title: Cu- and Mn-bearing tourmalines from Brazil and Mozambique: crystal structures, chemistry and correlations.
abstract: Cu- and Mn-bearing tourmalines from Brazil and Mozambique were characterised chemically (EMPA and LA-ICP-MS) and by X-ray single-crystal structure refinement. All these samples are rich in Al, Li and F (fluor-elbaite) and contain significant amounts of CuO (up to ~1.8 wt%) and MnO (up to ~3.5 wt%). Structurally investigated samples show a pronounced positive correlation between the <Y-O> distances and the (Li + Mn2++ Cu + Fe2+) content (apfu) at this site withR2= 0.90. An excellent negative correlation exists between the <Y-O> distances and the Al2O3content (R2= 0.94). The samples at each locality generally show a strong negative correlation between theX-site vacancies and the (MnO + FeO) content. The Mn content in these tourmalines depends on the availability of Mn, on the formation temperature, as well as on stereochemical constraints. Because of a very weak correlation between MnO and CuO we believe that the Cu content in tourmaline is essentially dependent on the availability of Cu and on stereochemical constraints.
authors.affiliation: Institut für Mineralogie und Kristallographie, Geozentrum, Universität Wien, Althanstr. 14, 1090 Wien, Austria.
authors.forename: Andreas
authors.initials: A
authors.lastname: Ertl
authors.affiliation: Institut für Mineralogie und Kristallographie, Geozentrum, Universität Wien, Althanstr. 14, 1090 Wien, Austria.
authors.forename: Gerald
authors.initials: G
authors.lastname: Giester
authors.affiliation: Lehrstuhl für Geodynamik und Geomaterialforschung, Institut für Geographie und Geologie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Schüssler
authors.affiliation: Geozentrum Nordbayern, Universität Erlangen, Schlossgarten 5a, 91054 Erlangen, Germany.
authors.forename: Helene
authors.initials: H
authors.lastname: Brätz
authors.affiliation: Lehrstuhl für Geodynamik und Geomaterialforschung, Institut für Geographie und Geologie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Okrusch
authors.affiliation: Institut für Mineralogie und Kristallographie, Geozentrum, Universität Wien, Althanstr. 14, 1090 Wien, Austria.
authors.forename: Ekkehart
authors.initials: E
authors.lastname: Tillmanns
authors.affiliation: Gebrüder Bank, Dietzenstrasse 1, 55743 Idar-Oberstein, Germany.
authors.forename: Hermann
authors.initials: H
authors.lastname: Bank