New occurrence of grandidierite, ominelite, boralsilite and Fe-rich werdingite in Horní Bory, Czech Republic – overviewArticle PDF
New occurrence of grandidierite, ominelite, boralsilite and Fe-rich werdingite in Horní Bory, Czech Republic – overview
A new occurrence of four anhydrous borosilicates (grandidierite, ominelite, boralsilite, Fe-rich werdingite) was found in Horní Bory quarry, Bory Granulite Massif, Moldanubicum, Czech Republic. The borosilicates were found associated with dumortierite, tourmaline and corundum. They occur in a thin veinlet (Kfs + Qtz ± Pl) cross-cutting a leucocratic, garnet- and kyanite-bearing granulite. Primary grandidierite to ominelite is enclosed in quartz; its crystals are locally overgrown by prismatic aggregates of boralsilite and Fe-rich werdingite. Boralsilite also occurs as separate radial aggregates with Fe-rich werdingite in quartz. Grandidierite-ominelite is commonly rimmed by a narrow zone of secondary tourmaline or is partially replaced by the assemblage tourmaline + corundum ± hercynite. Other accessory minerals in the veinlet involve monazite-(Ce), ilmenite, rutile to Nb-rich rutile, ferberite to Nb,Sc-rich ferberite, srilankite, löllingite, arsenopyrite and apatite.
Jan Cempírek, Department of Mineralogy and Petrography, Moravian Museum, Zelný trh 6, 659 37 Brno, Czech Republic
Milan Novák, Department of Geological Sciences, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic
Zdeněk Dolníček, Department of Geology, Palacky University in Olomouc, Tř. 17. listopadu 12, 771 46 Olomouc, Czech Republic