Incorporation of REE into leucophanite: a compositional and structural study

Henrik Friis Mortensen; Tonci Balic Zunic; C.T. Williams; R. Garcia-Sanchez

doi:10.1180/minmag.2007.071.6.625

Incorporation of REE into leucophanite: a compositional and structural study

Henrik Friis Mortensen, Tonci Balic Zunic, C.T. Williams, R. Garcia-Sanchez

Geology

5 Citations (Scopus)

Abstract

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.

Original language	English
Journal	Mineralogical Magazine
Volume	71
Issue number	6
Pages (from-to)	625-640
ISSN	0026-461X
DOIs	https://doi.org/10.1180/minmag.2007.071.6.625
Publication status	Published - 2007

Keywords

Faculty of Science
leucophanite
Crystal Chemistry
alkaline complexes
crystal twins

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10.1180/minmag.2007.071.6.625

Cite this

@article{d69a64f0ea4111deba73000ea68e967b,

title = "Incorporation of REE into leucophanite: a compositional and structural study",

abstract = "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.",

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author = "Mortensen, {Henrik Friis} and {Balic Zunic}, Tonci and C.T. Williams and R. Garcia-Sanchez",

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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

SN - 0026-461X

VL - 71

SP - 625

EP - 640

JO - Mineralogical Magazine

JF - Mineralogical Magazine

IS - 6

ER -