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The crystal structure of johnbaumite, Ca (sub 5) (AsO (sub 4) ) (sub 3) OH, the arsenate analogue of hydroxylapatite

Cristian Biagioni and Marco Pasero
The crystal structure of johnbaumite, Ca (sub 5) (AsO (sub 4) ) (sub 3) OH, the arsenate analogue of hydroxylapatite
American Mineralogist (August 2013) 98 (8-9): 1580-1584

Abstract

The crystal structure of johnbaumite, ideally Ca (sub 5) (AsO (sub 4) ) (sub 3) OH, was determined and refined using crystals from the Harstigen mine, Varmland, Sweden, on the basis of X-ray diffraction data. The structure was refined to R (sub 1) = 0.038 in space group P6 (sub 3) /m, with unit-cell parameters a = 9.7242(2), c = 6.9657(9) Aa, and V = 570.43(2) Aa (super 3) . The chemical composition of the sample, determined by electron-microprobe analysis, is (Ca (sub 5.02) Pb (sub 0.03) ) (sub Sigma 5.05) [As (sub 2.91) P (sub 0.04) Si (sub 0.02) ] (sub Sigma 2.97) O (sub 12) (OH (sub 0.97) Cl (sub 0.03) ). Johnbaumite belongs to the calcium arsenate apatites, together with svabite, Ca (sub 5) (AsO (sub 4) ) (sub 3) F, and turneaureite, Ca (sub 5) (AsO (sub 4) ) (sub 3) Cl. Johnbaumite is topologically similar to the other members of the apatite supergroup: columns of face-sharing M1 polyhedra run along c and are connected through TO (sub 4) tetrahedra, giving rise to a zeolite-like microporous framework, with channels hosting M2 cations and X anions. This is the first published single-crystal structure study of johnbaumite and the first report of this calcium arsenate apatite from the Harstigen mine. Actually, johnbaumite was identified at this locality at the end of the 19th Century but it was described as svabite.


ISSN: 0003-004X
EISSN: 1945-3027
Coden: AMMIAY
Serial Title: American Mineralogist
Serial Volume: 98
Serial Issue: 8-9
Title: The crystal structure of johnbaumite, Ca (sub 5) (AsO (sub 4) ) (sub 3) OH, the arsenate analogue of hydroxylapatite
Affiliation: Universita di Pisa, Dipartimento di Scienze della Terra, Pisa, Italy
Pages: 1580-1584
Published: 201308
Text Language: English
Publisher: Mineralogical Society of America, Washington, DC, United States
References: 23
Accession Number: 2013-073841
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 6 tables
N58°52'60" - N61°02'60", E01°42'00" - E14°30'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Mineralogical Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201344
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