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Pattersonite, PbFe (sub 3) (PO (sub 4) ) (sub 2) (OH) (sub 4) [(H (sub 2) O) (sub 0.5) (OH) (sub 0.5) ] (sub 2) , a new supergene phosphate mineral; description and crystal structure

Uwe Kolitsch, Heinz-Juergen Bernhardt, Werner Krause and Guenter Blass
Pattersonite, PbFe (sub 3) (PO (sub 4) ) (sub 2) (OH) (sub 4) [(H (sub 2) O) (sub 0.5) (OH) (sub 0.5) ] (sub 2) , a new supergene phosphate mineral; description and crystal structure
European Journal of Mineralogy (May 2008) 20 (2): 281-288

Abstract

Pattersonite, PbFe (sub 3) (PO (sub 4) ) (sub 2) (OH) (sub 4) [(H (sub 2) O) (sub 0 5) (OH) (sub 0 5) ] (sub 2) , is a new supergene lead iron(III) phosphate mineral. It was discovered in a single boulder on the dumps of the Grube Vereinigung, near Eisenbach, Taunus, Hesse, Germany. The mineral forms aggregates of dark yellow, subparallel, pinacoidal plates up to 0.5 mm in size, and is accompanied by goethite, kintoreite and (rare) pyromorphite. Pattersonite is translucent, with a very pale yellow streak and adamantine luster. It is brittle and shows one poor cleavage of unknown orientation, conchoidal fracture, a Mohs hardness of 4 1/2 (VHN (sub 25) = 530(80) kg/mm (super 2) ), and has D(meas.) >4.04, D(calc.) 4.17 g/cm (super 3) (from crystal-structure solution). Optically, it is biaxial negative, with alpha = 1.86(1), beta = 1.917 (calc.), gamma = 1.93(1), 2V (sub alpha ) = 50(5) degrees . Dispersion is very strong (r > v) and the pleochroism is weak, X = nearly colorless to very pale yellow, Y = pale yellow to yellow, Z = yellow to dark yellow (depending on grain size), with absorption Z > Y > X. Orientation (polar coordinates in terms of {phi} and rho based on (010) = 0 degrees /90 degrees ) is X (-113 degrees /85 degrees ); Y (155 degrees /70 degrees ); Z (-10 degrees /21 degrees ). Pattersonite is non-fluorescent. The mineral is triclinic, space group P[Formula: see text] (No. 2), with a = 5.309(1), b = 7.211(1), c = 7.349(1) Aa, alpha = 87.74(3), beta = 86.38(3), gamma = 71.40(3) degrees , V = 266.06(7) Aa (super 3) (single-crystal data), and Z = 1. Strongest lines in the X-ray powder diffraction pattern are [d in Aa (I (sub calc) ) (hkl)]: 4.848 (100) (110), 6.839 (64) (0-10), 3.547 (57) (1-10), 3.417 (52) (0-20), 3.022 (51) (112), 3.667 (47) (00-2), 2.8339 (45) (11-2). The crystal structure was determined from single-crystal X-ray diffraction data (Mo-K alpha , CCD area detector, R(F) = 5.6 %). The chemical formula obtained, PbFe (sub 3) (PO (sub 4) ) (sub 2) (OH) (sub 4) [(H (sub 2) O) (sub 0 5) (OH) (sub 0 5) ] (sub 2) , is in good agreement with quantitative electron microprobe analysis which also indicated negligible amounts of impurity elements. The unique crystal structure consists of an interrupted three-dimensional framework based on intersecting zig-zag chains of corner-sharing FeO (sub 6) octahedra, linked by PO (sub 4) tetrahedra. The [8]-coordinated Pb atom is located within elliptical [100] channels. The asymmetric unit contains one unique Pb, three Fe, one P, seven O (two of which represent OH groups and one a mixed [(H (sub 2) O) (sub 0 5) (OH) (sub 0 5) ] ligand with a calculated bond-valence sum of 0.75 valence units) and 3.5 H atoms. The coordination environment of the Pb (super 2+) cation can be described as a monoclinically distorted cuboid; the lone electron pair on the cation is not stereochemically active. Average Pb-O, Fe-O and P-O bond lengths are 2.65, 2.02 and 1.53 Aa, respectively. Single-crystal laser-Raman spectroscopy is used to describe the vibrational properties. The new mineral may be considered a dimorph of kintoreite, ideally PbFe (sub 3) (PO (sub 4) ) (sub 2) (OH,H (sub 2) O) (sub 6) , a member of the alunite super-group. The structure is, however, only remotely similar to that of kintoreite. The apparent rarity of the new mineral suggests it may be metastable with respect to kintoreite. The name honors Arthur Lindo Patterson (1902-1966), innovative crystallographer who devised the well-known Patterson method.


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 20
Serial Issue: 2
Title: Pattersonite, PbFe (sub 3) (PO (sub 4) ) (sub 2) (OH) (sub 4) [(H (sub 2) O) (sub 0.5) (OH) (sub 0.5) ] (sub 2) , a new supergene phosphate mineral; description and crystal structure
Affiliation: Naturhistorisches Museum, Mineralogisch-Petrographische Abteilung, Vienna, Austria
Pages: 281-288
Published: 200805
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 23
Accession Number: 2008-086487
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 6 tables
N49°22'60" - N51°40'00", E07°45'00" - E10°15'00"
Secondary Affiliation: Ruhr-Universitaet Bochum, DEU, Federal Republic of Germany
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: 200826
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