorule z Nedvědice, svratecké krystalinikum
Author
    Houzar, Stanislav
    Novák, Milan, 1952-
    Selway, Julie B.
Language
    anglicky
Source title - serial
    Journal of the Czech Geological Society
Vol./nr.
    Vol. 43, no. 1-2
Pages
    p. 37-44
Year
    1998
Notes
    2 fot., 3 diagr., 2 tab., 27 bibl.
    České resumé
    Zkr. název ser.: J. Czech geol. Soc.
Subject group
    borosilikáty
    chemismus hornin
    cyklosilikáty
    draslík
    fluor
    ortorula
    prvky hlavní
    svratecké krystalinikum
    turmalín
Geographical name
    ČR-Morava
    Nedvědice (Žďár nad Sázavou)
Keyword
    Fluorine-rich
    Fluorite
    Layer
    Leucocratic
    Metamorphosed
    Moravia
    Nedvědice
    Orthogneiss
    Potassium-bearing
    Svratka
    Tourmaline
    Unit
    Western
Abstract (in english)
   hree tourmaline parageneses occur in orthogneiss and associated rocks at Nedvědice: (i) columns of black tourmaline, locally corroded, show patchy zoning with schorl dravite rims and dravite > schorl cores, and occur in a metamorphosed fluorite layer; (ii) black columnar crystals of accessory to subordinate homogenous schorl from leucocratic orthogneiss are locally concentrated in thin bands or in elongated clusters with quartz and muscovite; (iii) black columnar tourmaline crystals with schorl > dravite rims and dravite > schorl cores are heterogenous in thin section and BSE images, and occur in muscovite > biotite schists. Tourmaline from all three parageneses is characterized by high F (up to 0.77 apfu) and K (up to 0.09 apfu) in tourmaline from the metamorphosed fluorite layer.
   Two dominant substitutions were recognized in tourmaline: (1) Fe <-> Mg substitution in schorl-dravite from mica schists and metamorphosed fluorite layer; and (2) OH <-> F substitution typical for tourmaline from all rock types. Potassium rarely substitutes for Na at the X-site in the tourmaline structure. The chemical compositions suggest that K <-> Na, KFe3+ <-> NaAl and/or NaFe2+OH <-> KFe3+O substitutions may be responsible for K in tourmaline from Nedvědice
Contributor
    Česká geologická služba
Contributor code
    ČGS (UNM)
Source format
    U
Entered date
    18. 2. 2008
Import date
    8. 8. 2012