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Frost, Ray, Xi, Yunfei,& Palmer, Sara (2011) Molecular structure of the mineral woodhouseite CaAl3(PO4,SO4)2(OH)6. Journal of Molecular Structure, 1001(1 - 3), pp. 56-61.

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CaAl3(PO4,SO4)2(OH)6

Ray L. Frost,  Yunfei Xi and Sara J. Palmer

Chemistry Discipline, Faculty of Science and Technology, Queensland University of Technology, GPO Box 2434, Brisbane Queensland 4001, Australia.

ABSTRACT

The mineral woodhouseite CaAl3(PO4,SO4)2(OH)6 is a hydroxy phosphate-sulphate mineral belonging to the beudantite subgroup of , and has been characterised by Raman spectroscopy, complimented with infrared spectroscopy. Bands at various wavenumbers were assigned to the different vibrational modes of woodhouseite, which were then associated to the molecular structure of the mineral. Bands were primarily assigned to phosphate and sulphate stretching and bending modes. Two symmetric stretching modes for both phosphate and sulphate supported the concept of non-equivalent phosphate and sulphate units in the mineral structure. Bands in the OH stretching region enabled hydrogen bond distances to be calculated.

KEYWORDS: woodhouseite, svanbergite, crandallites, phosphate, sulphate, Raman spectroscopy

 Author to whom correspondence should be addressed ([email protected]) 1

INTRODUCTION

The mineral woodhouseite CaAl3(PO4,SO4)2(OH)6 is a calcium-aluminium hydroxyl phosphate-sulphate [1, 2]. The mineral belongs to the beudantite mineral group with general

formula AB3(XO4)(SO4)(OH)6 where A is Ca, Sr, Ba or Pb and B is Al or Fe and X may be S, As or P . Minerals in the beudantite mineral group form part of the -jarosite supergroup of minerals [3]. Minerals in this group are isostructural and extensive solid

solutions may form [4, 5]. For example woodhouseite and svanbergite SrAl3(PO4,SO4)2(OH)6 form solid solutions where these two minerals are the end members. The minerals are

_ 5 hexagonal and of point group D3d and space group ( R3m ) [6-8]. The mineral is colourless , white or flesh coloured and is associated with , and in the veins of an deposit at the Champion Mine [1]. The mineral is formed as a product of sulphatic argillic wall-rock alteration in hydrothermal vein and disseminated ore deposits [9, 10].

It is interesting that one of the products of the corrosion of bauxite is woodhouseite and the mineral may be found in bauxites. Woodhouseite is a mineral belonging to the beudantite subgroup of the alunite-jarosite supergroup [11, 12]. From a spectroscopic point of view, the mineral is most interesting because it contains both sulphate and phosphate anions together with OH units. Limited vibrational spectroscopic data is avaialble on this mineral [13, 14]. Previous studies by the authors on the Raman spectroscopy of alunites [15] and jarosites [16, 17] have been published. Breitinger et al. have published the Raman and infrared of

synthetic crandallites CaAl3(PO4)2(OH)5·H2O [18, 19].

Raman spectroscopy has proven very useful for the study of minerals [20-26]. Indeed Raman spectroscopy has proven most useful for the study of diagenetically related minerals as often occurs with minerals containing sulphate and phosphate groups, including woodhouseite

Ca,Al3(PO4,SO4)2(OH)6 , svanbergite SrAl3(PO4,SO4)2(OH)6 and hinsdalite

(Pb,Sr)Al3(PO4,SO4)2(OH)6. Raman spectroscopy is especially useful when the minerals are X-ray non-diffracting or poorly diffracting and very useful for the study of amorphous and colloidal minerals. This paper is a part of systematic studies of vibrational spectra of minerals of secondary origin in the oxide supergene zone. In this work we attribute bands at

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various wavenumbers to vibrational modes of woodhouseite using Raman spectroscopy complimented with infrared spectroscopy and relate the spectra to the structure of the mineral.

Experimental

Mineral

The mineral woodhouseite was supplied by The Mineralogical Research Company. The samples originated from Champion Mine, White Mountains, mono County, California [1]. The mineral is the ‘type’ mineral [1]. The mineral sample was confirmed by X-ray powder diffraction and the chemical analyses determined using an electron probe.

Raman spectroscopy

Crystals of woodhouseite were placed on a polished metal surface on the stage of an Olympus BHSM microscope, which is equipped with 10x, 20x, and 50x objectives. The microscope is part of a Renishaw 1000 Raman microscope system, which also includes a monochromator, a filter system and a CCD detector (1024 pixels). The Raman spectra were excited by a Spectra-Physics model 127 He-Ne laser producing highly polarised light at 633 nm and collected at a nominal resolution of 2 cm-1 and a precision of ± 1 cm-1 in the range between 100 and 4000 cm-1. Repeated acquisition on the crystals using the highest magnification (50x) was accumulated to improve the signal to noise ratio in the spectra. Spectra were calibrated using the 520.5 cm-1 line of a silicon wafer. Further details of the technique have been published [20-26].

A spectrum of woodhouseite was downloaded from the RRUFF data base [http://rruff.info/woodhouseite/display=default/]. The spectra have been placed in the supplementary information. The origin of the sample was also from Champion Mine, White Mountains, Mono County, California. The figures are labelled Figures S1 and S2.

Infrared spectroscopy

Infrared spectra were obtained using a Nicolet Nexus 870 FTIR spectrometer with a smart endurance single bounce diamond ATR cell. Spectra over the 4000525 cm-1 range were obtained by the co-addition of 64 scans with a resolution of 4 cm-1 and a mirror velocity of 0.6329 cm/s. Spectra were co-added to improve the signal to noise ratio.

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Band component analysis was undertaken using the Jandel ‘Peakfit’ (Erkrath, Germany) software package which enabled the type of fitting function to be selected and allowed specific parameters to be fixed or varied accordingly. Band fitting was done using a Lorentz-Gauss cross-product function with the minimum number of component bands used for the fitting process. The Lorentz-Gauss ratio was maintained at values greater than 0.7 and fitting was undertaken until reproducible results were obtained with squared correlations ( r2) greater than 0.995. Band fitting of the spectra is quite reliable providing there is some band separation or changes in the spectral profile.

RESULTS and DISCUSSION

Background

The mineral woodhouseite contains both sulphate and phosphate anions, and therefore, the presence of these anions can be observed using vibrational spectroscopy. A good starting point to study the position of the expected bands is to observe where the bands occur in aqueous solutions and then to observe the position of the bands resulting from the vibrational spectroscopy of minerals containing the individual anions. In aqueous systems, the sulphate -1 anion is of Td symmetry and has symmetric stretching mode (ν1) at 981 cm , the -1 antisymmetric stretching mode (ν3) at 1104 cm ,the symmetric bending mode (ν2) at -1 -1 451 cm and the ν4 mode at 613 cm [5]. In aqueous systems, Raman spectra of phosphate -1 oxyanions show a symmetric stretching mode (ν1) at 938 cm , the antisymmetric stretching -1 -1 mode (ν3) at 1017 cm , the symmetric bending mode (ν2) at 420 cm and the ν4 mode at 567 cm-1 [5]. The Raman spectroscopy of some phosphate minerals have been previously studied.

S.D. Ross in Farmer’s treatise [27] reported the infrared spectra of the jarosite-alunite minerals (Table 18.IX page 433). This table compares the infrared spectra of minerals from -1 the alunite-jarosite supergroups. Ross reported infrared bands for alunite at 1030 cm (ν1), -1 -1 -1 475 cm (ν2), 1086, 1170 cm (ν3), 605, 632 cm (ν4). OH vibrations were reported at 3485 and 505, 780, 802 cm-1 attributed to the stretching and bending of the OH units. Infrared -1 -1 -1 -1 bands for jarosite 1018, 1028 cm (ν1), 482 cm (ν2), 1100, 1190 cm (ν3), 638, 685 cm -1 (ν4). OH vibrations for jarosite were reported at 3260, 3355, 3430 and 512,790 cm attributed to the stretching and bending of the OH units. Raman spectra of these minerals

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have also been published [15, 16, 28, 29]. These results serve to show the positions of the bands which may be assigned to sulphate and phosphate.

SPECTROSCOPY The Raman spectrum of woodhouseite in the 950 to 1200 cm-1 region and the infrared spectrum in the 900 to 1300 cm-1 region are shown in Figures 1a and 1b. The Raman spectrum displays sharp bands which are well resolved in comparison of the infrared spectrum which consist of a broad spectral profile with a series of overlapping bands. The -1 Raman spectrum is characterised by an intense sharp band at 1028 cm assigned to the ν1 2- (SO4) symmetric stretching mode. The band is asymmetric on the high wavenumber side and a component band at 1032 cm-1 may be resolved. In the Raman spectrum of woodhouseite downloaded from the RRUFF web site and displayed in Figure S1, an intense Raman band at 1027 cm-1 is observed. Two overlapping Raman bands are found at 988 and -1 3- 1004 cm and these are assigned to the ν1 (PO4) symmetric stretching mode. In the Raman spectrum of woodhouseite downloaded from the RRUFF web site, two Raman bands are found at 972 and 985 cm-1. A low intensity peak may also be observed at around 1003 cm-1. The observation of two phosphate symmetric stretching modes suggests that there are two non-equivalent phosphate units in the structure of woodhouseite. In the infrared spectrum a -1 2- component band at 1023 cm may be resolved and this band is assigned to the ν1 (SO4) symmetric stretching mode. It is difficult to observe the position of the infrared bands which 3- may be attributed to the ν1 (PO4) symmetric stretching mode in the infrared spectrum. The infrared bands at 966 and 1000 cm-1 are possible peaks for this assignment.

The Raman spectrum of woodhouseite (Figure 1a) displays three low intensity Raman bands -1 3- 2- at 1096, 1151 and 1168 cm . These bands are assigned to the ν3 (PO4) and (SO4) antisymmetric stretching modes. In the Raman spectrum of woodhouseite downloaded from the RRUFF web site, Raman bands are found at 1095, 1160 and 1179 cm-1. It is probable that coupling occurs between these vibrational modes making it difficult to assign precisely the bands. These vibrational modes show much greater intensity in the infrared spectrum. Infrared bands are found at 1044, 1096, 1145, 1205 and 1224 cm-1.

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The Raman spectrum of woodhouseite in the 350 to 700 cm-1 region and the infrared spectrum in the 550 to 900 cm-1 region are shown in Figures 2a and 2b. This spectral region is where the sulphate and phosphate bending vibrations are observed. Multiple Raman bands -1 2- are found at 590, 618, 653 and 666 cm . These Raman bands are assigned to the 4 (SO4) bending modes. In the Raman spectrum of woodhouseite downloaded from the RRUFF web site (Figure S2), Raman bands are observed at 590, 616, 634 and 652 cm-1. For alunites, intense Raman band is observed at 655.3 cm-1 with a shoulder at 644.0 cm-1 for K-alunite, -1 -1 653.6 cm for Na-alunite, 655.1 cm for NH4-alunite. These bands are ascribed to the 4 bending modes of the sulphate anion [15]. The Raman spectra of the K and Na jarosites [16] in this spectral region show bands at around 575, 625 and 641 cm-1. The observation of multiple bands in this spectral region supports the concept of reduction in symmetry of the sulphate anion in these structures. In the infrared spectrum multiple bands are found. Infrared -1 bands are observed at 596, 621, 647and 660 cm . These bands are also ascribed to the 4 2- 2- (SO4) bending modes. The observation of multiple 4 (SO4) bands provides additional evidence for the reduction in symmetry of the sulphate anion in the woodhouseite structure.

-1 3- The Raman band at 534 cm is assigned to the triply degenerate 4 (PO4) bending modes. In the Raman spectrum of woodhouseite downloaded from the RRUFF web site, an intense band is found at 533 cm-1. This band does have a shoulder at 527 cm-1. It is possible that the -1 2- Raman bands at 475 and 485 cm are attributable to the doubly degenerate 2 (SO4) bending modes. In the Raman spectrum of woodhouseite downloaded from the RRUFF web site, Raman bands are denoted at 478 and 485 cm-1. The two sets of bands are in close agreement. The assignment of these bands is supported by the position of bands in the alunite Raman spectrum. In the Raman spectrum of alunites bands are observed for K-alunite at 482, 488 -1 -1 -1 and 505 cm ; for Na-alunite at 486 and 517 cm and for NH4-alunite at 487 and 508 cm [15]. It is possible that the two Raman bands at 364 and 408 cm-1 are assignable to the 3- doubly degenerate 2 (PO4) bending modes. In the Raman spectrum of woodhouseite downloaded from the RRUFF web site, Raman bands were observed at 363 and 406 cm-1.

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In the infrared spectrum bands below 550 cm-1 are not observed as the bands occur at positions below the limit of the ATR instrumentation. In the infrared spectrum intense bands are observed at 725 and 761 cm-1. These bands may be assigned to AlO stretching vibrations. Bands in these positions have been observed for crandallite [18, 19]. The bands were assigned to Al2OH and AlO2(OH)4 stretching vibrations. Two infrared bands are observed at 855 and 880 cm-1. Bands in these positions were not found in the Raman spectrum. One

likely assignment is that these bands are due to the stretching vibration of (O3POH) units. Infrared bands were observed in similar positions in the vibrational spectra of crandallite [18, 19].

The Raman spectrum in the far low wavenumber region is reported in Figure 3. An intense band is observed at 249 cm-1. An intense band for jarosite was also found at around 230 cm-1. It may be attributed to OH.....H hydrogen bond vibrations. In the Raman spectrum of woodhouseite downloaded from the RRUFF web site, very intense bands were observed at 178 and 247 cm-1.

The Raman spectrum of woodhouseite in the 2800 to 3600 cm-1 region and the infrared spectrum in the 2400 to 3800 cm-1 region are shown in Figures 4a and 4b. The Raman spectrum of woodhouseite show two features centred upon 3122 and 3460 cm-1. The two bands found at 3401 and 3460 cm-1 are assigned to the OH stretching vibrations of OH units involved in hydrogen bonding. In the infrared spectrum two bands were observed at 3401 and -1 3465 cm and are attributed to OH stretching vibrations of the Al2OH units. Broad bands are observed in the Raman spectrum of woodhouseite at 3001 and 3122 cm-1. These bands are

assigned to hydrogen bonded (O3POH) units. This assignment is also given to the infrared bands at 2922 and 3019 cm-1.

Low intensity bands are observed in both the Raman and infrared spectra (Figures 5a and 5b). The assignment of these bands is not known but a distinct possibility is that the bands are due to overtone or combination bands. The lack of a Raman or infrared band at around 1630 cm-1 is significant because it means the absence of water in the mineral structure.

If we use a Libowitzky type empirical equation, [30] and we assume that we can use infrared data in the equation, estimates of the hydrogen bond distances can be obtained. Studies have shown a strong correlation between OH stretching frequencies and both O…O bond distances and H…O hydrogen bond distances [31-34]. Libowitzky showed that a regression function

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can be employed relating the hydroxyl stretching wavenumbers with regression coefficients

better than 0.96 using infrared spectroscopy [35]. The function is described as: ν1 =

d (OO) (3592  304) 109 0.1321 cm-1. Thus O---O bond distances may be calculated using this Libowitzky empirical function. The values for the OH stretching vibrations for the OH units give calculated approximate O-H...O hydrogen bond lengths of 2.92 and 3.1 Å. These values suggest that the hydroxyl units are only weakly hydrogen bonding to the adjacent sulphate or phosphate units as mentioned. The approximate O-H...O hydrogen bond lengths calculated for the OH stretching vibrations are 2.65 Å (3001 cm-1), 2.68 Å (3122 cm-1), 2.80 Å (3401 cm-1) and 2.85 Å (3460 cm-1).Thus OH units with different hydrogen bond distances are found in the woodhouseite structure. These results suggest that the OH units are involved in hydrogen bonding to varying strengths according to their position in the woodhouseite structure. Significantly some OH units are more strongly hydrogen bonded than the OH

units. These are due to the bands assigned to the O3POH units.

Variation in the hydrogen bond distance of jarosites for the 3411 cm-1 band was found to be between 2.760 and 2.867 Å. The variation for the 3292 cm-1 band is between 2.678 and 2.857 Å. In contrast the variation in hydrogen bond distance for the 3388 cm-1 band of the natural K-jarosite is between 2.778 and 2.796 Å and for the 3357 cm-1 band is between 2.764 and 2.778 Å.

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Conclusions

Bands associated with phosphate and sulphate vibration modes dominate the Raman and infrared spectra of woodhouseite. The majority of the Raman and infrared bands were

assigned to the symmetric stretching modes (ν1), the antisymmetric stretching modes (ν3), the

symmetric bending modes (ν2), and the ν4 bending modes of phosphate and sulfate. A comparison is made with the spectra of alunites. The most intense modes in the Raman spectrum are the symmetric stretching modes of phosphate and sulphate. Two symmetric stretching modes for both phosphate and sulphate support the concept of non-equivalent phosphate and sulphate units in the woodhouseite structure. Bands in the OH stretching region enabled the hydrogen bond distances to be calculated. Comparison of the hydrogen bond distances and the calculated hydrogen bond distances from the structure models indicates that hydrogen bonding in woodhouseite occurs between the two OH units rather

2- than OH to SO4 units.

Acknowledgements

The financial and infra-structure support of the Chemistry Discipline of the Faculty of Science and Technology, Queensland University of Technology is gratefully acknowledged. The Australian Research Council (ARC) is thanked for funding the instrumentation.

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References

[1] J.W. Anthony, R.A. Bideaux, K.W. Bladh, M.C. Nichols, Handbook of Mineralogy Vol.IV. Arsenates, phosphates, vanadates - Mineral Data Publishing, Tucson, Arizona, Mineral data Publishing, Tucson, Arizona, 2000. [2] D.W. Lemmon, A. Rautenberg, Woodhouseite, a new mineral of the beudantite group, American Mineralogist, 22 (1937) 939-948. [3] E. Sato, I. Nakai, R. Miyawaki, S. Matsubara, Crystal structures of alunite family minerals: beaverite, corkite, alunite, natroalunite, jarosite, svanbergite, and woodhouseite, Neues Jahrbuch fuer Mineralogie, Abhandlungen, 185 (2009) 313-322. [4] A. Kunov, Convergence of minerals with an alunite-type structure (phosphates, phosphates-sulfates, and sulfates): some cases from Bulgaria, Geologica Balcanica, 29 (1999) 71-79. [5] W.S. Wise, Solid solution between the alunite, woodhouseite, and crandallite mineral series, Neues Jahrbuch fuer Mineralogie, Monatshefte, (1975) 540-545. [6] T. Kato, Crystal structures of goyazite and woodhouseite, Neues Jahrbuch fuer Mineralogie, Monatshefte, (1971) 241-247. [7] T. Kato, Further refinement of the woodhouseite structure, Neues Jahrbuch fuer Mineralogie, Monatshefte, (1977) 54-58. [8] T. Kato, Y. Miura, The crystal structures of jarosite and svanbergite, Mineralogical Journal, 8 (1977) 419-430. [9] G. Pe-Piper, L.M. Dolansky, Early diagenetic origin of Al phosphate-sulfate minerals (woodhouseite and crandallite series) in terrestrial sandstones, Nova Scotia, Canada, American Mineralogist, 90 (2005) 1434-1441. [10] G. Pe-Piper, L.M. Dolansky, Early diagenetic origin of Al phosphate-sulfate minerals (woodhouseite and crandallite series) in terrestrial sandstones, Nova Scotia, Canada. [Erratum to document cited in CA143:408394], American Mineralogist, 91 (2006) 226-228. [11] S. Gaboreau, D. Beaufort, P. Vieillard, P. Patrier, P. Bruneton, Aluminum phosphate- sulfate minerals associated with the Proterozoic unconformity-type uranium deposits in the East Alligator River Uranium Field, Northern Territories, Australia, Can. Mineral., 43 (2005) 813-827.

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[12] S. Gaboreau, M. Cuney, D. Quirt, D. Beaufort, P. Patrier, R. Mathieu, Significance of aluminum phosphate-sulfate minerals associated with U unconformity-type deposits: the Athabasca basin, Canada, Am. Mineral., 92 (2007) 267-280. [13] E.I. Nikitina, V.I. Sotnikov, G.A. Golubova, Infrared absorption spectra of minerals of the woodhouseite-svanbergite series, Geol. Geofiz., (1968) 114-118. [14] S.V. Gevorkyan, A.A. Petrunina, A.S. Povarennykh, IR spectroscopic and x-ray diffraction study of crandallite-group minerals, Konst. Svoistva Miner., 10 (1976) 51-59. [15] R.L. Frost, R.-A. Wills, M.L. Weier, W. Martens, J.T. Kloprogge, A Raman spectroscopic study of alunites, Journal of Molecular Structure, 785 (2006) 123-132. [16] R.L. Frost, R.-A. Wills, M.L. Weier, W. Martens, S. Mills, A Raman spectroscopic study of selected natural jarosites, Spectrochimica Acta, Part A: Molecular and Biomolecular Spectroscopy, 63A (2006) 1-8. [17] R.L. Frost, R.-A. Wills, W. Martens, Raman spectroscopy of beaverite and plumbojarosite, Journal of Raman Spectroscopy, 36 (2005) 1106-1112. [18] D.K. Breitinger, G. Brehm, J. Mohr, D. Colognesi, S.F. Parker, A. Stolle, T.H. Pimpl, R.G. Schwab, Vibrational spectra of synthetic crandallite-type minerals - optical and inelastic neutron scattering spectra, Journal of Raman Spectroscopy, 37 (2006) 208-216. [19] D.K. Breitinger, R. Krieglstein, A. Bogner, R.G. Schwab, T.H. Pimpl, J. Mohr, H. Schukow, Vibrational spectra of synthetic minerals of the alunite and crandallite type, Journal of Molecular Structure, 408-409 (1997) 287-290. [20] R.L. Frost, S. Bahfenne, Raman spectroscopic study of the antimonate mineral bahianite Al5Sb35+O14(OH)2, J. Raman Spectrosc., 41 (2010) 207-211. [21] R.L. Frost, S. Bahfenne, Raman spectroscopic study of the arsenite minerals leiteite ZnAs2O4, reinerite Zn3(AsO3)2 and cafarsite Ca5(Ti,Fe,Mn)7(AsO3)12·4H2O, J. Raman Spectrosc., 41 (2010) 325-328. [22] R.L. Frost, S. Bahfenne, J. Cejka, J. Sejkora, S.J. Palmer, R. Skoda, Raman microscopy of haidingerite Ca(AsO3OH)·H2O and brassite Mg(AsO3OH)·4H2O, J. Raman Spectrosc., 41 (2010) 690-693. [23] R.L. Frost, S. Bahfenne, J. Cejka, J. Sejkora, J. Plasil, S.J. Palmer, Raman and infrared study of phyllosilicates containing heavy metals (Sb, Bi): bismutoferrite and chapmanite, J. Raman Spectrosc., 41 (2010) 814-819.

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[24] R.L. Frost, K.H. Bakon, S.J. Palmer, Raman spectroscopic study of synthetic reevesite and cobalt substituted reevesite (Ni,Co)6Fe2(OH)16(CO3)·4H2O, J. Raman Spectrosc., 41 (2010) 78-83. [25] R.L. Frost, J. Cejka, J. Sejkora, J. Plasil, S. Bahfenne, S.J. Palmer, Raman spectroscopy of the basic copper arsenate mineral: euchroite, J. Raman Spectrosc., 41 (2010) 571-575. [26] R.L. Frost, J. Cejka, J. Sejkora, J. Plasil, S. Bahfenne, S.J. Palmer, Raman microscopy of the mixite mineral BiCu6(AsO4)3(OH)6·3H2O from the Czech Republic, J. Raman Spectrosc., 41 (2010) 566-570. [27] V.C. Farmer, Mineralogical Society Monograph 4: The Infrared Spectra of Minerals, 1974. [28] R.L. Frost, R.-A. Wills, M.L. Weier, W. Martens, Comparison of the Raman spectra of natural and synthetic K- and Na-jarosites at 298 and 77 K, Journal of Raman Spectroscopy, 36 (2005) 435-444. [29] R.L. Frost, D.L. Wain, Near-infrared spectroscopy of natural alunites, Spectrochimica Acta, Part A: Molecular and Biomolecular Spectroscopy, 71 (2008) 490-495. [30] E. Libowitzky, Correlation of O-H stretching frequencies and O-H...O hydrogen bond lengths in minerals, Monatsh. Chem., 130 (1999) 1047-1059. [31] J. Emsley, Very strong hydrogen bonding., Chemical Society Reviews, 9 (1980) 91-124. [32] H. Lutz, Hydroxide ions in condensed materials - correlation of spectroscopic and structural data., Structure and Bonding (Berlin, Germany), 82 (1995) 85-103. [33] W. Mikenda, Stretching frequency versus bond distance correlation of O-D(H)...Y (Y = N, O, S, Se, Cl, Br, I) hydrogen bonds in solid hydrates., Journal of Molecular Structure, 147 (1986) 1-15. [34] A. Novak, Hydrogen bonding in solids. Correlation of spectroscopic and crystallographic data., Structure and Bonding (Berlin), 18 (1974) 177-216. [35] E. Libowitsky, Correlation of the O-H stretching ferequencies and the O-H...H hydrogen bond lengths in minerals, Monatschefte fÜr chemie, 130 (1999) 1047-1049.

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List of Figures

Figure 1a Raman spectrum of woodhouseite in the 950 to 1200 cm-1 region.

Figure 1b Infrared spectrum of woodhouseite in the 900 to 1300 cm-1 region.

Figure 2a Raman spectrum of woodhouseite in the 350 to 700 cm-1 region.

Figure 2b Infrared spectrum of woodhouseite in the 550 to 900 cm-1 region.

Figure 3 Raman spectrum of woodhouseite in the 100 to 350 cm-1 region.

Figure 4a Raman spectrum of woodhouseite in the 2800 to 3600 cm-1 region.

Figure 4b Infrared spectrum of woodhouseite in the 2400 to 3800 cm-1 region.

Figure 5a Raman spectrum of woodhouseite in the 1650 to 1900 cm-1 region.

Figure 5b Infrared spectrum of woodhouseite in the 1550 to 1850 cm-1 region.

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Figure 1a Figure 1b

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Figure 2a Figure 2b

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Figure 3

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Figure 4a Figure 4b

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Figure 5a Figure 5b

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