Unique chondrodite-bearing mineral assemblage in marble at Bílá Hill near Čechočovice (western Moravia)Article PDF
Unique chondrodite-bearing mineral assemblage in marble at Bílá Hill near Čechočovice (western Moravia)
In the large body of pure calcite marble in the biotite paragneiss of Moldanubicum very rare chondrodite was found. It occurs in narrow limited layer of marble low in dolomite and silicate grains (<1 vol%) in assemblage with rare phlogopite, tremolite and chlorite, including accessory fluorapatite, ilmenite, zircon, uraninite, sporadic Ti-U-Nb oxide, galena, sphalerite and Ni-löllingite. Chondrodite is relatively rich in both iron (3.97–5.57 % wt. % FeO; 0.191–0.271 apfu Fe) and fluorine (5.98–7.03 % wt. % F; 1.100–1.284 apfu F), which differs from common chondrodites of Moldanubian Zone. The content of Ti fluctuates in the range 0.13–1.93% TiO2 (0.006–0.084 apfu Ti) and Mn 0.12–0.24% MnO (0.006–0.012 apfu Mn), Zn is ≤ 0.11% ZnO (≤0.005 apfu Zn). The ratio of MTi/Si varies between 2.45–2.47 (Table 1) corresponds to that in chondrodite. Flogopite has a slightly increased content Ba (0.23–0.42 wt. % BaO, 0.006–0.012 apfu Ba), tremolite is poor in Al and Fe. Zircon contains up to 1.42 wt. % HfO2 (≤0.013 apfu Hf) and uraninite is relatively rich Th (24.75–34.02 wt.% ThO2, 0.225–0.423 apfu Th). The mineral assemblage of chondrodite was originated by influx of F-, Fe-, U-, Zr- and Mg-bearing fluids that infiltrated from an external source.
Stanislav Houzar, Department of Mineralogy and Petrography, Moravian Museum, Zelný trh 6, 659 37 Brno, Czech Republic, e-mail: firstname.lastname@example.org
Petr Gadas, Department of Geological Sciences, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic, e-mail: email@example.com