%0 Journal Article
%T Three Compositional Varieties of Rare-Earth Element Ore: Eudialyte-Group Minerals from the Norra K£¿rr Alkaline Complex, Southern Sweden
%A Axel S.L. Sj£¿qvist
%A David H. Cornell
%A Tom Andersen
%A Muriel Erambert
%A Mattias Ek
%A Magnus Leijd
%J Minerals
%D 2013
%I MDPI AG
%R 10.3390/min3010094
%X Agpaitic nepheline syenites at the Norra K£¿rr Alkaline Complex, southern Sweden, are rich in zirconium and rare-earth elements (REE), which are mainly accommodated in eudialyte-group minerals (EGM). Norra K£¿rr 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.
%K eudialyte-group minerals
%K agpaitic rocks
%K nepheline syenite
%K rare-earth elements
%K Norra K£¿rr Alkaline Complex
%K SEM-EDS
%K WDS-EMP
%U http://www.mdpi.com/2075-163X/3/1/94