Record details

    Minerals of spinel group from pyrope-bearing gravels of the České středohoří Mountains, Czech Republic
Statement of responsibility
    František Novák
Other titles
    Nerosty skupiny spinelu z pyroponosných štěrků v Českém středohoří, Česká republika
    Novák, František
Source title - serial
    Journal of the Czech Geological Society
    Vol. 46, no. 1-2
    p. 45-52
    České resumé
    Obsahuje bibliografické odkazy
    Zkr. název ser.: J. Czech geol. Soc.
Subject group
    asociace minerální
    kvartér Českého středohoří
    lokalita mineralogická
    proces sedimentační
Geographical name
    Podsedice (Litoměřice)
Abstract (in english)
   Spinel, ferroan spinel (pleonaste), chromian spinel (picotite), hercynite, magnetite and titanomagnetite were identified in a heavy mineral concentrate after industrial extraction of pyrope from pyrope-bearing near Podsedice in the České středohoří Mts. Very rare spinel occurs as dark grey grains exhibiting relatively enhanced content of FeO and Fe2O3. Ferroan spinel is the most abundant mineral of the spinel group, and amounts together with picotite to 17.5 wt%. The average composition is Mg 72, Fe2+ 28 (at.%) and atomic ratio Al/Fe 3+ = 11.9. Chromian variety of pleonaste with 10.3 wt.% Cr2O3 (11.2 at. %) is very rare. Pleonaste has a = 8.146(2) 10 -1nm and D calc % 3.848. Picotite composes about 30 wt.% of pleonaste grains. Picotite grains are smaller (< 4mm): Mg (72 at.%) predominated over Fe2+ (30 at.%) in its tetrahedral sites, and Al (58.5 at.%) predominates over Cr (36.5 at.%) and Fe 3+ (5.0 at. %) in octahedral sites.
   the content of Cr 2 O3 picotite varies between 26.89 and 37.35 wt.%. Hercynite is very rare. Magnetite plus titanomagnetite constitute 5.6 wt.% of the concentrate. Magnetite contains < 5.4 wt.% TiO2 and < 4.8 wt.% MnO. relatively higher concentration of MnO and the absence of MgO separate this mineral from titanomagnetic which has 10.90 - 12.07 wt.% TiO2. It is more abundant in the concentrate than magnetite. Its cell parameter a = 8.436 10 -1 nm and D calc = 4.845. Various types of basalt and its tuffs, basaltic pipe breccias and particularly xenoliths of various ultramafic rocks brought to the surface
    Česká geologická služba
Contributor code
    ČGS (UNM)
Source format
Entered date
    6. 3. 2008
Import date
    8. 8. 2012