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GEOREF RECORD

Segelerite from the Mount Deverell variscite deposit, Western Australia; hydrogen bonding and relationship to jahnsite

Ian E. Grey, W. Gus Mumme, Peter J. Downes, Benjamin A. Grguric and Robert W. Gable
Segelerite from the Mount Deverell variscite deposit, Western Australia; hydrogen bonding and relationship to jahnsite
European Journal of Mineralogy (January 2019) 31 (3): 465-471

Abstract

The crystal structure of segelerite, Ca (sub 2) Mg (sub 2) Fe (sub 1.4) (super 3+) Al (sub 0.6) (PO (sub 4) ) (sub 4) (OH) (sub 2) (H (sub 2) O) (sub 8) , from the Mount Deverell variscite deposit, Western Australia, has been refined using single-crystal X-ray data to wR (sub obs) =0.048 for 2082 unique reflections and all H atoms were located during the refinement. Cell parameters are a=14.7772(2) Aa, b=18.7079(2) Aa, c=7.2424(1) Aa, space group Pbca. The H-bonding scheme is described and compared to that for the combinatorial polymorph, jahnsite. The crystal structures of both minerals comprise heteropolyhedral slabs of composition [XM1Fe (sub 2) (super 3+) (OH) (sub 2) (PO (sub 4) ) (sub 4) ], that are linked together via corner-sharing of PO (sub 4) tetrahedra with isolated [M2(O (sub p) ) (sub 2) (H (sub 2) O) (sub 4) ] octahedra. The structures differ in the mode of linkage of the M2 octahedra, which is via trans O (sub p) ligands in segelerite and via both trans and cis O (sub p) ligands in jahnsite. In segelerite, X=M1=Ca, whereas in jahnsite-group minerals, X=Ca, Na, Mn (super 2+) and M1=Mn (super 2+) , Mg (super 2+) , Fe (super 2+) , Fe (super 3+) . X and M1 alternate along the 7 Aa axis and it is proposed that different magnitudes of rotation of the Fe (super 3+) octahedra about the 7 Aa axis to accommodate the different coordination requirements of the X and M1 cations drives the symmetry changes in the two minerals so that a strong H-bonding network is maintained.


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 31
Serial Issue: 3
Title: Segelerite from the Mount Deverell variscite deposit, Western Australia; hydrogen bonding and relationship to jahnsite
Affiliation: CSIRO Mineral Resources, Welshpool, West. Aust., Australia
Pages: 465-471
Published: 20190109
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Germany
References: 17
Accession Number: 2019-014663
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 4 tables
S24°59'27" - S24°59'27", E118°12'10" - E118°12'10"
Secondary Affiliation: Western Australian Museum, AUS, AustraliaUniversity of Western Australia, AUS, AustraliaUniversity of Melbourne, AUS, Australia
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Abstract, copyright, Schweizerbart'sche Verlagsbuchhandlung. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201910
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