Title The crystal structure and composition of pottsite, (Pb3xBi4-2x)(VO4)4·H2O (0.8 < x < 1.0)
Authors Kovrugin, VM; Siidra, OI; Zaitsev, AN; Spratt, J; Shilovskikh, V; Agakhanov, AA; Turner, R
Date Submitted 2016-04-04 1 Title: The Composition and Crystal Structure of Pottsite, (Pb3xBi4–3x)Bix(VO4)4∙H2O или (Pb3xBi4– 2 2x)(VO4)4∙H2O, 0.8 < x < 1.0 and a Comparison with Related Vanadate Minerals Based on 5+ 3 Isolated V O4 Tetrahedra 4 5 Running title: The crystal structure of pottsite 6 7 Plan of the article: 8 Abstract 9 1. Introduction 10 2. Experimental procedure 11 2.1. Chemical composition 12 2.2. Single crystal X-ray diffraction 13 3. Results 14 3.1 Cation coordination 15 3.2 Structure description 16 4. Discussion 17 Acknowledgements 18 References 19
20 Corresponding author: Oleg I. Siidra
21 E-mail address: [email protected]
22 Mailing address: Department of Crystallography, St. Petersburg State University, University emb. 23 7/9, 199034 St. Petersburg, Russia 24
25
Kovrugin V.M. et al. 1 26
27 The Composition and Crystal Structure of Pottsite, 28 (Pb3xBi4–3x)Bix(VO4)4∙H2O, 0.8 < x < 1.0 and a 29 Comparison with Related Vanadate Minerals based 5+ 30 on Isolated V O4 Tetrahedra 31
1 1, 2,3 32 VADIM M. KOVRUGIN , OLEG I. SIIDRA *, ANATOLY N. ZAITSEV , 3 4 5 33 JOHN SPRATT , VLADIMIR SHILOVSKIKH AND RICK W. TURNER 34 35 1 Department of Crystallography, St. Petersburg State University, University emb. 7/9, 199034 St. 36 Petersburg, Russia 37 2 Department of Mineralogy, St. Petersburg State University, University emb. 7/9, 199034 St. 38 Petersburg, Russia 39 3 Department of Earth Sciences, Natural History Museum, Cromwell Road, London, SW7 5BD, UK 40 4 Geomodel Centre, St. Petersburg State University, University emb. 7/9, 198504 St. Petersburg, 41 Russia 42 5 The Drey, Allington Track, Allington, Salisbury SP4 0DD, Wiltshire, United Kingdom 43
44 E-mail address: [email protected]
45
46
Kovrugin V.M. et al. 2 47 Abstract:
48 Pottsite from the Linka mine (Nevada, USA) has been studied by scanning electron 49 microscopy, energy- and wavelength-dispersive analyses, and a single crystal analysis. The formula 50 of pottsite, calculated on the basis of (V+As) = 4, shows that the Pb/Bi atomic ratio in pottsite 51 varies between 0.86 and 1.48, and a plot of Pb vs Bi (atoms per formula unit) suggests elemental 52 substitution follows the rule 3Pb2+ 2Bi3+. Analyses with the low Pb/Bi atomic ratio (0.86-1.01) 53 are close to the pottsite formula derived from the single-crystal X-ray diffraction
54 (Pb2.45Bi1.55)Bi0.82(VO4)4.00∙H2O. Pottsite crystallizes in the tetragonal space group I41/a, 55 a = 11.0839(5)Å, c = 12.6516(6) Å, V = 1554.29(16) Å3, Z = 1. Crystal structure was solved by
56 direct methods and refined to R1 = 0.034 (wR2 = 0.063) for 1167 unique reflections with F>4σF. The 57 structure contains one A site split into low occupancy A(1) and A(2) sites. The A(1) site has an 2+ 58 occupancy of Pb0.542Bi0.388, whereas A(2) is occupied by Pb cations only, with site occupation of
59 Pb0.07. The Bi(1) site has a site occupation factor of 0.76 and forms a distorted but symmetrical 60 square antiprismatic coordination environment, which indicates a low degree of stereochemical 61 activity of the lone electron pair on Bi3+. The symmetrically independent V(1) site belongs to a V5+
62 cation which is coordinated by four oxygen atoms to form a distorted VO4 tetrahedron.
63 The atomic arrangement in the structure of pottsite can be described as the packing of 5+ 64 isolated V O4 tetrahedra, linked with heavy cations via common oxygen atoms to 2D blocks or 65 double-layered (DL) structural units that are parallel to (001). DL units are formed by pairs of 66 vanadate tetrahedra arranged opposite one to each other and oriented in opposite directions. Water 3– 67 molecules are located in between vanadate tetrahedral groups to form [(VO)4(H2O)] chains that 68 are separated from adjacent chains in the (001) plane by rows of Pb2+and Bi3+ cations extended in 69 the [120] direction. Two adjacent DL units are shifted one relative to other by translation of ±1/2 70 unit along the b axis, with an interlayer spacing of about 1.13 Å, measured as the shortest distance
71 between adjacent O–O edges of the VO4 tetrahedra. Comparison of pottsite with related vanadate 5+ 72 minerals based on isolated V O4 tetrahedra with formation of DL units is given.
73 Observed variations in contents of Pb and Bi and data from the single-crystal X-ray
74 diffraction suggest a general formula of pottsite as (Pb3xBi4–2x)(VO4)4∙H2O, 0.8 < x < 1.0, and an
75 ideal mineral formula of (Pb3Bi)Bi(VO4)4∙H2O.
76
77 Keywords: pottsite, crystal structure, vanadate minerals, lead, bismuth, oxidized zone, Linka Mine
78
Kovrugin V.M. et al. 3 79
80 1. Introduction
81 Pottsite is a rare mineral first described by Williams S.A. (1988) (Williams, 1988) from the oxidized 82 zone of the Linka tungsten Mine northwest of Potts, Lander County, Nevada, USA. The mine 83 contains a disseminated tungsten (scheelite) and molybdenum orebody, associated with tactites 84 formed by the metamorphism of existing carbonate sediments by the nearby intrusion of 85 granodiorite. A later event emplaced quartz, which contains disseminated grains of chalcopyrite and 86 the rare Cu-Pb-Bi sulphosalt mineral junoite. Subsequent oxidation converted junoite successively 87 to bismutite, then to an unknown orange bismuth vanadate, and finally to clinobisvanite, with 88 pottsite forming instead of clinobisvanite in a few cases. Other minerals associated with this 89 assemblage are vanadinite, powellite replacing molybdenite, chrysocolla, an unknown copper 90 vanadate, and a range of unidentified vanadate phases coating altered scheelite grains.
91 Pottsite was assumed to be a vanadate of Pb2+ and Bi3+ with the chemical formula of
92 HPbBi(VO4)2∙2H2O obtained by microprobe analysis. Hydrogen was added to the formula to 93 provide charge balance only. However, water content was determined by the Penfield method. 94 Pottsite was also studied later by IR and Raman spectroscopy (Frost et al., 2006). Williams S.A.
95 (1988) reported tetragonal symmetry for pottsite (I4122, a = 11.084 Å, c = 12.634 Å) evaluated 96 from powder X-ray diffraction data. However, single crystal measurements were not performed and 97 the crystal structure of pottsite remained unknown. Here, we report the result of the crystal structure
98 determination of pottsite, and a comparison of VO4 tetrahedra packing in related vanadate minerals.
99 2. Experimental procedure
100 The sample used in this investigation was from material collected at the Linka Mine in the late 101 1990’s by the American mineral collector, Brent Thorne, who kindly provided the sample used for 102 analysis.
103
104 2.1 Chemical composition
105 The composition of the pottsite from the Linka mine was determined by both energy- and 106 wavelength-dispersive analyses (EDS and WDS resectively). EDS analyses were obtained using a 107 Hitachi S-3400N scanning electron microscope equipped with an Oxford Instruments X-Max 20
Kovrugin V.M. et al. 4 108 Energy Dispersive Spectrometer (St. Petersburg State University). The electron beam accelerating 109 voltage was 20 kV and the current 2.5 nA, both focused and defocused beam (5×5 to 10×5 µm spot 110 size) were used and X-ray acquisition time was 30 seconds. System calibration was performed on
111 Co. The following standards were used CaSO4 (for Ca), V (for V), InAs (for As), Pb (for Pb) and Bi 112 (for Bi). WDS analyses were obtained using a Cameca SX-100 electron microprobe (Natural 113 History Museum). Instrument conditions used were: kV = 15, I = 20 nA and spot size = 1µm. The 114 standards used were as follows: topaz (for F), NaCl (for Cl), vanadinite (for V and Pb), Bi (for Bi), 115 wollastonite (for Ca) and GaAs for (As). Correction for peak overlaps (Pb / Cl and Pb / Bi) were 116 applied from empirical measurements taken from standards (PbS) and were applied within software
117 prior to matrix correction. H2O was assumed by difference initially for matrix correction and then 118 post matrix correction calculated by stochiometery. Only WDS analyses were used in discussion of 119 pottsite composition below.
120 The two analyzed pottsite crystals (Figure 1S) are heterogeneous in composition and show wide
121 variations in content of lead and bismuth (32.7-43.9 wt.% PbO and 30.7-39.9 wt.% Bi2O3), but
122 nearly constant vanadium (23.7-25.0 wt.% V2O5) (Tables 1, 1S, Fgure 1S). Minor components are
123 calcium (up to 1.3 wt.% CaO), arsenic (up to 1.2 wt.% As2O5) and chlorine (up to 0.3 wt.% Cl). 124 Mineral formulae, calculated on the basis of (V+As) = 4 atoms per formula unit (apfu), show that 125 the Pb/Bi atomic ratio in pottsite varies between 0.86 and 1.48 and a plot of Pb vs Bi (apfu) 126 suggests that elemental substitution is 3Pb2+ 2Bi3+ (Figure 1) or more correctly 3(Pb2+ + Ca2+) 127 2Bi3+. Figure 1 also shows two groups of pottsite with different composition: one with low Pb/Bi 128 atomic ratio (0.86-1.01) and another with high Pb/Bi ratio (1.22-1.48). Average composition of the
129 pottsite with the low Pb/Bi ratio ((Pb2.27 Ca0.26Bi2.37)((VO4)3.94)(AsO4)0.06)Cl0.05∙H2O) is close to the
130 mineral formula derived from the single-crystal X-ray diffraction (Pb2.45Bi2.37)(VO4)4.00∙H2O (see 131 below). This variety of the mineral is characterized by presence of minor chlorine while the element 132 content is always below detection limit in pottsite with high Pb/Bi ratio (Table 1). Observed
133 variations in contents of Pb and Bi suggest a general formula of pottsite as (Pb3xBi4–2x)(VO4)4∙H2O,
134 0.8 < x < 1.0 and an ideal mineral formula is (Pb3Bi)Bi(VO4)4∙H2O. The latter requires (wt.%) PbO
135 44.13, Bi2O3 30.71, V2O5 23.97, H2O 1.19, total 100.00.
136 The new compositional data for the pottsite from the Linka mine show some differences to 137 compositions given in the first description of the mineral by Williams (1988); the pottsite studied in 138 this work is particularly characterized by higher lead, and lower water contents (Table 1).
139 Recalculation of the average analysis from Williams (1988) with one molecule H2O gives a low 140 analytical total and excess negative charge of 2.02. This probably indicates an incorrect analytical 141 protocol for the original microprobe analysis [which was not described in Williams (1988)] and the
Kovrugin V.M. et al. 5 142 presence of micro-inclusions of H2O-bearing mineral(s) in the pottsite fraction analysed by the 143 Penfield method. Unidentified vanadate phases are known to coat fracture surfaces in scheelite at 144 this locality and are likely to be generally present in the analysed material by Williams (1988).
145 Overall, we suggest that the composition of pottsite from the Linka mine is highly variable due 146 to lead-bismuth substitution and the gross Pb/Bi ratio observed in any particular specimen likely 147 therefore depends on the exact collecting point at the mine, but zoning effects can also be seen to be 148 present within individual crystals (Figure 1).
149
150 2.2 Single crystal X-ray diffraction
151 Single crystal X-ray analysis of pottsite was carried out using a Bruker SMART diffractometer
152 equipped with an APEX II CCD detector operated with MoKα radiation at 50 kV and 40 mA. A 153 single yellow translucent block-shaped crystal with dimensions of 0.18×0.16×0.12 mm was chosen 154 for X-ray diffraction data. More than a hemisphere of the data were collected with the frame width 155 of 0.5º in ω, and 60 s spent counting for each frame. The data were integrated and corrected for 156 absorption using a multi-scan type model using the Bruker programs APEX and SADABS.
157 The mineral is tetragonal, space group I41/a, a = 11.0839(5) Å, c = 12.6516(6) Å, 3 158 V = 1554.29(16) Å , Z = 1. The unit cell parameters are very close to those (I4122, a = 11.084, c = 159 12.634 Å,) determined in (Williams, 1988) by powder X-ray diffraction.
160 The crystal structure was solved by direct methods and refined to R1 = 0.034 (wR2 = 0.063) for
161 1167 reflections with F>4σF using the SHELX program package (Sheldrick, 2008). Positions of 162 hydrogen atoms were not localized. All atoms, except one oxygen atom assigned as a water 163 molecule, were refined anisotropically. Refinement of the occupancies lead to an electroneutral
164 formula (Pb2.448Bi1.552)Bi0.816(VO4)4∙H2O. It was decided not to fit the formula obtained by 165 structural studies completely with chemical analyses due to reasons discussed above. Minor 166 amounts of Ca2+ observed by the chemical analyses were neglected during the process of 167 refinement. We suggest Ca substitutes for Pb in either the A(1) or A(2) sites in the structure of 168 pottsite, while As invariably substitutes for vanadium in the V(1) site. The details of the crystal 169 data, X-ray data collection, and the structure refinement are given in Table 2. The final fractional 170 coordinates, site occupation factors (SOF) and displacement parameters of atoms are given in 171 Tables 3 and 4. Selected interatomic distances are listed in Table 5. The result of the bond valence 172 sum (BVS) calculations for pottsite are given in Table 6. Empirical bond valence parameters 173 required for the BVS calculations for Bi3+, Pb2+ and V5+ were taken from (Krivovichev, 2012),
Kovrugin V.M. et al. 6 174 (Krivovichev & Brown, 2001), and (Brese & O’Keeffe, 1991), respectively. The BVS for the A(1) 175 site demonstrates a deviation from theoretical values of 2+ or 3+ expected for fully occupied site 176 but not observed for a mixed A(1) site. Similar calculated BVS of mixed Pb/Bi sites were recently 177 observed e.g. in the series of novel synthetic Pb/Bi oxychlorides (Aliev et al., 2013; Lü et al., 3+,2+ 178 2014), and in the crystal structure of brendelite, (Bi,Pb)2Fe O2(PO4)(OH) (Krause et al., 1998).
179 Further details of the crystal structure investigation are available from the 180 Fachinformationszentrum Karlsruhe, D-76344 Eggenstein-Leopoldshafen, Germany, on quoting the 181 depository number CSD–429503, the names of the authors and the citation of the paper.
182 3. Results
183 3.1 Cation coordination
184 The crystal structure of pottsite contains one fully occupied V(1) site, one mixed A site which is 185 split into A(1) and A(2) sites, one low occupancy Bi(1) site, and five oxygen anion sites.
186 The V(1) site belongs to a V5+ cation which is coordinated by four oxygen atoms to form a
187 distorted VO4 tetrahedron (Fig. 3a) with one short V(1)–O(4) bond of 1.687 Å. The average
191 crystal structures of desclozite, PbZn(VO4)(OH) (Hawthorne & Faggiani, 1979), brackebuschite,
192 Pb2Mn(VO4)2(OH) (Donaldson & Barnes, 1955; Foley & Hughes, 1997), schubnelite, FeVO4(H2O)
193 (Cesbron, 1970; Schindler & Hawthorne, 1999), and turanite, Cu5(VO4)2(OH)4 (Sokolova et al., 194 2004). BVS calculations demonstrate valence value of 5.06 vu for V(1) (Table 6).
195 There is one A site (A = Pb, Bi) in the crystal structure of pottsite which is split into A(1) and 196 A(2) sites. Analysis of the BVS calculations for the A(1) site (2.30 vu or 2.43 vu calculated for Pb2+ 197 or Bi3+, respectively) confirms mixed occupancy with the ratio of Pb:Bi as 0.612:0.388 as refined. 198 The A(1)–A(2) distance is 0.476 Å. The bond valence sum at A(2) site is 2.03 vu, which is consistent 2+ 199 with the formal valence of Pb . Final A site occupancies are Pb0.542Bi0.388 and Pb0.070 for A(1) and 200 A(2) respectively, which are consistent with the electroneutral formula of pottsite. A(1) and A(2) 201 sites are similarly coordinated in strongly irregular fashion (Fig. 3b). All A–O (A = Pb, Bi) distances 202 ≤ 3.5 Å were taken into consideration in the structure of pottsite. Large Pb2+ and Bi3+ cations form 203 five short (2.311–2.737 Å) and strong (0.50–0.21 vu) bonds in one coordination hemisphere and
Kovrugin V.M. et al. 7 204 three long (2.810–3.280 Å) weaker (0.18–0.07 vu) bonds in another. This irregular coordination of 205 Pb2+ and Bi3+ is due to the stereochemical activity of the lone electron pair.
206 The crystal structure of pottsite also contains one low-occupancy Bi(1) site with a distorted 207 square antiprismatic coordination environment (Fig. 3c). The coordination is rather symmetrical, 208 which indicates a low degree of stereochemical activity of the lone electron pair on the Bi3+. A
209 similar phenomenon was reported also in the crystal structures of beyerite, CaBi2(CO3)2O2 (Grice,
210 2002), and bismutite, Bi2(CO3)O2 (Grice, 2002). The average
215 The Ow atom is located at a distance of 2.810 Å from A(2) and 3.280 Å from A(1) and was
216 assigned on the basis of BVS calculations to an H2O molecule (Table 6). The geometrical
217 environment of the Ow site is illustrated in Fig. 3d.
218 3.2 Structure description
219 The atomic arrangement in the structure of pottsite can be described as the packing of isolated 5+ 220 V O4 tetrahedra linked with heavy cations, via common oxygen atoms, to 2D blocks or double- 221 layered (DL) structural units that are parallel to (001) (Fig. 4). DL units are formed by pairs of 222 vanadate tetrahedra arranged opposite to each other and oriented in opposite directions. DL units 223 have a height of a half of the c parameter value in the structure of pottsite. Groups of four isolated
224 VO4 tetrahedra extend along the [120] direction (Fig. 5). Water molecules are located in between 3– 225 vanadate tetrahedral groups to form [(VO)4(H2O)] chains separated from each other in the (001) 226 plane by rows of Pb2+, Bi3+ cations extended in the same [120] direction (Fig. 5). Two adjacent DL 227 units are shifted one relative to other by ±1/2 unit translation along the b axis with an interlayer
228 spacing of about 1.13 Å, measured as the shortest distance between adjacent O–O edges of the VO4 229 tetrahedra (Fig. 4).
230 4. Discussion
231 There are a number of vanadate minerals based on DL units similar to those observed in pottsite. 232 Geometrical parameters of these minerals are listed in Table 7. Fig. 6 shows projections of the DL 233 units in the structures of these minerals. DL1 packing of the vanadate tetrahedra shown in Fig. 5 3+ 234 dominates. It was observed in the following mineral structures: brackebuschite Pb2Mn (VO4)2(OH)
Kovrugin V.M. et al. 8 235 (Donaldson & Barnes, 1955; Foley & Hughes, 1997), bushmakinite Pb2Al(PO4)(VO4)(OH) (Pekov 3+ 236 et al., 2002; Yakubovich et al., 2002), calderónite Pb2Fe (VO4)2(OH) (Del Tanago et al., 2003), 3+ 237 gamagarite Ba2Fe (VO4)2(OH) (de Villers, 1943; Harlow & Dunn, 1984; Basso et al., 1987), 3+ 3+ 238 krettnichite PbMn 2(VO4)2(OH)2 (Brugger et al., 2001), mounanaite PbFe 2(VO4)2(OH)2 (Cesbron
239 & Fritsche, 1969; Werner Krause et al., 1998), gurimite Ba3(VO4)2 (Süsse & Buerger, 1970;
240 Mugavero et al., 2008) and vesignieite Cu3Ba(VO4)2(OH)2 (Guillemin, 1955; Zhesheng et al., 2+ 241 2009). VO4 tetrahedra are arranged in a hexagonal manner in an “edge-to-edge” fashion, with Pb 242 or Ba2+ cations located in the centres of the hexagonal rings.
243 Vanadate tetrahedra also form hexagonal rings, in the crystal structure of averievite,
244 Cu5O2(VO4)2∙CuCl2 (Starova et al., 1997; Vergasova et al., 1998) but here the tetrahedra are packed 245 in a “vertex-to-vertex” fashion with wide channels occupied by linear Cu2+–Cl– groups (Fig. 5, 246 DL2).
247 The DL units are also in “vertex-to-vertex” fashion in the structure of schubnelite, Fe(VO4)∙H2O 248 (Cesbron, 1970; Schindler & Hawthorne, 1999) (Fig. 5, DL3). Water molecules and Fe3+ cations fill 249 the internal spacing of the DL3 units.
250 The arrangement of the vanadate tetrahedra observed in the structures of hechtsbergite,
251 Bi2O(VO4)(OH) (Krause et al., 1997; Uehara & Shirose, 2013), and namibite, Cu(BiO)2(VO4)(OH) 252 (von Knorring & Sahama, 1981; Kolitsch & Giester, 2000; Kolitsch & Götzinger, 2000; Uehara & 253 Shirose, 2013) is very similar (Fig. 5, DL4,5). The DL5 vanadate unit of the latter has shorter height 254 and no internal chemical species, while Bi3+ cations are incorporated into corrugated DL4 units in 255 the structure of hechtsbergite.
10+ 256 Oxocentered tetrahedral [O9Pb14] layers (Krivovichev et al., 2013) contain double square
257 vacancies occupied by isolated VO4 tetrahedra in the crystal structure of kombatite,
258 Pb14O9(VO4)2Cl4, (Rouse et al., 1986; Cooper & Hawthorne, 1994). This arrangement of vanadate 259 tetrahedra can be also considered as DL6 units according to the proposed description of structural 260 architectures in this work.
261 Finally, the DL7 unit was observed in structure of pottsite. Such an arrangement of vanadate 262 tetrahedra has no similarity in any related mineral. Nevertheless, all the minerals mentioned above 263 can be referred to the same structural group, where structures contain pairs of vanadate tetrahedra 264 oriented with respect to each other and shifted in three directions.
265 Acknowledgements:
Kovrugin V.M. et al. 9 266 This work was financially supported by St. Petersburg State University through the internal grant 267 3.38.238.2015 (A.N.Z.), RFBR 15-35-20632 (V.M.K.) and Russian President grant МК- 268 3756.2014.5 (O.I.S.). Technical Support by the X-Ray Diffraction and Geomodel Resource Centres 269 of Saint-Petersburg State University and the Natural History Museum (London) is gratefully 270 acknowledged.
271
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Kovrugin V.M. et al. 11 339 Rouse, R.C., Dunn, P.J., and Innes, J. (1986): Kombatite, the vanadium analogue of sahlinite, from 340 the Kombat mine, South West Africa. N. Jb. Mineral. Mh., 1986, 519–522.
3+ 5+ 341 Schindler, M. & Hawthorne, F.C. (1999): Schubnelite, [Fe (V O4)(H2O)], a novel 342 heteropolyhedral framework mineral. Am. Mineral., 84, 665–668.
343 Schindler, M., Hawthorne, F.C., Baur, W.H. (2000): Crystal chemical aspects of vanadium: 344 Polyhedral geometries, characteristic bond valences, and polymerization of (VOn) polyhedra. 345 Chem. Mater., 12, 1248–1259.
346 Shannon, R.D. & Calvo, C. (1973): Refinement of the crystal structure of low temperature Li3VO4 347 and analysis of mean bond lengths in phosphates, arsenates, and vanadates. J. Solid State 348 Chem., 6, 538–549.
349 Sheldrick, G.M. (2008): A short history of SHELX. Acta Crystallogr., A64, 112–22.
350 Sokolova, E., Hawthorne, F.C., Karpenko, V.V., Agakhanov, A.A., Pautov, L.A. (2004): Turanite, 2+ 5+ 351 Cu 5(V O4)2(OH)4, from the Tyuya–Muyun Radium–Uranium deposit, Osh district, 352 Kyrgyzstan: a new structure for an old mineral. Can. Mineral., 42, 731–739.
353 Starova, G.L., Krivovichev, S.V., Fundamensky, V.S., Filatov, S.K. (1997): The crystal structure of 354 averievite, Cu5O2(VO4)2∙nMX; comparison with related compounds. Mineral. Mag., 61, 441– 355 446.
356 Süsse, P. & Buerger, M.J. (1970): The structure of Ba3(VO4)2. Z. Kristallogr., 131, 161–174.
357 Uehara, S. & Shirose, Y. (2013): Namibite and hechtsbergite from the Nagatare mine, Fukuoka 358 Prefecture, Japan. J. Mineral. Petrol. Sci., 108, 105–110.
359 Vergasova, L.P., Starova, G.L., Ananiev, V.V. (1998): Averievite Cu5(VO4)2O2·nMX - a new 360 mineral of volcanic exhalations. Dokl. Earth Sci., 359A, 450–453.
361 Von Knorring, O. & Sahama, T.G. (1981): Namibite, a new copper-bismuth-vanadium mineral 362 from Namibia. Schweiz. Mineral. Petrog. Mitt., 61, 7–12.
363 Williams, S.A. (1988): Pottsite, a new vanadate from Lander County, Nevada. Mineral. Mag., 52, 364 389–390.
365 Yakubovich, O.V., Massa, V., Pekov, I.V. (2002): Crystal structure of the new mineral 366 bushmakinite, Pb2{(Al,Cu)[PO4][(V,Cr,P)O4](OH)}. Dokl. Earth Sci., 382, 100–105.
367 Zhesheng, M., Ruilin, H., Xiaoling, Z. (2009): Redetermination of the Crystal Structure of 368 Vesignieite. Acta Geol. Sin. – English Ed., 4, 145–151.
369
Kovrugin V.M. et al. 12 370
371 Table captions
372 Table 1. Electron microprobe analyses (wt.%) of pottsite.
373 Table 2. Crystallographic data and refinement parameters for pottsite.
374 Table 3. Atomic coordinates, site occupation factors (SOF) and equivalent or isotropic displacement 375 parameters (Å2) of atoms in the structure of pottsite.
376 Table 4. Displacement parameters (Å2) of atoms in the structure of pottsite.
377 Table 5. Selected interatomic distances in the structure of pottsite.
378 Table 6. Bond valence calculations (in valence units) for pottsite. Bond valence contribution was 379 weighted according to its occupancy.
5+ 380 Table 7. List of vanadate minerals contained the double-layered (DL) units composed of (V O4) 381 isolated tetrahedra, and their geometrical parameters.
382
Kovrugin V.M. et al. 13 383
384 Table 1. Selected electron microprobe analyses (wt. %) of pottsite
Analysis 1 2 3 4 5 6 7 Williams (1988)
Bi2O3 28.21 28.81 29.18 30.24 33.16 33.02 36.63 34.00 PbO 46.99 45.56 44.99 43.81 40.66 40.97 38.33 32.40 CaO 0.33 0.24 0.45 0.49 0.73 0.29 0.28
V2O5 23.96 23.71 23.50 23.89 23.86 23.91 24.25 26.60
As2O5 0.37 0.22 0.23 0.61
H2O 1.18 1.19 1.17 1.19 1.20 1.18 1.20 1.32 (6.71*) Total 100.67 99.88 99.51 99.85 100.22 99.37 100.69 94.32 (99.71*)
Bi 1.84 1.87 1.92 1.96 2.13 2.16 2.36 2.00 Pb 3.20 3.09 3.10 2.97 2.72 2.79 2.58 1.99 Ca 0.09 0.06 0.12 0.13 0.19 0.08 0.07 Total 5.13 5.03 5.14 5.06 5.04 5.03 5.00 3.99
V 4.00 3.95 3.97 3.97 3.92 4.00 4.00 4.00 As 0.05 0.03 0.03 0.08 Total 4.00 4.00 4.00 4.00 4.00 4.00 4.00 4.00 385 * original data from Williams (1988).
386 Table 2. Crystallographic data and refinement parameters for pottsite.
Crystal data: Crystal system tetragonal Space group I41/a a (Å) 11.0839(5) c (Å) 12.6516(6) Unit-cell volume (Å3) 1554.29(16) Z 1 Calculated density (g/cm3) 6.315 Absorption coefficient (mm–1) 55.49 Crystal size (mm) 0.18×0.16×0.12 Data collection: Temperature 293 K Radiation, wavelength (Å) MoKα, 0.71073 F(000) 2501 θ range (°) 2.44 – 32.48 h, k, l ranges −13→14, −9→16,
Kovrugin V.M. et al. 14 −17→19 Total reflections collected 5464 Unique reflections (Rint) 1385 (0.030) Unique reflections F>4σF 1167 Structure refinement: Full-matrix least- Refinement method squares on F2 Weighting coefficients a, b 0.0184, 40.1990 Data/restraints/parameters 1385/0/68 R1[F>4σF], wR2[F>4σF] 0.034, 0.063 R1 all, wR2 all 0.045, 0.065 Goodness-of-fit on F2 1.119 Largest diff. peak and hole 1.311, −1.445 eÅ–3 387 388
Kovrugin V.M. et al. 15 389 390 Table 3. Atomic coordinates, site occupation factors (SOF) and equivalent or isotropic displacement 391 parameters (Å2) of atoms in the structure of pottsite.
Atom SOF x y z Uiso*/Ueq
A(1) Pb0.542Bi0.388 0.72673(5) 0.14673(6) 0.08373(5) 0.01839(13) A(2) Pb0.070 0.7641(7) 0.1637(8) 0.0948(7) 0.0173(15) Bi(1) 0.816 ½ ¼ 7/8 0.02077(18) V(1) 0.40220(10) 0.0709(1) 0.11603(9) 0.0098(2) O(1) 0.3857(5) 0.1839(5) 0.0250(4) 0.0156(11) O(2) 0.5396(5) 0.0876(5) 0.1788(5) 0.0220(12) O(3) 0.3862(5) –0.0690(5) 0.0556(4) 0.0183(11) O(4) 0.2886(5) 0.0953(5) 0.2021(5) 0.0236(13) OW 0 ¼ 1/8 0.085(7)* 392
393 Table 4. Displacement parameters (Å2) of atoms in the structure of pottsite.
Atom U11 U22 U33 U12 U13 U23 A(1) 0.0198(3) 0.0160(3) 0.0194(2) 0.0038(2) 0.0015(2) 0.00198(17) A(2) 0.020(4) 0.016(3) 0.015(2) −0.003(3) −0.007(3) 0.0024(19) Bi(1) 0.0211(2) 0.0211(2) 0.0201(3) 0.000 0.000 0.000 V(1) 0.0095(5) 0.0082(5) 0.0118(5) 0.0001(4) 0.0007(4) 0.0013(4) O(1) 0.019(3) 0.014(3) 0.014(2) 0.003(2) 0.000(2) 0.002(2) O(2) 0.019(3) 0.024(3) 0.024(3) −0.009(2) −0.007(2) 0.005(2) O(3) 0.022(3) 0.015(3) 0.018(3) 0.002(2) −0.005(2) 0.000(2) O(4) 0.025(3) 0.028(3) 0.018(3) 0.002(2) 0.011(2) −0.002(2) 394
395 Table 5. Selected interatomic distances in the structure of pottsite.
Distance Å Distance Å A(1)−O(3)i 2.327(5) A(2)−O(2)iii 2.311(11) A(1)−O(1)ii 2.373(5) A(2)−O(4)iv 2.488(12) A(1)−O(2)iii 2.419(6) A(2)−O(1)ii 2.528(10) A(1)−O(4)iv 2.480(6) A(2)−O(4)v 2.693(11) A(1)−O(2) 2.486(6) A(2)−O(3)i 2.737(9) v vi A(1)−O(4) 2.852(6) A(2)−H2OW 2.810(7) A(1)−O(4)ii 3.233(6) A(2)−O(2) 2.834(10) vi ii A(1)−H2OW 3.2798(6) A(2)−O(4) 3.053(11)
Bi(1)−O(1) 2.396(5) 4× V(1)−O(4)v 1.687(6) Bi(1)−O(3) 2.527(5) 4× V(1)−O(1) 1.711(5)
397
Kovrugin V.M. et al. 16 398 399 Table 6. Bond valence calculations (in valence units) for pottsite. Bond valence contribution was 400 weighted according to its occupancy.
Σ SOF O(1) O(2) O(3) O(4) OW Σ SOF Pb 0.542 0.235 0.214, 0.186 0.258 0.189, 0.088, 0.041 0.0372x↓ 1.248 2.303 A(1) Bi 0.388 0.175 0.158, 0.138 0.192 0.159, 0.064, 0.029 0.0262x↓ 0.941 2.425 A(2) 0.070 0.022 0.034, 0.012 0.014 0.024, 0.016, 0.008 0.0124x↓ 0.142 2.029 Bi(2)* 0.816 0.3504x→ 0.2674x→ 2.468 3.025 V(1) 1.000 1.282 1.225 1.189 1.368 5.064 5.064 Σ 2.064 1.967 1.920 1.986 0.174 * special position on a fourfold rotoinversion axis 401
402
Kovrugin V.M. et al. 17 403
5+ 404 Table 7. List of vanadate minerals contained the double-layered (DL) units composed of (V O4) 405 isolated tetrahedra, and their geometrical parameters.
Chemical DL Height Internal Orien- Interlayer Interlayer Mineral name Ref. formula type of DL species tation distance species 2+ 2– Cu5O2 2+ – Cu , O , Averievite DL2 4.30 Å Cu , Cl (001) 3.91 Å – [1] (VO4)2∙CuCl2 Cl 2+ 3+ Pb2Mn 2+ Pb , Mn , Brackebuschite DL1 4.80 Å Pb (101) 1.82 Å – [2] (VO4)2(OH) (OH) 2+ 3+ Pb2Al(PO4) 2+ Pb , Al , Bushmakinite DL1 4.76 Å Pb (101) 1.87 Å – [3] (VO4)(OH) (OH) 2+ 3+ Pb2Fe 2+ Pb , Fe , Calderonite DL1 4.86 Å Pb (101) 1.73 Å – [4] (VO4)2(OH) (OH) 2+ 3+ Ba2Fe 2+ Ba , Fe , Gamagarite DL1 4.81 Å Ba (101) 1.92 Å – [5] (VO4)2(OH) (OH)
2+ 2+ Gurimite Ba3(VO4)2 DL1 4.19 Å Ba (001) 2.71 Å Ba [6] Bi O Hechtsbergite 2 DL4 4.25 Å Bi3+ (100) 2.19 Å Bi3+, (OH)– [7] (VO4)(OH) 2+ 2– Pb14O9 2+ Pb , O , Kombatite DL6 4.52 Å Pb (010) 6.59 Å – [8] (VO4)2Cl4 Cl PbMn Krettnichite 2 DL1 4.62 Å Pb2+ (001) 1.95 Å Mn3+ [9] (VO4)2(OH)2 PbFe Mounanaite 2 DL1 5.04 Å Pb2+ (001) 1.69 Å Fe3+ [10] (VO4)2(OH)2 3+ 2+ Cu(BiO)2 Bi , Cu , Namibite DL5 2.38 Å none (001) 4.51 Å – [11] (VO4)(OH) (OH) 2+ (Pb3,Bi)Bi Pb , Pottsite DL7 5.57 Å 3+ (001) 1.13 Å none [12] (VO4)4∙H2O Bi , H2O Fe3+, Schubnelite Fe(VO4)∙H2O DL3 4.79 Å (001) 1.39 Å none [13] H2O Cu Ba Vesignieite 3 DL1 4.23 Å Ba2+ (001) 2.54 Å Cu2+ [14] (VO4)2(OH)2 [1] (Starova et al., 1997; Vergasova et al., 1998); [2] (Donaldson & Barnes, 1955; Foley & Hughes, 1997); [3] (Pekov et al., 2002; Yakubovich et al., 2002); [4] (Del Tanago et al., 2003); [5] (de Villers, 1943; Harlow & Dunn, 1984; Basso et al., 1987); [6] (Süsse & Buerger, 1970; Mugavero et al., 2008); [7] (Krause et al., 1997; Uehara & Shirose, 2013); [8] (Rouse et al., 1986; Cooper & Hawthorne, 1994); [9] (Brugger et al., 2001); [10] (Cesbron & Fritsche, 1969; Werner Krause et al., 1998); [11] (von Knorring & Sahama, 1981; Kolitsch & Giester, 2000; Kolitsch & Götzinger, 2000; Uehara & Shirose, 2013); [12] (Williams, 1988), this work; [13] (Cesbron, 1970; Schindler & Hawthorne, 1999); [14] (Guillemin, 1955; Zhesheng et al., 2009). 406
407
Kovrugin V.M. et al. 18 408 409 Figure captions
410 Figure 1. X-ray element distribution map of Bi and Pb for 411 pottsite crystals showing zones enriched by Pb2+ or Bi3+.
412 Figure 2. Relationship between Pb and Bi (atoms per formula unit) for pottsite.
413 Figure 3. Coordination of A(1) site occupied by Bi3+ and Pb2+ cations and A(2) site occupied 2+ 414 exclusively by Pb (a), Bi(1) site – (b), V(1) – (c), and Ow – (d). Displacement ellipsoids are drawn 415 at 50% probability.
416 Figure 4. General projection of the crystal structure of pottsite along the a axis. Legend: VO4 417 tetrahedra are blue, A(1), A(2) and Bi(1) are black, grey, and yellow balls, respectively.
418 Figure 5. Projection of 2D block along the c axis in the structure of pottsite. Legend as in Fig. 3.
419 Figure 6. Projections of various DL complexes in the structures of vanadate minerals. See details in 420 text.
Kovrugin V.M. et al. 19 421
422
423
424 Fig. 1. X-ray element distribution map of Bi and Pb for pottsite crystals showing zones enriched by 425 Pb2+ or Bi3+ (online version in color).
426
427 Fig. 2. Relationship between Pb and Bi (atoms per formula unit) for pottsite.
Kovrugin V.M. et al. 20 428
429
430 Fig. 3. Coordination of A(1) site occupied by Bi3+ and Pb2+ cations and A(2) site occupied 2+ 431 exclusively by Pb (a), Bi(1) site – (b), V(1) – (c), and Ow – (d). Displacement ellipsoids are drawn 432 at 50% probability (online version in color).
433
Kovrugin V.M. et al. 21 434 435
436
437 Fig. 4. General projection of the crystal structure of pottsite along the a axis. Legend: VO4 438 tetrahedra are blue, A(1), A(2) and Bi(1) are black, grey, and yellow balls, respectively (online 439 version in color).
440
441
442
443 Fig. 5. Projection of 2D block along the c axis in the structure of pottsite. Legend as in Fig. 3 444 (online version in color).
445 Kovrugin V.M. et al. 22 446 447
448
449 Fig. 6. Projections of various DL complexes in the structures of vanadate minerals (online version 450 in color). See details in text.
451
Kovrugin V.M. et al. 23