Incorporation of REE into leucophanite: a compositional and structural study
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Incorporation of REE into leucophanite : a compositional and structural study. / Mortensen, Henrik Friis; Balic Zunic, Tonci; Williams, C.T.; Garcia-Sanchez, R.
I: Mineralogical Magazine, Bind 71, Nr. 6, 2007, s. 625-640.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Incorporation of REE into leucophanite
T2 - a compositional and structural study
AU - Mortensen, Henrik Friis
AU - Balic Zunic, Tonci
AU - Williams, C.T.
AU - Garcia-Sanchez, R.
PY - 2007
Y1 - 2007
N2 - The crystal structures of nine, and the chemical compositions of ten, natural samples of leucophanite, ideally NaCaBeSi2O6F, were investigated. The analysed samples display a large compositional variation with trace-element abundances >50,000 ppm, primarily due to rare earth elements (REE). Fromthese data, we propose a substitution scheme for the incorporation of REE for Ca, with additional Na substituting for Ca and the generation of vacancies to ensure charge balance. Compositional zonation was observed in some samples; this zonation correlates with variations in cathodoluminescence. The crystal structure of the nine analysed samples could all be refined in space group P212121. We found no evidence for a reduction of symmetry with increased trace-element concentration. Various twin combinations were observed and these seem related to crystallization conditions rather than structural or chemical factors.
AB - The crystal structures of nine, and the chemical compositions of ten, natural samples of leucophanite, ideally NaCaBeSi2O6F, were investigated. The analysed samples display a large compositional variation with trace-element abundances >50,000 ppm, primarily due to rare earth elements (REE). Fromthese data, we propose a substitution scheme for the incorporation of REE for Ca, with additional Na substituting for Ca and the generation of vacancies to ensure charge balance. Compositional zonation was observed in some samples; this zonation correlates with variations in cathodoluminescence. The crystal structure of the nine analysed samples could all be refined in space group P212121. We found no evidence for a reduction of symmetry with increased trace-element concentration. Various twin combinations were observed and these seem related to crystallization conditions rather than structural or chemical factors.
KW - Faculty of Science
KW - leucophanite
KW - krystal kemi
KW - leucophanite
KW - Crystal Chemistry
KW - alkaline complexes
KW - crystal twins
U2 - 10.1180/minmag.2007.071.6.625
DO - 10.1180/minmag.2007.071.6.625
M3 - Journal article
VL - 71
SP - 625
EP - 640
JO - Mineralogical Magazine
JF - Mineralogical Magazine
SN - 0026-461X
IS - 6
ER -
ID: 16304376