Mn-rich tourmaline and fluorapatite in a Variscan pegmatite from Eibenstein an der Thaya,Bohemian massif, Lower Austria
- Autor(en)
- Andreas Ertl, Ralf Schuster, Stefan Prowatke, Franz Brandstätter, Thomas Ludwig, Heinz-Jürgen Bernhardt, Friedrich Koller, John M. Hughes
- Abstrakt
Mn-rich tourmaline (up to 8.89 wt% MnO) and fluorapatite (up to 9.15 wt% MnO) occur in an elbaite-subtype pegmatite from the Drosendorf Complex (near Eibenstein an der Thaya, Bohemian massif, Austria). Based on geological and radiometrical data (337 ‘ 5 Ma from Sm/Nd garnet-albite isochron) the pegmatite might be related to the Variscan Rastenberg type granodiorites or Weinsberg type granites. Coexisting minerals with Mn-rich, pink-brown to yellow-brown tourmaline and bluish, Mn-rich fluorapatite are quartz, feldspars, Mn-rich garnet (63 mol% spessartine), pink Mn-bearing muscovite (up to ~0.3 wt% MnO), topaz, cassiterite and rarely, beryl and bertrandite. Tourmaline composition evolves from Mn-poor (0.09 apfu) schorl through Al-rich Mn-bearing (0.15-0.33 apfu) schorl, Mn-rich (0.58 apfu) Fe-bearing olenite-elbaite to Mn-rich (0.86-1.27 apfu) olenite-elbaite, which reflects the Mn-enrichment of the pegmatite system during the late stages of its evolution. Mn-rich Li-bearing olenite has the formulae X(Na0.71Ca0.01?0.28) [(OH)3 (F0.44,OH,O)] (8.89 wt% MnO) and X(Na0.84Ca0.03 K0.01?0.12) Y(Al1.33Mn2+0.086Li0.51 Fe2+0.06 Ti0.02?0.22)ZAl6.00T(Si5.74Al0.26) B3 O27 [(OH)3(F0.54OH0.37 O0.09)] (6.22 wt% MnO), with lattice parameters a = 15.9158(4) A°, c = 7.1201 (2) A° (R=0.021). This pegmatite has two different zones: a Mn-enriched zone and a Mg-enriched zone. The younger, fine-grained, Mn-enriched zone contains the Mn-bearing minerals described above which have low Mg contents. The coarse-grained, Mg-enriched zone contains Mg-bearing muscovite, tourmaline from the dravite-schorl series, and pale-green fluorapatite but essentially contains no Mn-bearing minerals. Interestingly, albite has a pale bluish-greenish color in the Mn-enriched zone while it has a white color in the Mg-enriched zone. Œ 2004 E. Schweizerbart'sche Verlagsbuchhandlung.
- Organisation(en)
- Institut für Mineralogie und Kristallographie
- Externe Organisation(en)
- Universität Heidelberg, Geologisk Museum, Ruhr-Universität Bochum (RUB), Miami University
- Journal
- European Journal of Mineralogy: an international journal of mineralogy, geochemistry and related sciences
- Band
- 16
- Seiten
- 551-560
- Anzahl der Seiten
- 10
- ISSN
- 0935-1221
- Publikationsdatum
- 2004
- Peer-reviewed
- Ja
- ÖFOS 2012
- 1051 Geologie, Mineralogie
- Link zum Portal
- https://ucrisportal.univie.ac.at/de/publications/be2eb021-271f-4ab7-90a7-3687a124a3c6