Journal of Geosciences, 60 (2015), 123–127 DOI: 10.3190/jgeosci.190 Letter to editor Crystal structure refinement of pseudojohannite, Cu3(OH)2[(UO2)4O4(SO4)2](H2O)12, from the type locality – Jáchymov, Czech Republic Jakub PLÁŠIL1* 1 Institute of Physics, Academy of Sciences of the Czech Republic v.v.i., Na Slovance 2, 182 21 Prague 8, Czech Republic; [email protected] * Corresponding author The crystal structure of pseudojohannite from the type locality, Jáchymov (Western Bohemia, Czech Republic), was solved by charge-flipping method from single-crystal X-ray diffraction data and refined to an R = 0.0385 against 2072 unique observed reflections. Pseudojohannite from Jáchymov is triclinic, P¯1, with a = 8.6653(4), b = 8.8499(5) Å, c = 9.9908(6), α = 72.103(6), β = 70.512(5)°, γ = 76.070(5)°, V = 679.12(7) Å3 and Z = 1. The structural formula derived from the refinement and bond-valence considerations is Cu3(OH)2[(UO2)4O4(SO4)2](H2O)12, confirming previous structure determination on the material from Widowmaker mine, Utah, USA. Contrary to other members of the zippeite-group, the interstitial metal sites in pseudojohannite (populated by Cu2+), are fully occupied and the structure tends to be fully ordered with no important departure from the ideal stoichiometry. Keywords: pseudojohannite, uranyl sulphate, zippetite group, crystal structure, Jáchymov Received: 16 January 2015; accepted: 3 March 2015; handling editor: F. Laufek The online version of this article (doi: 10.3190/jgeosci.190) contains supplementary electronic material. 1. Introduction type locality, Jáchymov, has never been disclosed. In the paper of Plášil et al. (2012) the results of Rietveld refine- Pseudojohannite is one of two known copper-bearing ment on the powder data for pseudojohannite are given; uranyl sulfates formed from oxidation–hydration weath- however, only positions of the uranium atoms could be ering of uraninite in the presence of copper sulphide refined from the data. Here we present a short report minerals as chalcopyrite or tennantite (Krivovichev on the crystal structure refinement of pseudojohannite and Plášil 2013; Plášil 2014). It was first described from the type locality, providing similar results as for by Ondruš et al. (1997, 2003) as a new mineral from pseudojohannite from USA, showing no discrepancies or Jáchymov (St. Joachimsthal), Western Bohemia, Czech inconsistencies. This suggests that these structures tend to Republic. Originally it was reported to be triclinic, be ordered, in contrast to other members of the zippeite group (see e.g., Burns et al. 2003). Cu5(UO2)6(SO4)3(OH)16(H2O)14, with a = 13.754(2), b = 9.866(1), c = 8.595(2) Å, α = 103.84(2)°, β = 90.12(2)°, γ = 106.75(2)°, and V = 1081.3(4) Å3. Brugger et al. (2006) concluded that pseudojohannite is a member 2. Sample of the zippeite group, based on the characteristic U:S ratio 2:1 (Burns 2005; Krivovichev and Plášil 2013), The crystal of pseudojohannite investigated by single- and they revised chemical formula of pseudojohannite crystal X-ray diffraction was recovered from the speci- men originating from the Červená vein, Rovnost mine in accordingly to Cu6.5[(UO2)4O4(SO4)2]2(OH)5(H2O)25. The final conclusion that pseudojohannite is a member of Jáchymov, Czech Republic. The specimen was already the zippeite-group of minerals was documented by the studied in course of the detailed mineralogical study by full crystal structure solution presented by Plášil et al. Plášil et al. (2014a). The crystal aggregate was recovered (2012) on the material from Widowmaker mine, White from a rich specimen, of the size 6 × 4 × 1.5 cm, repre- Canyon, Utah, USA. According to them, pseudojohan- senting a fragment of the ore-vein, containing U- and nite is triclinic, P¯1, with a = 8.6744(4), b = 8.8692(4), Cu- ore mineralization (uraninite, chalcopyrite, tennantite c = 10.0090(5) Å, α = 72.105(4)°, β = 70.544(4)°, and chalcocite). Pseudojohannite forms well-developed γ = 76.035(4)°, and V = 682.61(5) Å3, and its chemical crystals up to 0.2 mm across. They have a typical lens or half-lens shape, characteristic of the zippeite-group formula is Cu3(OH)2[(UO2)4O4(SO4)2](H2O)12, Z = 1. Nevertheless, the structure of pseudojohannite from the minerals (cf., Plášil et al. 2010, 2014a). www.jgeosci.org Jakub Plášil 3. Single-crystal X-ray crystallography tions and provided triclinic unit cell with a = 8.6653(4), b = 8.8499(5) Å, c = 9.9908(6), α = 72.103(6), β = A tiny plate-like greenish crystal of pseudojohannite, with 70.512(5)°, γ = 76.070(5)°, V = 679.12(7) Å3 and Z = dimensions 0.14 × 0.05 × 0.02 mm, was selected under 1. From the total of 4779 measured diffractions, 2550 the optical stereomicroscope. The intensity data were were independent and 2072 classified as observed [Iobs collected using Oxford Diffraction Gemini single-crystal > 3σ(I)]. Data were corrected for background, Lorentz diffractometer equipped with an Atlas CCD detector and and polarization effects, and an analytical correction for absorption was applied (Clark and Reid 1995), leading using monochromated MoKα radiation from conventional sealed X-ray tube (55 kV, 45 mA), collimated with fiber- to Rint of the merged data equal to 0.042. optics Mo-Enhance collimator. The unit cell was refined Crystal structure was solved from X-ray diffrac- by a least-squares algorithm using the CrysAlis Pro tion data by the charge-flipping algorithm (Palatinus Package (Agilent Technologies 2014) from 2818 reflec- and Chapuis 2007), independently from the previ- ous structure solution (Plášil Tab. 1 Crystallographic data and refinement details for pseudojohannite from Jáchymov et al. 2012). Obtained model was refined by the full-matrix Crystal data least-squares of the Jana2006 Structure formula U4Cu3S2O34H26 program (Petříček et al. 2006, Crystal system triclinic 2014). All atoms were found Space group P¯1 from the structure solution, ex- Unit-cell parameters: a, b, c [Å] 8.6653(4), 8.8499(5), 9.9908(6) cept of several O sites, belong- α, β, γ [°] 72.103(6), 70.512(5), 76.070(5) ing to the H2O molecules in Unit-cell volume [Å3] 679.12(7) the interlayer of the structure; Z 1 those atoms were localized Calculated density [g/cm3] 4.345 later by the difference-Fourier syntheses. Careful inspection Crystal size [mm] 0.14 × 0.05 × 0.02 of the diffraction frames re- F 759 000 vealed presence of reflections that could not be indexed based Data collection on the single domain; therefore, Diffractometer Oxford Diffraction Gemini with Atlas detector second crystal-domain was in- Temperature [K] 293 troduced into the refinement. Radiation, wavelength [Å] MoK , 0.71073 (50 kV, 30 mA) α Their relation is expressed by θ range for data collection [º] 2.87−29.51 the twin-matrix given in the Limiting Miller indices h = –11→8, k = –11→10, l = –12 → 9 Tab. 1. In total, 565 reflections Axis, frame width (º), time per frame (s) ω, 1, 350 were discarded from the fit, Total reflections collected 4779 since they were detected as Unique reflections 2550 fully or partially overlapping. Unique observed reflections, criterion 2072, [I > 3σ(I)] The final refinement including Absorption coefficient [mm-1], type 26.34; analytical all atoms refined with aniso- tropic displacement parameters Tmin/Tmax 0.514/1 converged quickly to an R1 = Rint 0.042 0.0385, wR2 = 0.0818 with a GOF = 1.30 for 2072 unique Structure refinement by Jana2006 Full-matrix least-squares on F2 observed reflections. No cell Number of refined parameters, restraints, constraints 198, 0, 0 of higher symmetry was found R, wR (obs) 0.0385, 0.0818 using LePage and ADDSYMM R, wR (all) 0.0476, 0.0865 (Spek 2003, 2009). Details of GOF obs/all 1.30, 1.23 the data collection and miscel- Weighting scheme, weights σ, w =1/(σ2(I)+0.0004I2) laneous crystallographic and Extinction (Gaussian, Becker and Coppens 1974) 210(30) structure refinement parameters Largest diffraction peak and hole (e–/Å3) 1.71, –2.81 are listed in Tab. 1. Final atom −−1 0 0.6357 coordinates and their displace- 0−− 1 0.5454 Twin matrix 00 1 ment parameters are given in Twin fractions 0.889(5)/0.111(5) Tab. 2. The CIF file, containing 124 Crystal structure refinement of pseudojohannite al. 2009) atoms incompared structures (Orobengoa et the distances ofpaired (symmetrically equal) S= 2007) al. et las (Capil distortion lattice of degree 2012): al. et calculated e.g.,byprogramCOMPSTRU(Tasci similarity of measures using compared be can USA) (Plášil et al. 2012). The two structures White Canyon(Utah, mine, Widowmaker the from crystal studied previously the to identical Jáchymov (CzechRepublic)ismoreorless and in rabejacite (Plášil et al. 2014b). 2003) al. et (Burns cations metal alkaline-earth or metal divalent contain that zippeites synthetic siozippeite (Plášil et al. 2013), in isostructural magne in e.g., found were pseudojohannite in sheetsofthesamecompositionas particular, (Burns 2005; Krivovichev and Plášil 2013). In minerals of zippeite-group the of characteristic structural sheetsfoundinpseudojohanniteis the of topology The only. bonds hydrogen by linked is and layers structural adjacent the interstitial complexisnotbondeddirectlyto such adistanceistypicalofstructureswhere in marécottite(9.47Å;Bruggeretal.2003); eter), issimilartotheinterlayerdistancee.g. the to equivalent is Å(which 9.99 of c These sheetsarestackedperpendiculartothe the composition [(UO composition the ered, consistingofuranyloxo-sulfatesheets, lay is pseudojohannite of structure 2012).The tailed bond-valenceconsiderations(Plášiletal. de and complex interstitial the of chemistry including adetaileddiscussiononthestereo in detailbythepreviouscrystalstructurestudy, The structure ofpseudojohannite was described 4. page web Journal’s the also ablockwith thereflections, is deposited at nating interlayercomplex[Cu et al.