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New zemannite-type phases, from Na 1.25 Fe 0.75 3 + Zn 1.25 ( Te O 3 ) 3 · 3 H 2 O to Na 0.55 Fe 1.44 3 + Zn 0.56 ( Te O 3 ) 3 · 3 H 2 O have been synthesised hydrothermally under basic conditions from a mixture of tellurium dioxide, zinc oxide, and either iron (III) oxide or iron (III) nitrate nonahydrate. Analysis by electron microprobe and inductively coupled plasma atomic emission spectrometry showed considerable variation in the Fe(III) and Zn contents of the framework. Single crystals of the compound produced from the iron (III) oxide syntheses were analysed, showing lower unit-cell parameters than natural zemannite, with a = 9.2620(9) and c = 7.6148(7) Å. The structure differs from type zemannite by the presence of Na and a water molecule which bridges the channel and framework by bonding via the oxygen atom. The unit-cell parameters of the compounds produced from iron (III) nitrate nonahydrate syntheses were refined from powder data and shown to increase with increasing pH. The results of this study show the potential for solid solution to exist in natural zemannite-type minerals and gives a stable boundary for the formation of pure zemannite-type compounds at basic pH levels, between pH 11.5 and pH 14.

The crystal structure of zemannite has been re-examined in order to address several features worthy of discussion. Analyses were performed on the type specimen and on material representative of Moctezuma. Type zemannite was found to refine in the space group P63 with a = 9.3877(5), c = 7.6272(4) Å and V = 582.12(7) Å3, whilst the unit-cell parameters in the same space group for the material representative of Moctezuma were a = 9.3921(13), c = 7.6230(15) Å and V = 582.3(2) Å3. The structural refinements undertaken were able to confirm for the first time the presence of a hydrogen bonding network in zemannite. An examination of the refinement of type zemannite in P63/m was also undertaken, showing that refining in the higher-symmetry space group does not show the ordering of framework octahedral metal cations. Zemannite-type minerals should therefore be refined in a non-centrosymmetric space group if possible, allowing the occupancies of the framework metal cations to refine. The chemical composition of zemannite was analysed by EMPA and by ICP-AES, showing conclusively that zemannite contains negligible Na, though the presence of Na should always be checked when analysing zemannite-type minerals. We also recommend that the formula of zemannite is revised to Mg0.5ZnFe3+(Te4+O3)3·(3 + n)H2O, where 0 = n = 1.5 from the current definition of Mg0.5ZnFe3+(Te4+O3)3·4.5H2O to better reflect the variable degree of hydration, since the type specimen is almost fully dehydrated and only contains three H2O molecules per formula unit.

We report the characterisation of two new tetrahedrite-group minerals, rozhdestvenskayaite, Ag10Zn2Sb4S13, and argentotetrahedrite, Ag6Cu4(Fe2+,Zn)2Sb4S13, and discuss the structural chemistry of the Ag-rich tetrahedrite group in order to identify correlations between structure and composition. Argentotetrahedrite is the Sb-analogue of argentotennantite. Rozhdestvenskayaite is named for Irina Rodzhdestvenskaya in recognition of her important contributions to mineralogy, and to the crystal chemistry of the tetrahedrite group in particular. Rozhdestvenskayaite is cubic I 4 ¯ 3 m with unit-cell parameter a = 10.9845(7) Å and V = 1325.37(15) Å3, and has a Mohs’ hardness of 3.0. Argentotetrahedrite is cubic I 4 ¯ 3 m with unit-cell parameter a = 10.6116(1) Å and V = 1194.92(2) Å3, and has a Mohs’ hardness of 3.9. The five strongest peaks in the X-ray powder diffraction patterns ([(hkl), dobs (Å), I/Imax (%)]) are: rozhdestvenskayaite [(222), 3.161, 100], [(004), 2.738, 35], [(044), 1.936, 24], [(226), 1.651, 19], [(134,015), 2.147, 18]; argentotetrahedrite [(222), 3.063, 100], [(044), 1.876, 35], [(004), 2.652, 28], [(226), 1.599, 25], [(134,015), 2.081, 19]. The large unit-cell volume of rozhdestvenskayaite is due to the high Ag content (70%) of the BS4 tetrahedron. A major issue for understanding the crystal chemistry of the tetrahedrite group relates to the occupancy of the Z site in which sulfur is coordinated octahedrally to monovalent metals (Cu or Ag). It is shown that this site can be completely empty, as in freibergite, and that this vacancy leads to a marked reduction in the volume of the Z(A6) octahedron from 16 Å3 in tetrahedrite with a fully occupied site to 11 Å3 in freibergite with a vacant Z site. In freibergite, the Ag–Ag distance of the Ag6 octahedron is 2.84 Å and is almost the same as that of silver metal (2.85 Å), strongly suggesting the presence of metallic bonding in this octahedral group. In contrast, the corresponding Ag–Ag distances of argentotetrahedrite and rozhdestvenskayaite are 3.23 Å and 3.24 Å, respectively, indicative of no metallic bonding. An important consequence of the metallically bonded Ag6 group of freibergite is that it has an aggregate formal charge of +4 (not +6), leading to a charge-balanced ideal formula (Ag6)4+(Cu+)4(Zn,Fe2+)2Sb4S12.

Wampenite, C18H16, is a new organic mineral from the fossil wood (conifer) locality at Wampen, Fichtelgebirge, Bavaria, Germany. It is monoclinic, space group P21/a, with a= 6.7331(19), b= 8.689(3), c= 23.709(7) Å, ß = 90.118(6)°, V= 1387.0(7) Å3 and Z= 4. Its structure was determined by single-crystal X-ray diffraction, which revealed that the molecular structure comprises an aromatic phenanthrene moiety with an axial methyl group at one end and a disordered propen-2-yl (methylvinyl) terminal group at the other. High resolution mass spectrometry (HRMS) confirmed the molecular formula C18H16and the IR spectrum is consistent with the molecular structure found.

We report the new mineral hydroxykenoelsmoreite, which has been approved by the IMA as IMA2016-056. The mineral occurs at the Masaka gold mine, Burundi, as rosettes up to 150µm across of platy crystals up to 20µm wide but <2µm thick, associated with goethite and galena. Crystals are canary yellow, transparent with a vitreous lustre, and have a pale yellow streak. Hydroxykenoelsmoreite is uniaxial (–) and non-pleochroic. The refractive indices were too high to measure, but the Gladstone-Dale compatibility index predicts nave= 2.065. Crystals are brittle with an irregular fracture, but have perfect cleavage on {0 0 1}. The Mohs hardness is ~3 by analogy with hydrokenoelsmoreite. The mineral is a member of the elsmoreite group of the pyrochlore supergroup, but deviates from the ideal cubic symmetry due mainly to ordering of Fe3+onto one of two W sites. Its structure is trigonal, space group R3, with unit-cell parameters a= 7.313(2), c= 17.863(7) Å, V= 827(1) Å3and Z= 6. The empirical formula (based on 7 (O + OH) per formula unit (pfu)) is: ([] 1.668Pb0.315Ca0.009Na 0.005K0.003Ba0.001)S2(W6+1.487Fe3+0.357Al0.156)S2(O4.119(OH)1.881)S6(OH). Raman spectroscopy and bond–valence sums showed that molecular H2O was absent or nearly so. The calculated density is 5.806 g cm-3.

Hydroxyferroroméite, ideally (Fe2+ 1.5[]0.5)Sb5+ 2O6(OH), is a new secondary mineral from the Correc d'en Llinassos, Oms, Pyrénées-Orientales Department, France. Hydroxyferroroméite occurs as yellow to yellow-brown powdery boxwork replacements up to about 50µm across after tetrahedrite in a siderite–quartz matrix. No distinct crystals have been observed. The empirical formula (based on 7 (O + OH) per formula unit, pfu) is (Fe2+ 1.07Cu2+ 0.50Zn0.03Sr0.03Ca 0.01[]0.36)S2 (Sb5+ 1.88Si0.09Al0.02As0.01)S2 O6 ((OH)0.86 O0.14). X-ray photoelectron spectroscopy was used to determine the valence states of Sb, Fe and Cu. Hydroxyferroroméite crystallises in the space group Fd3 m with the pyrochlore structure and hence is a new Fe2+ -dominant member of the roméite group of the pyrochlore supergroup. It has the unit-cell parameters: a = 10.25(3) Å, V = 1077(6) Å3 and Z = 8. A model, based on bond-valence theory, for incorporation of the small Fe2+ cation into a displaced variant of the A site of the pyrochlore structure is proposed.

Zincostrunzite (IMA2016-023), ZnFe3+; 2(PO4)2(OH)2· 6.5H2 O, is a new secondary phosphate mineral from the Sitio do Castelo tungsten mine in Portugal and the Hagendorf-Süd pegmatite in Germany. At Sitio do Castelo, zincostrunzite was derived from the alteration of triplite – zwieselite. At Hagendorf-Süd, it was found in a nodule of former triphylite that had been replaced by phosphophyllite and minor apatite. At Sitio do Castelo, zincostrunzite occurs as prisms up to 2 mm long. At Hagendorf-Süd, the mineral makes up portions of needles that are up to about 5 mm long. Crystals are elongated on [0 0 1] with the prism forms {0 1 0} and {1 1 0} and poorly formed terminations, probably {0 0 1}. Twinning is ubiquitous by 180° rotation on [0 1 0] with the composition plane {1 2 0}. Zincostrunzite crystals from Sitio do Castelo are light brownish yellow; those from Hagendorf-Süd are silvery white. The lustre is vitreous to silky and the streak is white. Crystals are brittle with irregular, splintery fracture and at least one perfect cleavage parallel to [0 0 1]; probably either {1 1 0} or {1 0 0}. The Mohs' hardness is about 2½. The measured density (Sitio do Castelo) is 2.66(1) g cm-3. At room temperature, the mineral is slowly soluble in dilute HCl and rapidly soluble in concentrated HCl. Optically, crystals are biaxial (-), with a = 1.620(2), ß = 1.672(2), ? = 1.720(2) (white light); 2 V meas. = 89.5(5)°; 2V calc. = 85.1°; orientation is Z ^c = 3°; X ˜ a*; pleochroism is X nearly colourless, Y light brownish yellow, Z darker brownish yellow (X < Y < Z). Electron-microprobe analyses gave the empirical formulas (Zn0.74 Mn2+ 0.23)S0.97 Fe3+ 1.99(PO4)2(OH)2·6.5H2 O (Sitio do Castelo) and (Zn0.93 Mn2+ 0.08)S1.01 (Fe3+ 1.84Mn2+ 0.19)S2.03 (PO4)2 (OH)2 ?6.5H2 O (Hagendorf-Süd). Zincostrunzite is triclinic, P -1, with a = 10.1736(6), b = 9.7999(5), c = 7.3296(2) Å, a = 91.325(4) °, ß = 97.895(6) °, ? = 116.948(4) °, V = 642.22(6) Å3 and Z = 2. The eight strongest lines in the X-ray powder diffraction pattern are [d obs/Å (I) (h k l)]: 8.87 (100) (100, 010, 1 1 0), 5.32 (95) (1 1 1, 011), 4.457 (30) (200), 4.287 (41) (020, 2 2 0), 3.310 (29) (120, 2 1 1), 3.220 (75) (multiple), 1.9116 (25) (multiple) and 1.6222 (32) (multiple). The crystal structure was refined to R 1 = 0.0715 for 3243 observed reflections [F o >4a F] for a crystal from Sitio do Castelo. The mineral is isostructural with other members of the strunzite group, except for an additional split H2 O site near the (½,0,0) centre of symmetry, which accounts for the additional 0.5 H2 O in the ideal formula. The extra H2 O site may be present in some crystals of other strunzite-group minerals, as its presence cannot be determined without a structure refinement.

Ferraioloite, MgMn2+ 4(Fe2+ 0.5Al3+ 0.5)4Zn4(PO4) 8(OH)4(H2O)20, is a new secondary phosphate mineral from the Foote Lithium Company mine, Kings Mountain district, Cleveland County, North Carolina, USA. The mineral was found in tiny vughs within a thin seam of very fine-grained, sugary pegmatite with vivianite, fairfieldite/messelite, phosphophyllite, scholzite/ parascholzite, rittmannite, mangangordonite, kingsmountite, kastningite and metaswitzerite. Ferraioloite crystals occur as very thin greenish grey to lemon yellow plates or blades up to about 0.2 mm in length, but no more than a few m m thick. Crystals are biaxial (À), with indices of refraction a = 1.575(calc), ß = 1.5825(5), ? = 1.5835(5), 2V (meas.) = 40(5). Dispersion is weak:r > v, the orientation is: X~ a, Y = b , Z ~ c and pleochroism: X, Z = colourless, Y = blue grey; Y> > X ~ Z. The empirical formula (based on 56 O atoms pfu) is Ca0.21 Mg0.50 Mn2+ 4.16Fe2+ 2.05Al3+ 2.01Zn 4.27P8.00H43.59O56. Ferraioloite is monoclinic, space group I2/ m, with the unit-cell parameters: a = 25.333(3) Å, b = 6.299(1) Å , c = 15.161(3) Å , b = 90.93(3) and V = 2419.0(2) Å3. Ferraioloite has a heteropolyhedral layer structure with layers parallel to (100) and with isolated Mg(H2 O)6 octahedra and water molecules packing between the layers. The heteropolyhedral slabs have the same topology as falsterite, with Mn2+ replacing Ca2+ and with Al3+ substituting for Fe3+.

Kayrobertsonite, MnAl2 (PO4)2 (OH)2·6H2 O, is a new secondary phosphate mineral from the Hagendorf Süd pegmatite, Hagendorf, Oberpfalz, Bavaria, Germany and the Foote Lithium Company mine, Kings Mountain district, Cleveland County, North Carolina, USA. Kayrobertsonite crystals occur as intergrown masses of snow-white, soft, finely fibrous needles, less than 5 µm in diameter and no more than 100 m m in length. Quantitative analysis of Foote mine kayrobertsonite gave the empirical formula: Mn0.97 Ca0.03 Fe0.02 Al1.87 (PO4)2 (OH)1.62 F0.03 (H2 O)0.38 6H2 O; and for Hagendorf Süd kayrobertsonite: Mn0.92 Ca0.06 Fe0.02 Al1.87 (PO4)2(OH)1.19 F0.42 (H2O)0.39 6H2 O. Foote mine kayrobertsonite crystals are biaxial (–), with indices of refraction a = 1.530(1), b = 1.554(1), g = 1.566(1), measured in white light; 2 V (meas.) is 70.3(5)°, while 2 V (calc.) is 69.6 . The mineral is nonpleochroic. The orientation of the crystals is Z ~ c (length slow). Kayrobertsonite is triclinic, space group P1, with the unit-cell parameters: a = 10.049(2), b = 10.205(2), c = 6.083(1) Å , a = 91.79(3), b = 99.70(3), g = 98.02(3)Å, V = 607.9(2) Å3 and Z = 2 (Foote mine). The polyhedral framework in kayrobertsonite has the same topology as that in nordgauite, but with replacement of F by OH at the bridging anion sites. The main crystal chemical change from nordgauite to kayrobertsonite is a doubling of the number of water molecules in the [001] channels.

Alfredopetrovite, Al2 (Se4+ O3)3 6H2 O, is a new secondary selenite mineral from the El Dragón mine, Antonio Quijarro Province, Potosí Department, Bolivia. The mineral occurs in vugs in a matrix of Co-rich krut'aite–penroseite, dolomite and goethite. Associated minerals are: ahlfeldite, allophane, calcite, chalcomenite, favreauite, felsobányaite, malachite and molybdomenite. Crystals occur in drusy/scaly coatings and compact balls, the latter to 0.5 mm in diameter. Individual crystals are up to about 0.1 mm across. The Mohs hardness of alfredopetrovite is 2½ it has no cleavage, curved fracture and a vitreous lustre. The calculated density based on the empirical formula is 2.504 g cm3. Alfredopetrovite is uniaxial (+), with ? = 1.554(2) and e = 1.566(2) (white light), and exhibits no pleochroism. Electron microprobe analyses gave the empirical formula Al1.94 Cu0.07 Ni0.03 Co0.01 Se2.95 O15 H12.16, based on 15 O apfu. Alfredopetrovite is hexagonal, space group P 6 2 c, with the unit-cell parameters: a = 8.818(3) Å , c = 10.721(2)Å , V = 722.0(5) Å 3and Z = 2. The eight strongest lines in the X-ray powder diffraction pattern are [d obs/Å (I) (hkl)]: 7.63(55)(100), 6.22(55)(101), 5.37(26)(002), 4.398(40)(110,102), 3.404(100)(112), 2.783(50)(211), 2.606(22)(203), and 1.6609(26)(410,322,314,116). The crystal structure was refined to R 1 = 0.0268 for 240 observed reflections [F o. > 4sF]. The structure is comprised of fairly regular AlO6 octahedra and Se4+ O3 triangular pyramids. Three Se4+ O3 pyramids link two adjacent AlO6 octahedra forming a [Al(H2O)3]2 (Se4+ O3)3 cluster structural unit. These structural units are bonded to one another only via hydrogen bonds yielding a structure with relatively large channels along [001]. The configuration of the cluster is similar to that of the distinctive unit in the NASICON structure, commonly referred to as a lantern unit.

The type specimen of partzite has been reinvestigated by powder X-ray diffraction and electron microprobe traverses. Re-examination of the type material shows that it is a mixture of several phases, intergrown on a submicrometre scale and hence not fully resolved by electron microprobe. Investigation of major-element spot analyses for correlations between elements indicates that the two dominant phases are a plumboroméite-like oxide phase and a chrysocolla-like amorphous Cu silicate. This analysis also suggested the presence of several minor phases that were too scarce to be detectable by X-ray diffraction, including acanthite, chlorargyrite, baryte, halite, and an Al-rich clay mineral. Lack of correlation between Si-corrected Cu content and Sb content implies that Cu is not a significant component of the roméite-group mineral. Partzite is therefore discredited as a valid mineral species. This proposal has been approved by the IMA CNMNC (proposal 16–B).

Favreauite, ideally PbBiCu6O4(SeO3)4(OH)·H2O, is a new secondary selenite mineral from the El Dragón mine, Antonio Quijarro Province, Potosí Department, Bolivia. The mineral occurs in vughs in a matrix of (Co, Cu)-rich penroseite, dolomite and goethite. Associated minerals are: ahlfeldite, allophane, calcite, chalcomenite, malachite, molybdomenite and an unnamed Al selenite. Favreauite forms tiny green square tabular crystals, flattened on {001}, up to 0.1 mm on edge and 0.01 mm thick, occurring in subparallel and divergent groups. The Mohs hardness of favreauite is estimated as ~3; it has perfect cleavage on {001}, an irregular fracture and a vitreous lustre. The calculated density based on the empirical formula is 4.851 g cm3. Favreauite is uniaxial (–), with mean refractive index estimated as 1.854 from the Gladstone–Dale relationship. It is pleochroic in shades of green, O < E. Electron microprobe analyses gave the empirical formula Pb0.95Ca0.17Bi0.90Cu5.81Se4.10O16(OH)·1H2O, based on 18 O pfu. The Raman spectrum shows strong SeO3 bands at 847 cm1 (?1), 764 and 795 cm1 (?3), 493 and 542 cm1 (?2), and 320 and 392 cm1 (?4). Favreauite is tetragonal, space group P4/n, with the unit-cell parameters: a = 9.860(4) Å, c = 9.700(5) Å, V = 943.0(9) Å3 and Z = 2. The eight strongest lines in the X-ray powder diffraction pattern are [d obs/Å (I) (hkl)]: 5.67(100)(111), 3.470(76)(220,202), 3.190(35)(003), 2.961(40)(311,113), 2.709(33)(302,203), 2.632(34)(231,312), 2.247(36)(331,133), and 1.6652(33)(305,513,531). The crystal structure was refined to R 1 = 0.0329 for 1354 observed reflections [F o < 4sF o] and 0.0356 for all 1432 unique reflections. Favreauite is a close structural relative of nabokoite, KCu7Te4+O4(SO4)5Cl, and atlasovite, KCu6Fe3+BiO4(SO4)5Cl. In all cases, oxygen-centred tetrahedra share edges to form corrugated [Cu6 MO4] layers (M = Bi or Te) which can be derived from the framework structure of murdochite, Pb4+Cu2+ 6O8-x (Cl,Br)2x by selective deletion of atoms. In favreauite, additional OH and H 2O between the layers are weakly bound to Cu, giving it Jahn-Teller distorted 4 + 2 coordination. The Cu–Bi–O layer is braced by SeO 3pyramids. The Bi3+ and interlayer Pb2+ form an approximately face-centred cubic array analogous to the Pb4+ sites in murdochite. Unlike Bi3+, Pb2+ is in a site with nonpolar 4 point symmetry, which suppresses the stereoactivity of its lone pair.

New data for parnauite from the type locality, Majuba Hill, Nevada, USA (MH; type specimen), and also from Cap Garonne, Var, France (CG), and the Clara Mine, Baden-Württemberg, Germany, are presented. The average chemical composition of MH material is (Cu8.82Al0.16Fe0.02)? 9.00(As1.78Al0.07Si0.08S0.07)? 2.00O8(SO4)(OH)10 · 7H2O and that of CG parnauite, (Cu8.42Al0.21Zn0.10)? 8.73(AsO4)2[(S0.97As0.10)? 1.07O4](OH9.23Cl0.77)? 10.00 · 7H2O. Both of these formulae confirm the 9:2:1 Cu:As:S ratio obtained from earlier descriptions of parnauite. Raman spectra for parnauite from both localities are very similar. Bands are assigned, but show no evidence of the presence of CO3, in contrast to previous studies, and no distinct Cu?Cl stretching mode. It appears that neither the minor CO3 and PO4 previously reported nor Cl are essential constituents of parnauite. Single-crystal XRD analysis indicates a primitive orthorhombic unit cell with dimensions 6 × 14 × 15 Å, similar to previous studies, but h = odd reflections were heavily streaked and diffuse, preventing full refinement. A 3 Å substructure was refined, with space group Pmn21, to R 1(F) = 0.0750 (MH). For a MH crystal, the subcell had a = 3.0113(4), b = 14.259(3), c = 14.932(2) Å, V = 641.13(16) Å3 and Z = 1. The structure is of a new type, and contains Cu in 6 distinct sites, forming two three-polyhedron wide ribbons of edge-sharing Cu-O polyhedra extended parallel to the a-axis. The two ribbons lie back-to-back and are bridged by two AsO4 tetrahedra. The collection of 6Cu + 2As cations plus ligands forms a rod-like moiety extended || a. These rods link through polyhedral corners to form complex, corrugated (010) layers. The interlayer space is occupied by H2O molecules. Thus, the disorder observed by XRD is of an unusual type, in which the shape of the unit mesh within layers is variable, rather than the stacking of the layers. Disorder arises because each AsO4 tetrahedron shares a face with a Cu(O, OH, H2O)5-6 polyhedron in the substructure, necessitating partial occupancy of both As and Cu sites. The S atoms were not located in the refinement, but four electron-density maxima in the interlayer region were interpreted as H2O molecules. Hence, the simplified structural formula derived from the substructure is (Cu10?2)(As2?2)O8(OH)148H2O, deviating from that obtained in chemical analyses. The discrepancy presumably arises due to strong delocalisation of the sulphur and the apical oxygen of the SO4 tetrahedron in the substructure. Short-range order of Cu?As and Cu?S || a can occur independently in the relevant structural rods, which accounts for the observed long-range disorder. Cell parameters and substructures obtained from CG and Clara material are similar to those from the MH crystal. Site splitting of OH positions in the CG refinement indicates that Cl is distributed over several sites in the 3 Å substructure, making the mineral a Clrich variety of parnauite rather than a distinct mineral species.

Paseroite, ideally PbMn2+(Mn2+,Fe2+)2(V5+,Ti,Fe3+,)18O38, is a new mineral (IMA2011-069) from fossil wood in the upper part of the Molinello mine, Val Graveglia, Italy. Paseroite occurs in direct association with quartz, chalcocite, volborthite, metatyuyamunite and pyrophanite, and was also found as zones within V-rich senaite crystals with which it forms a solid-solution series. Paseroite forms as isolated submetallic, dark grey to black, elongated scalenohedral crystals between 50 and 100 m m in length, with the forms {001} and {102} present. The tenacity is brittle, the fracture conchoidal, and the streak is black. The Vickers hardness is 847 kg mm-2 (load 500g), which is equivalent to 6-6.5 on the Mohs scale. The calculated density is 4.315 g/cm3 (on the basis of the empirical formula). In plane-polarised incident light, paseroite is greyish in colour, weakly bireflectant and non-pleochroic. Internal reflections are absent. Between crossed polars, paseroite is anisotropic, without characteristic rotation tints. Reflectance percentages (Rmin and Rmax) are: 18.4 %, 18.2 % (471.1 nm); 17.9 %, 17.7 % (548.3 nm); 17.6 %, 17.3 % (586.6 nm); and 17.0 %, 16.8 % (652.3 nm), respectively. The empirical formula, calculated on the basis of 38 O atoms pfu is: (Pb0.61Sr0.39)S1.00 (V5+7.78Ti4+7.03Mn2+1.86Fe2+0.67Fe3+0.37Zn0.24Na0.19U0.02Mg0.022.82)S21.00O38. According to the structural results, the simplified formula is: PbMn2+(Mn2+,Fe2+)2(V5+,Ti,Fe3+,)18O38. Structurally, paseroite crystallises in the space group R3, with the unit-cell parameters a = 10.3894(5), c = 20.8709(8) Å, V = 1950.98(15) Å3 and Z = 3. The crystal structure was refined to R = 0.0234 for 632 reflections with Io > 2s(Io) and is isostructural with senaite and all other members of the crichtonite group. The eight strongest X-ray powder-diffraction lines [d in Å (I/I0) (hkl)] are: 3.417 (100) (024), 3.012 (21) (300), 2.896 (61) (216), 2.858 (36) (214), 2.765 (27) (303), 2.260 (85) (144), 2.149 (65) (415) and 1.809 (57) (418). The name is after Marco Pasero (b. 1958), Professor of Mineralogy at the University of Pisa.