The crystal structures of kidwellite and ‘laubmannite’, two complex fibrous iron phosphates

Kolitsch, Uwe

doi:10.1180/0026461046810177

Cited by 6 publications

(2 citation statements)

References 7 publications

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“…A complete characterisation of the mineral was only possible after a crystal fragment was finally found that was suitable for a single-crystal structure determination. A preliminary characterisation of the new mineral was given by Kolitsch et al (2004). The mineral and its name were unanimously approved by the Commission on New Minerals and Minerals Names, IMA (no.…”

Section: Introductionmentioning

confidence: 99%

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Allanpringite, Fe3(PO4)2(OH)35H2O, a new ferric iron phosphate from Germany, and its close relation to wavellite

Kolitsch

Bernhardt

Lengauer

et al. 2006

ejm

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Allanpringite is a new ferric iron phosphate with the ideal formula Fe 3 (PO 4) 2 (OH) 3 •5H 2 O, and is closely related to wavellite, Al 3 (PO 4) 2 (OH) 3 •5H 2 O. Type locality is the dump of the abandoned Grube Mark near Essershausen, ca. 5 km SE of Weilburg/Lahn, Taunus, Hesse, Germany. The mineral occurs as pale brown-yellow, [010] acicular, invariably twinned (by nonmerohedry) crystals which are always intergrown to form bundles of subparallel individuals. The maximum length of crystals is ca. 1.5 mm (usually much smaller); bundles can reach up to about 2 mm. The mineral is associated with beraunite (reddish "oxiberaunite" variety), cacoxenite, strengite and cryptomelane. Allanpringite is translucent to transparent, its streak is white with a pale yellowish tint, and it has a vitreous lustre. It shows a perfect cleavage parallel to the morphological elongation and one good cleavage parallel to {010}. It is brittle and has an uneven fracture, a Mohs hardness of ' 3, and D(meas.) = 2.54(2) g/cm 3 , D(calc.) = 2.583 g/cm 3 (for empirical formula). Optically, it is biaxial positive, with [ = 1.662(5), q = 1.675(5), * = 1.747(5), 2V * (calc.) = 48°; pleochroism is strong: X colourless, Y colourless, Z dark yellow; absorption Z>>X ' Y; orientation XYZ = **b (pseudoorthorhombic); no visible dispersion. Electron microprobe analysis yielded (wt. %): Fe 2 O 3 47.84, Al 2 O 3 0.34, Mn 2 O 3 0.04; CuO 0.08, P 2 O 5 28.56, F 0.02, H 2 O calc 23.49, less O≡F 0.01, total 100.36. The empirical formula is (Fe 2.98 Al 0.03)(PO 4) 2 (OH 3.02 F 0.01)•4.97H 2 O, based on 16 O atoms. Allanpringite is monoclinic, space group P2 1 /n, with a = 9.777(3), b = 7.358(2), c = 17.830(5) Å, q = 92.19(4)°, V = 1281.7(6) Å 3 (single-crystal data) and Z = 4. Strongest lines in the X-ray powder diffraction pattern are [d (Å), I, hkl]: 8.90 (100) (002), 8.41 (60) (10-1, 101), 5.870 (50) (110), 3.600 (50) (021, 02-1), 3.231 (80) (204, 12-2). The crystal structure has been determined using singlecrystal X-ray diffraction data (MoK [ radiation, CCD area detector) obtained from a twinned fragment (R(F) = 13.3 %). The structure of allanpringite is a monoclinically distorted, pseudo-orthorhombic variant of the orthorhombic structure of its Al-analogue wavellite, Al 3 (PO 4) 2 (OH,F) 3 •5H 2 O. Chains of corner-sharing, distorted Fe(O,OH,H 2 O) 6 octahedra parallel to [010] are corner-linked by PO 4 tetrahedra. Channels, also parallel to [010], host a positionally split water molecule. Average Fe-O distances of the three nonequivalent Fe atoms range between 2.014 and 2.021 Å. Single-crystal laser-Raman spectroscopy confirms an overall weak hydrogen bonding scheme. The structure of allanpringite is also related to those of kingite and mitryaevaite. The amorphous santabarbaraite has a chemical formula basically identical to that of allanpringite. The name honours Dr. Allan Pring, eminent Australian mineralogist.

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Section: Introductionmentioning

confidence: 99%

“…The present work is part of studies devoted to the crystal chemistry of several complex fibrous iron phosphate minerals (Kolitsch, 1999(Kolitsch, , 2001(Kolitsch, , 2004.…”

Section: Introductionmentioning

confidence: 99%

Allanpringite, Fe3(PO4)2(OH)35H2O, a new ferric iron phosphate from Germany, and its close relation to wavellite

Kolitsch

Bernhardt

Lengauer

et al. 2006

ejm

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The molecular structure of the phosphate mineral kidwellite NaFe93+(PO4)6(OH)11⋅3H2O – A vibrational spectroscopic study

Frost

López

Theiss

et al. 2014

Journal of Molecular Structure

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A new pseudo-polymorph in mineral sphenicidite family (NH4)[Fe2(OH)(H2O)(PO4)2]·1.5H2O exhibiting spontaneous magnetization below 25 K

Zhou

Duan

Zhang

et al. 2010

Solid State Sciences

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The crystal structures of kidwellite and ‘laubmannite’, two complex fibrous iron phosphates

Abstract: The previously unknown, complex crystal structures of two fibrous ferric iron phosphate minerals have been solved using single-crystal X-ray diffraction data. The structure of a slightly arsenatian kidwellite has been refined in space group P2/c (a = 20.117 (4)

Cited by 6 publications

References 7 publications

Allanpringite, Fe3(PO4)2(OH)35H2O, a new ferric iron phosphate from Germany, and its close relation to wavellite

Allanpringite, Fe3(PO4)2(OH)35H2O, a new ferric iron phosphate from Germany, and its close relation to wavellite

The molecular structure of the phosphate mineral kidwellite NaFe93+(PO4)6(OH)11⋅3H2O – A vibrational spectroscopic study

A new pseudo-polymorph in mineral sphenicidite family (NH4)[Fe2(OH)(H2O)(PO4)2]·1.5H2O exhibiting spontaneous magnetization below 25 K

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