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The crystal structure determination and redefinition of matulaite, Fe (super 3+) Al (sub 7) (PO (sub 4) ) (sub 4) (PO (sub 3) OH) (sub 2) (OH) (sub 8) (H (sub 2) O) (sub 8) .8H (sub 2) O

A. R. Kampf, S. J. Mills, M. S. Rumsey, J. Spratt and G. Favreau
The crystal structure determination and redefinition of matulaite, Fe (super 3+) Al (sub 7) (PO (sub 4) ) (sub 4) (PO (sub 3) OH) (sub 2) (OH) (sub 8) (H (sub 2) O) (sub 8) .8H (sub 2) O
Mineralogical Magazine (June 2012) 76 (3): 517-534

Abstract

Matulaite was first described by Moore and Ito (1980) from the Bachman mine, Hellertown, Northampton County, Pennsylvania, USA. Its ideal formula was reported as CaAl (sub 18) (PO (sub 4) ) (sub 12) (OH) (sub 20) .28H (sub 2) O, based on wet-chemical analysis. Re-examination of both existing cotype specimens of matulaite revealed no material matching the powder or single-crystal X-ray diffraction data reported for the species. Other samples examined from the type locality, as well as from the LCA pegmatite in North Carolina, USA, and Fumade, Tarn, France, provided material crystallographically consistent with matulaite: P2 (sub 1) /n, a = 10.604(2), b = 16.608(4), c = 20.647(5) Aa, beta = 98.848(7) degrees and Z = 4. Electron microprobe and crystal structure analysis of newly studied material from the type locality showed the ideal formula of matulaite to be Fe (super 3+) Al (sub 7) (PO (sub 4) ) (sub 4) (PO (sub 3) OH) (sub 2) (OH) (sub 8) (H (sub 2) O) (sub 8) .8H (sub 2) O. The chemical composition reported by Moore and Ito (1980) was most probably determined on a mixture of mostly kobokoboite and afmite, with lesser amounts of crandallite. As there is no matulaite on any of the existing cotype specimens of the species, the two specimens used to obtain the new chemical analyses, powder and single-crystal X-ray diffraction data and the structure determination are designated as neotypes. The neotypes have also been used to obtain crystal morphology and new measurements of the physical and optical properties of the species. The neotypes and new data have been approved by the CNMNC, proposal 11-F. The crystal structure of matulaite contains seven-member chain segments of AlO (sub 6) octahedra decorated by PO (sub 4) tetrahedra. The PO (sub 4) tetrahedra also link to isolated FeO (sub 6) octahedra, resulting in a "pinwheel" Fe(PO (sub 4) ) (sub 6) group. The linkage of octahedra and tetrahedra defines a thick layer parallel to {001}. The only linkage between layers is via hydrogen bonding to interlayer water molecules.


ISSN: 0026-461X
EISSN: 1471-8022
Coden: MNLMBB
Serial Title: Mineralogical Magazine
Serial Volume: 76
Serial Issue: 3
Title: The crystal structure determination and redefinition of matulaite, Fe (super 3+) Al (sub 7) (PO (sub 4) ) (sub 4) (PO (sub 3) OH) (sub 2) (OH) (sub 8) (H (sub 2) O) (sub 8) .8H (sub 2) O
Affiliation: Natural History Museum of Los Angeles County, Mineral Sciences Department, Los Angeles, CA, United States
Pages: 517-534
Published: 201206
Text Language: English
Publisher: Mineralogical Society, London, United Kingdom
References: 7
Accession Number: 2012-092165
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 8 tables
N40°32'60" - N40°57'00", W75°37'60" - W75°02'60"
N43°19'60" - N44°12'00", E01°30'00" - E02°55'00"
Secondary Affiliation: Museum Victoria, AUS, AustraliaNatural History Museum, GBR, United Kingdom
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201248
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