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Crystal chemistry of rare earth elements in fluorapatite and some calc-silicates

Michael E. Fleet and Yuanming Pan
Crystal chemistry of rare earth elements in fluorapatite and some calc-silicates
European Journal of Mineralogy (June 1995) 7 (3): 591-605


The uptake of individual REE by fluorapatite and cuspidine has been studied by hydrothermal synthesis at approximately 700 degrees C and 0.1 GPa P (sub H2) O. The REE contents of fluorapatites crystallized with approximately 10 mol.% Ca (sub 4REE) (sub 6) (SiO (sub 4) ) (sub 6) F (sub 2) in the starting composition varies from 12 wt.% in Nd-fluorapatite to 3.2 wt.% in Lu-fluorapatite, showing preference for LREE over HREE. The uptake pattern is convex upwards, peaking at Nd, and has a double-'humped' appearance consistent with contribution from 4f crystal field stabilization energy. A similar uptake pattern is obtained for fluorapatites crystallized with approximately 2500 ppm REE in the starting composition. The experimental uptake patterns are similar to REE patterns of natural fluorapatites in some metamorphic and metasomatic rocks. Synthetic cuspidine coexisting with fluorapatite has a marked preference for HREE over LREE, and uptake is limited to the composition NaCa (sub 2REESi) (sub 2) O (sub 7) F (sub 2) . Bond valence calculation is a powerful first-approximation technique for deducing REE site preference of end-member calc-silicate mineral structures with multiple Ca positions (e.g. epidote-group minerals, vesuvianite, pumpellyite and cuspidine).

ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 7
Serial Issue: 3
Title: Crystal chemistry of rare earth elements in fluorapatite and some calc-silicates
Affiliation: University of Western Ontario, Department of Earth Sciences, London, ON, Canada
Pages: 591-605
Published: 199506
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 46
Accession Number: 1995-041703
Categories: General mineralogy
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 4 tables
Secondary Affiliation: University of Saskatchewan, CAN, Canada
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 199515
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