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GEOREF RECORD

The crystal structure of stanekite, (Fe (super 3+) , Mn (super 2+) , Mg) (sub 2) [PO (sub 4) ]O, from Okatjimukuju, Karibib (Namibia), and its relationship to the polymorphs of synthetic Fe (sub 2) [PO (sub 4) ]O

Paul Keller, Falk Lissner and Thomas Schleid
The crystal structure of stanekite, (Fe (super 3+) , Mn (super 2+) , Mg) (sub 2) [PO (sub 4) ]O, from Okatjimukuju, Karibib (Namibia), and its relationship to the polymorphs of synthetic Fe (sub 2) [PO (sub 4) ]O
European Journal of Mineralogy (February 2006) 18 (1): 113-118

Abstract

Two monoclinic polytypes of staneckite were found at the type locality, Okatjimukuju, Karibib, Namibia. The crystal structure of staneckite-Mabc (a 11.835, b 6.328, c 9.984 Aa, beta 105.81 degrees , V 719.4 Aa (super 3) , Z = 8, space group I2/a) was determined from single-crystal X-ray intensity data and refined to R 0.0385. The other polytype, staneckite-Ma2bc (a 11.844, b 12.663, c 9.989 Aa, beta 105.93 degrees , Z = 16, space group P2 (sub 1) /a) is characterized by weak additional reflections and only the substructure could be refined to R 0.0450. Only small structural differences exist between the two polytypes. The crystal structure consists of a rather regular PO (sub 4) tetrahedron and two symmetrically different strongly distorted MO (sub 6) octahedra. Independent of their valency, the M cations are distributed over the octahedral sites. The MO (sub 6) octahedra share common edges to form zigzag chains running parallel to [010] for M1O (sub 6) and [100] for M2O (sub 6) , respectively. Both chain types are further interconnected by additional edges along the c axis to build an open framework that hosts the PO (sub 4) tetrahedra. Staneckite, synthetic alpha - and beta -Fe (sub 2) [PO (sub 4) }O are polymorphs, but in contrast to staneckite, the synthetic polymophs are characterized by face-sharing MO (sub 6) octahedra, which join together to straight or tightly folded zigzag chains for both beta -Fe (sub 2) [PO (sub 4) }O and beta -Fe (sub 2) [PO (sub 4) ]O-II or alpha -Fe (sub 2) [PO (sub 4) }O, respectively.


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 18
Serial Issue: 1
Title: The crystal structure of stanekite, (Fe (super 3+) , Mn (super 2+) , Mg) (sub 2) [PO (sub 4) ]O, from Okatjimukuju, Karibib (Namibia), and its relationship to the polymorphs of synthetic Fe (sub 2) [PO (sub 4) ]O
Affiliation: Universitaet Stuttgart, Instiut fuer Mineralogie und Kristallchemie, Stuttgart, Federal Republic of Germany
Pages: 113-118
Published: 200602
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 23
Accession Number: 2006-036666
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables
S21°58'60" - S21°58'60", E15°50'60" - E15°50'60"
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 200620
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