Details

Autor(en) / Beteiligte

• Sjöqvist, Axel
• Cornell, David
• Andersen, Tom
• Erambert, Muriel
• Ek, Mattias
• Leijd, Magnus

Titel

Three Compositional Varieties of Rare-Earth Element Ore: Eudialyte-Group Minerals from the Norra Kärr Alkaline Complex, Southern Sweden

Ist Teil von

• Minerals (Basel), 2013-03, Vol.3 (1), p.94-120

Ort / Verlag

Basel: MDPI AG

Erscheinungsjahr

2013

Link zum Volltext

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• Agpaitic nepheline syenites at the Norra Kärr Alkaline Complex, southern Sweden, are rich in zirconium and rare-earth elements (REE), which are mainly accommodated in eudialyte-group minerals (EGM). Norra Kärr hosts three compositionally distinct groups of EGM, which are complex zirconosilicates. Analyses of EGM by electron beam energy-dispersive (SEM-EDS) and wavelength-dispersive (WDS-EMP) X-ray microanalysis are presented and compared, complemented by whole-rock analyses. The SEM-EDS and WDS-EMP methods produce comparable results for most elements. Considering that most SEM instruments have a user-friendly EDS system, it is a useful tool for reconnaissance work in research and especially in exploration-related studies. The EGM evolved markedly from an initial Fe-rich and REE-poor, but HREE-dominated variety, to an intermediate Fe-Mn and HREE-rich one, and to a final Mn- and LREE-rich variety, which occur in rocks classified as lakarpite and grennaite. Based on the Mn/(Fe+Mn) ratios of the EGM, this trend is interpreted as a result of magmatic evolution. The threefold diversity of EGM presented in this work is much broader than has previously been documented.