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Crystal structure of nanlingite; the first mineral with a [Fe(AsO (sub 3) ) (sub 6) ] configuration

Yang Zhuming, Gerald Giester, Ding Kuishou and Ekkehart Tillmanns
Crystal structure of nanlingite; the first mineral with a [Fe(AsO (sub 3) ) (sub 6) ] configuration
European Journal of Mineralogy (January 2011) 23 (1): 63-71

Abstract

Nanlingite was first described as a new mineral from a dolomitic limestone along a contact between greisenized granite and dolomitic limestone in the Nanling area, Hunan Province, China. The structure was solved and refined on single-crystal X-ray data in space group R3m, with a=10.2114(10), c=25.689(3) Aa, V=2319.2(6) Aa (super 3) , to R1=0.021, wR2=0.049. The chemical formula of nanlingite is Na(Ca, Li, Na) (sub 6) (Mg, Fe) (sub 12) (AsO (sub 3) ) (sub 2) [Fe(AsO (sub 3) ) (sub 6) ]F (sub 14) with Z=3 according to the crystal structure refinement. The complex framework is formed by edge- and corner-sharing of distorted NaF (sub 8) and CaF (sub 4) O (sub 4) cubes, MgF (sub 2) O (sub 4) octahedra, and AsO (sub 3) trigonal pyramids. The lithium atom occupies (22%) the split site at 0.58(2) Aa from the main Ca site and exhibits a five-fold coordination with <Li-(O,F)>2.21 Aa. The iron atom (at 3b, site symmetry 3m) is surrounded by six As atoms of AsO (sub 3) groups at a distance of 2.40 Aa with the lone-pair electrons pointing towards the central atom. This [Fe(AsO (sub 3) ) (sub 6) ] cluster is a novel configuration in the crystal chemistry of minerals. According to Mossbauer spectra and electron energy-loss spectroscopy data the oxidation state of Fe in nanlingite is mainly Fe (super II) with a low-spin state. In the configuration of arsenite groups, the distance <As(2)-O>=1.73 Aa of the [Fe(AsO (sub 3) ) (sub 6) ] clusters is shorter than the normal range. The empirical crystal-chemical formula for nanlingite is (Na (sub 0.90) Li (sub 0.10) )Sigma (sub 1.00) (Ca (sub 4.41) Li (sub 1.06) Mg (sub 0.17) Na (sub 0.06) Mn (sub 0.05) [] (sub 0.25) )Sigma (sub 6.00) (Mg (sub 11.38) Fe (super 3+) (sub 0.30) Al (sub 0.29) Ti (sub 0.03) )Sigma (sub 12.00) (AsO (sub 3) ) (sub 2) [Fe (super II) (AsO (sub 3) ) (sub 6) ](F (sub 13.77) OH (sub 0.16) )Sigma (sub 13.93) .


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 23
Serial Issue: 1
Title: Crystal structure of nanlingite; the first mineral with a [Fe(AsO (sub 3) ) (sub 6) ] configuration
Affiliation: Chinese Academy of Sciences, Institute of Geology and Geophysics, Key Laboratory of Engineering Geomechanics, Beijing, China
Pages: 63-71
Published: 201101
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Germany
References: 15
Accession Number: 2011-026558
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 6 tables
N24°40'00" - N30°10'00", E109°00'00" - E114°15'00"
N24°30'00" - N26°30'00", E111°00'00" - E114°00'00"
Secondary Affiliation: Universitaet Wien, AUS, Australia
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Schweizerbart'sche Verlagsbuchhandlung. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201115
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