The progressive crystallization of dolomite has been investigated in the temperature range of 90 to 410°C by means of X-ray powder diffraction, electron microscopy, and infra-red spectroscopy.

Short-time, low-temperature experiments (≤ 145°C yielded dolomites with a high defect density. In detail, lattice faults can be described as: Random succession of more or less ordered cation domains, producing a long-range mosaic-type disorder; cation ordering may take place along <101̄0> and <112̄0> tilting and dislocation of individual CO3 groups; and irregular interstratification of dolomite layers of different chemical compositions in the crystallographic c-directions.

Dolomites produced in experiments of longer duration are composed of an interstratification of essentially two chemically different dolomite layers, of which the stacking sequence is more perfect than it is at lower crystallization degrees. Both components grow rapidly at the expense of dolomites of intermediate composition. Finally, long-term low-temperature (145°C) experiments produced two independent, coexistent dolomite phases. Within single dolomite layers cations now lie very close to their theoretical positions. CO3-tilting and dislocation decreases markedly.

Hydrothermal runs at temperatures > c. 145°C yielded one single, nearly stoichiometrie, highly ordered dolomite phase. Finally, dolomites synthesized at temperatures > c. 200°C are of an ideal chemical composition and have perfect lattice ordering.

Veblenite, ideally K2☐2Na(Fe2+5Fe3+4Mn2+7☐)Nb3Ti(Si2O7)2(Si8O22)2O6(OH)10(H2O)3, is a new mineral with no natural or synthetic analogues. The mineral occurs at Ten Mile Lake, Seal Lake area, Newfoundland and Labrador (Canada), in a band of paragneiss consisting chiefly of albite and arfvedsonite. Veblenite occurs as red brown single laths and fibres included in feldspar. Associated minerals are niobophyllite, albite, arfvedsonite, aegirine-augite, barylite, eudidymite, neptunite, Mn-rich pectolite, pyrochlore, sphalerite and galena. Veblenite has perfect cleavage on {001} and splintery fracture. Its calculated density is 3.046 g cm–3. Veblenite is biaxial negative with α 1.676(2), β 1.688(2), γ 1.692(2) (λ 590 nm), 2Vmeas = 65(1)°, 2Vcalc = 59.6°, with no discernible dispersion. It is pleochroic in the following pattern: X = black, Y = black, Z = orange-brown. The mineral is red-brown with a vitreous, translucent lustre and very pale brown streak. It does not fluoresce under short and long-wave UV-light. Veblenite is triclicnic, space group P, a 5.3761(3), b 27.5062(11), c 18.6972(9) Å, α 140.301(3), β 93.033(3), γ 95.664(3)°, V = 1720.96(14) Å3. The strongest lines in the X-ray powder diffraction pattern [d(Å)(I)(hkl)] are: 16.894(100)(010), 18.204(23)(01), 4.271(9)(, 040, 120), 11.661(8)(001), 2.721(3)(), 4.404(3)(, ), 4.056(3)(031, 12; , ), 3.891(2)(003).

The chemical composition of veblenite from a combination of electron microprobe analysis and structural determination for H2O and the Fe2+/Fe3+ ratio is Nb2O5 11.69, TiO2 2.26, SiO2 35.71, Al2O3 0.60, Fe2O3 10.40, FeO 11.58, MnO 12.84, ZnO 0.36, MgO 0.08, BaO 1.31, SrO 0.09, CaO 1.49, Cs2O 0.30, K2O 1.78, Na2O 0.68, H2O 4.39, F 0.22, O = F –0.09, sum 95.69 wt.%. The empirical formula [based on 20 (Al+Si) p. f. u. is (K0.53Ba0.28Sr0.03☐0.16)Σ1(K0.72Cs0.07☐1.21)Σ2(Na0.72Ca0.17☐1.11)Σ2(Fe2+5.32Fe3+4.13Mn2+5.97Ca0.70Zn0.15Mg0.07☐0.66)Σ17(Nb2.90Ti0.93Fe3+0.17)Σ4(Si19.61Al0.39)Σ20O77.01H16.08F0.38. The simplified formula is (K, Ba, ☐)3(☐, Na)2(Fe2+, Fe3+, Mn2+)17(Nb,Ti)4(Si2O7)2(Si8O22)2O6(OH)10(H2O)3. The infrared spectrum of the mineral contains the following bands (cm–1): 453, 531, 550, 654 and 958, with shoulders at 1070, 1031 and 908. A broad absorption was observed between ~3610 and 3300 with a maximum at ~3525. The crystal structure was solved by direct methods and refined to an R1 index of 9.1%. In veblenite, the main structural unit is an HOH layer, which consists of the octahedral (O) and two heteropolyhedral (H) sheets. The H sheet is composed of Si2O7 groups, veblenite Si8O22 ribbons and Nb-dominant D octahedra. This is the first occurrence of an eight-membered Si8O22 ribbon in a mineral crystal structure. In the O sheet, (Fe2+, Fe3+, Mn2+) octahedra share common edges to form a modulated O sheet parallel to (001). HOH layers connect via common vertices of D octahedra and cations at the interstitial A(1,2) and B sites. In the intermediate space between two adjacent HOH layers, the A(1) site is occupied mainly by K; the A(2) site is partly occupied by K and H2O groups, the B site is partly occupied by Na. The crystal structure of veblenite is related to several HOH structures: jinshanjiangite, niobophyllite (astrophyllite group) and nafertisite. The mineral is named in honour of David R. Veblen in recognition of his outstanding contributions to the fields of mineralogy and crystallography.

The first Italian occurrence of cumengéite, a rare Pb and Cu hydroxychloride, is described from Vesuvius (Italy). Italian cumengéite has a volcanic origin (it occurs in the fumarole), which is unique for that mineral. The mineralogy of Vesuvius' fumarole is outlined briefly. A powder X-ray diffraction (XRD) pattern of cumengéite is presented. The crystal structure of cumengéite has been refined (R = 0.036) using single-crystal XRD data. Cumengéite is tetragonal, space group I4/mmm, a 15.1007(2), c 24.4940(4) Å. In the structure of cumengéite there are five independent Pb atoms, which are linked to 6—9 anions in five different ways. The structural study revealed the presence of two independent and previously unobserved water molecules, and led to the revision of the accepted chemical formula for the mineral: the new formula is Cu20Pb21Cl42(OH)40·6H2O. Analytical data taken from the literature for cumengéite from Boléo, Mexico (the type locality), as well as a new structural study carried out on the type material confirmed the new formula.

The holotype roggianite from Alpe Rosso (Novara, Italy) has been chemically re-analysed using modern analytical procedures (microprobe, atomic absorption spectrophotometer, TG analyses) and tested for its zeolitic behaviour. When compared with that given in the original description, the new chemical composition shows an appreciable amount of Be and a different Si/Al ratio. On the basis of its structural data, the chemical formula here proposed for roggianite is: (Ca14.24Sr0.01Na0.37K0.56)Σ15.18[(Be5.29Al14.92Si27.79)Σ48O89.96(OH)14](OH)2·33.68H2O

An accurate powder pattern, index taking into account the structural factors, is also given. Since the mineral showed an almost complete rehydration after heating to 750°C and an appreciable ion exchange capacity, it must be considered as belonging to the zeolitic group of minerals, and, in this frame, it represents the first and up to now the only zeolite with Be as fundamental constituent and, like partheite, with OH groups in the framework.

A second occurrence of the mineral bolivarite has been found in the Kobokobo pegmatite, Kivu, Republic of Congo (Kinshasa). This amorphous mineral was previously considered to be evansite. Its physical properties are: weak birefringence; biaxial to uniaxial positive; n = 1·50–1·51; specific gravity 1·97–2·05; hardness 3 to 3½.

Three chemical analyses have been performed on the Congolese material. The general formula of the mineral is Al2(PO4)(OH)3.4–5 H2O. Both known bolivarites from Spain and Congo contain abnormal amounts of U. The bright green UV fluorescence is due to the presence of U. The DTA curve of the Congolese bolivarite is given. Its genesis is discussed. This uranium-bearing mineral may be an indicator of uranium mineralization in Spain.

The crystal structure of argentobaumhauerite is reported for the first time from a sulfosalt aggregate from Lengenbach deposit, Binntal, Switzerland. The chemical formula of argentobaumhauerite, calculated in agreement with the results of structure determination is Cu0.06Ag1.20Tl0.18Pb21.46Sb0.56As32.28 S72.26. The difference from the idealized baumahuerite formula, Pb12As16S36, and from the formula of Ag – , Tl- and Sb-free baumhauerite from Moosegg, Austria, Pb11.80As16.28S35.92, expresses the Ag + As and Tl + As substitution for 2Pb. Argentobaumhauerite is triclinic, a = 7.9053(10), b = 8.4680(10), c = 44.4102(53) Å, α = 84.614(2), β = 86.469(2), γ = 89.810(2)°. V(cell) = 2954.16 Å3, space group P1. Baumhauerite Pb11.80As16.28S35.92 from Moosegg is triclinic, a = 7.884(4), b = 8.345(4), c = 22.811(11) Å, α = 90.069(8), β = 97.255(8), γ = 90.082(8)°, V(cell) = 1488.8(13) Å3, space group P1. Both minerals represent the N 1,2 = 3;4 = 3.5 member of the sartorite homologous series, with As-rich slabs separated by zigzag layers of trigonal coordination prisms of lead. In argentobaumhauerite the sequence of alternating N = 3 and N = 4 slabs of baumhauerite is further modified by alternation of two distinct types of N = 4 slabs, those with Pb present in the slab interior and those with the interior Pb substituted by Ag + As. The length and arrangement of crankshaft chains of short As–S bonds differs between different slabs, and especially between the N = 4 slabs of baumhauerite and argentobaumhauerite. The name 'argentobaumhauerite' replaces the preliminary name 'baumhauerite-2a' (IMA-CNMNC; accepted proposal 15-F).

Data for U, Th, and K, determined by neutron activation analysis, in 128 rock samples from 14 Irish Caledonian and Tertiary granite plutons are sum-marized. Irish Newer Caledonian granites (ninety-four samples) have values of radioelements (average 3.6 ppm U, 12.1 ppm Th, and 3.4% K) consistent with derivation from a source of broadly uniform composition. U mineralization occurs in the voluminous and forcefully emplaced Main Donegal and Leinster plutons whereas smaller passively emplaced granites (Galway, Barnesmore, Rosses) lack mineralization. Irish Tertiary granites (thirty-four samples), which represent small batches of highly fractionated acid magmas, show moderate or high radioelement contents (11.5 ppm U, 39.9 ppm Th, 4.5% K) but are not mineralized. It is concluded that the use of elevated radioelement contents as a criterion of granite ‘fertility’ may be misleading in the British Isles Caledonian Province. The radioelement chemistry of granites may reflect their source composition more closely than expected for differentiated and/or contaminated acid melts.

Hydrothermal synthesis produced the new compound SrCo2(AsO4)(AsO3OH)(OH)(H2O). The compound belongs to the tsumcorite group (natural and synthetic compounds with the general formula M(1)M(2)2(XO4)2(H2O,OH)2; M(1)1+,2+,3+ = Na, K, Rb, Ag, NH4, Ca, Pb, Bi, Tl; M(2)2+,3+ = Al, Mn3+, Fe3+, Co, Ni, Cu, Zn; and X5+,6+ = P, As, V, S, Se, Mo). It represents (1) the first Sr member, (2) the until now unknown [7]-coordination for the M(1) position, (3) the first proof of (partially) protonated arsenate groups in this group of compounds, and (4) a new structure variant.

The crystal structure of the title compound was determined using single-crystal X-ray diffraction data. The compound is monoclinic, space group P21/a, with a = 9.139(2), b = 12.829(3), c = 7.522(2) Å, β = 114.33(3)°, V = 803.6(3) Å3, Z = 4 [wR2 = 0.065 for 3530 unique reflections]. The hydrogen atoms were located experimentally.

A new occurrence of zaherite is reported from a sillimanite quarry 65 km west of Pofadder, Bushmanland, South Africa. It occurs as earthy white to light bluish-green cryptocrystalline material in narrow veins, in close association with natro-alunite and hotsonite, a new hydrated aluminium phosphate-sulphate. Scanning electron micrographs show an orientated wavy texture and tubular fibres. The optical and physical properties agree with those of the type material described from Pakistan, and it can be added that the mineral is biaxial positive with a moderate 2V and length-fast orientation. The new chemical analysis yields an ideal formula of Al12(SO4)5(OH)26·20H2O, which is identical to that of the type material. The white and light bluishgreen varieties are identical in major element composition but yielded trace Cu values of 1281 and 2408 ppm respectively. The X-ray powder diffraction pattern fits a triclinic symmetry (a 5.55, b 9.74, c 18.43Å, α 99.71°, β 89.13° γ 94.97°), and is dominated by one intense reflection at 18.12 Å, representing 001. The most important of the weak lines are (d, I, hkl): 9.56, 5, 010; 9.08, 4, 002; 4.82, 6, 01; 4.61, 8, 110; 4.56, 4, 02; 4.44, 4, 021; 3.61, 4, 1; 3.22, 8, 015. The differential thermal properties are characterized by endothermic peaks at 190, 470, and 685°C and a duplex at 880 and 910°C The infrared absorption spectrum is characterized by absorption bands centring about 905, 960, 985, 1150, 1700, and 3600 cm−1.

Kagomé nets of corner-connected triangles of atoms occur in diverse minerals, from the {111} anion arrays in perovskite-group minerals to natural metallic alloys like auricupride, AuCu3, to the cation layers in atacamite-group minerals. We review here two- and three-dimensional kagomé networks in minerals where the kagomé node atoms are octahedrally coordinated in hexagonal tungsten bronze (HTB) arrays. Octahedral tilting, coupled with capping of the apical anions of the triangular groupings of octahedra in the HTB layers, gives rise to several important mineral groups, including pyrochlores, alunite-supergroup minerals, zirconolite and weberite polytypes and spinel-group minerals, as a function of the magnitude and type of the octahedral tilting.

Bendadaite, ideally Fe2+Fe23+ (AsO4)2(OH)2·4H2O, is a new member of the arthurite group. It was found as a weathering product of arsenopyrite on a single hand specimen from the phosphate pegmatite Bendada, central Portugal (type locality). Co-type locality is the granite pegmatite of Lavra do Almerindo (Almerindo mine), Linópolis, Divino das Laranjeiras county, Minas Gerais, Brazil. Further localities are the Veta Negra mine, Copiapó province, Chile; Oumlil-East, Bou Azzer district, Morocco; and Pira Inferida yard, Fenugu Sibiri mine, Gonnosfanadiga, Medio Campidano Province, Sardinia, Italy.

Type bendadaite occurs as blackish green to dark brownish tufts (<0.1 mm long) and flattened radiating aggregates, in intimate association with an intermediate member of the scorodite–mansfieldite series. It is monoclinic, space group P21/c, with a = 10.239(3) Å, b = 9.713(2) Å, c = 5.552(2) Å, β = 94.11(2)°, V = 550.7(2) Å3, Z = 2. Electron-microprobe analysis yielded (wt.%): CaO 0.04, MnO 0.03, CuO 0.06, ZnO 0.04, Fe2O3 (total) 43.92, Al2O3 1.15, SnO2 0.10, As2O5 43.27, P2O5 1.86, SO3 0.03. The empirical formula is (Fe2+0.52Fe3+0.32☐0.16)Σ1.00(Fe3+1.89Al0.11)Σ2.00(As1.87P0.13)Σ2.00O8(OH)2.00·4H2O based on 2(As,P) and assuming ideal 8O, 2(OH), 4H2O and complete occupancy of the ferric iron site by Fe3+ and Al. Optically, bendadaite is biaxial, positive, 2Vest. = 85±4°, 2Vcalc. = 88°, with α 1.734(3), β 1.759(3), γ 1.787(4). Pleochroism is medium strong: X pale reddish brown, Y yellowish brown, Z dark yellowish brown; absorption Z > Y > X, optical dispersion weak, r > v. Optical axis plane is parallel to (010), with X approximately parallel to a and Z nearly parallel to c. Bendadaite has vitreous to sub-adamantine luster, is translucent and non-fluorescent. It is brittle, shows irregular fracture and a good cleavage parallel to {010}. Dmeas. 3.15±0.10 g/cm3, Dcalc. 3.193 g/cm3 (for the empirical formula). The five strongest powder diffraction lines [d in Å (I)(hkl)] are 10.22 (10)(100), 7.036 (8)(110), 4.250 (5)(111), 2.865 (4)(), 4.833 (3)(020,011). The d spacings are very similar to those of its Zn analogue, ojuelaite. The crystal structure of bendadaite was solved and refined using a crystal from the co-type locality with the composition (Fe2+0.95☐0.05)Σ1.00(Fe3+1.80Al0.20)Σ2.00(As1.48P0.52)Σ2.00O8(OH)2·4H2O (R = 1.6%), and confirms an arthurite-type atomic arrangement.

Fluoroleakeite, NaNa2(Mg2Fe3+2Li)Si8O22F2 is a new mineral of the amphibole group from the Verkhnee Espe deposit, Akjailyautas mountains, eastern Kazakhstan district, Kazakhstan. The granites and their host rocks have been intensely reworked by post-magmatic and host-rock fluids, resulting in intense recrystallization, enrichment in F, Li and rare elements, and replacement of primary biotite and sodic-calcic amphiboles by Li-bearing riebeckite, aegirine, astrophyllite and other sodic minerals including fluoroleakeite. Crystals are prismatic parallel to [001] with {100} and {110} faces and cleavage surfaces, and the prism direction is terminated by irregular fractures. Grains are up to 3 mm long, and occur as isolated crystals, as small aggregates, and as inclusions in cámaraite. Crystals are black with a very pale grey to colourless streak. Fluoroleakeite is brittle, has a Mohs hardness of 6 and a splintery fracture; it is non-fluorescent with perfect {110} cleavage, no observable parting, and has a calculated density of 3.245 g cm–3. In plane-polarized light, it is pleochroic, X = pale grey-green, Y = medium grey, Z = grey-brown; X^a = 14.1° (in β obtuse), Y ‖ b, Z^c = 75.9° (in β acute). Fluoroleakeite is biaxial negative, α = 1.663(2), β = 1.673(2), γ = 1.680(2); 2Vobs = 80.9(6)°, 2Vcalc = 79.4°

Fluoro-leakeite is monoclinic, space group C2/m, a = 9.8927(3), b = 17.9257(6), c = 5.2969(2) Å, β = 103.990(1)°, V = 905.7(1) Å3, Z = 2. The strongest ten X-ray diffraction lines in the powder pattern are [d in Å(I)(hkl)]: 2.718(100)(151), 8.434(40)(110), 4.464(30)(021), 3.405(30)(131), 3.137(20)(310), 2.541(20)(), 2.166(20)(261), 2.325(15)(), 2.275(15)() and 2.806(10)(330). Analysis by a combination of electron microprobe and crystal-structure refinement gives SiO2 53.34, Al2O3 0.62, TiO2 1.27, V2O3 0.05, Fe2O3 15.10, FeO 6.00, MnO 2.04, ZnO 0.18, MgO 6.40, CaO 0.13, Na2O 9.08, K2O 1.98, Li2O 1.10, F 3.33, H2Ocalc 0.16, sum 99.39 wt.%. The formula unit, calculated on the basis of 23 O, is A(Na0.64K0.38)(Na1.98Ca0.02)(Li0.66Mg1.42Fe0.752+Mn0.262+Zn0.02Fe1.693+V0.013+Ti0.144+Al0.03) (Si7.93Al0.07)O22(F1.57OH0.16O0.27). Crystal-structure refinement shows Li to be completely ordered at the M(3) site. Fluoroleakeite, ideally NaNa2(Mg2Fe23+Li)Si8O22F2, is related to end-member leakeite, NaNa2(Mg2Fe23+Li)Si8O22(OH)2 by the substitution F → (OH).

The new mineral bytízite was found in the dump of shaft No. 16, one of the mines in the Příbram uranium and base-metal district, central Bohemia, Czech Republic. Bytízite is associated with chaméanite, příbramite, giraudite, berzelianite, umangite, eskebornite, hakite, tetrahedrite, bukovite, crookesite and uraninite in a calcite-dominant gangue. The new mineral occurs as anhedral grains up to 40 µm, growing together in aggregates up to 300 µm across. Bytízite is steel-grey in colour and has a metallic lustre. Mohs hardness is ca. 2–3; the calculated density is 6.324 g cm–3. In reflected light bytízite is grey with a yellowish hue, yellowish and brownish. Bireflectance and pleochroism are weak. Anisotropy is strong with grey to brownish rotation tints. Internal reflections were not observed. The empirical formula, based on electron-microprobe analyses, is (Cu3.00Fe0.01Ag0.01)3.02(Sb0.97As0.06)1.03Se2.94. The ideal formula is Cu3SbSe3, which requires Cu 34.71, Sb 22.16 and Se 43.13, total 100.00 wt.%. Bytízite is orthorhombic, Pnma, a = 7.9594(12), b = 10.5830(14), c = 6.8240(11) Å, with V = 574.82(15) Å3 and Z = 4. The strongest reflections of the calculated powder X-ray diffraction pattern [d, Å (I)(hkl)] are: 3.73(37)(210), 3.27(62)(211), 2.867(40)(022), 2.698(100)(122) and 2.646(37)(040). According to the single-crystal X-ray diffraction data (Robs = 0.0437), bytízite is isostructural with synthetic Cu3SbSe3. The structure of bytízite contains two Cu, one Sb, and two Se sites (the latter is occupied both by Se and S atoms). In the structure of both synthetic Cu3SbSe3 and bytízite, there are groups of three cis-edge-sharing tetrahedra [Cu3Se8], which are interlinked to a 3D framework by SbSe3 groups. Bytízite is named after its type locality, the Bytíz deposit, near the village Bytíz.

The ideal end-members reddingite, Mn32+ H2 O)3(PO4)2, phosphoferrite, (H 2O)3(PO4)2, and kryzhanovskite, (OH)3(PO4)2 form a complex triple series. Similarities in crystal axes and pronounced differences in site preferences have led to erroneous indexing of the powder data and subsequent errors in cell refinements. Writing the general formula M(1)M(2)2[(H2O),(OH)]3(PO4)2, the following end-member names apply:

Type landesite,Ca0.4Mg1.2(OH)3.2(H2O)8.8(PO4)8.0, has a = 9.458(3) Å, b = 10.185(2) Å, c = 8.543(2) Å, space group Pbna. R = 5.2% for 1821 independent reflexions (Mo-Kα radiation). The distance averages are M(1)-O = 2.098 Å, M(2)-O = 2.205 Å, P-O = 1.539 Å. Cotype kryzhanovskite,Ca0.5Mg0.4(OH)7.3(H4O)4.7(PO4)8.0, has a = 9.450(2) Å, b = 10.013(2), c = 8.179(2). R = 7.2% for 1,703 independent reflexions (Mo-Kα radiation). The distance averages are M(1)-O = 2.017 Å, M(2)-O = 2.115, P-O = 1.542.

Computed powder pattern intensities from the structure data admitted extensive revisions of earlier published Miller indices and revised powder data are presented.

Nipalarsite, Ni8Pd3As4, is a new platinum-group mineral discovered in the sulfide-bearing orthopyroxenite of the Monchetundra layered intrusion, Kola Peninsula, Russia (67°52′22″N, 32°47′60″E). Nipalarsite forms anhedral grains (5–80 µm in size) in intergrowths with sperrylite, kotulskite, hollingworthite, isomertieite, menshikovite, palarstanide, nielsenite and monchetundtraite enclosed in pentlandite, anthophyllite, actinolite and chlorite. Nipalarsite is brittle, has a metallic lustre and a grey streak. In plane-polarised light, nipalarsite is light grey with a blue tinge. Reflectance values in air (in %) are: 46.06 at 470 nm, 48.74 at 546 nm, 50.64 at 589 nm and 54.12 at 650 nm. Values of VHN20 fall between 400.5 and 449.2 kg.mm–2, with a mean value of 429.9 kg.mm–2, corresponding to a Mohs hardness of ~4. The average result of 27 electron microprobe wavelength dispersive spectroscopy analyses of nipalarsite is (wt.%): Ni 44.011, Pd 28.74, Fe0.32, Cu 0.85, Pt 0.01, Au 0.05, As 25.42, Sb 0.05, Te 0.39, total 99.85. The empirical formula (normalised to 15 atoms per formula unit) is: (Ni8.10Fe0.06)Σ8.16(Pd2.94Cu0.18)Σ3.12(As3.68Te0.03)Σ3.71 or, ideally, Ni8Pd3As4. Nipalarsite is cubic, space group Fm$\bar{3}$m, with a = 11.4428(9) Å, V = 1498.3(4) Å3 and Z = 8. The strongest lines in the powder X-ray diffraction pattern of synthetic Ni8Pd3As4 [d, Å (I) (hkl)] are: 2.859(10)(004), 2.623(6)(313), 2.557(6)(024), 2.334(11)(224), 2.201(35)(115,333), 2.021(100)(044), 1.906(8)(006,244) and 1.429(7)(008). The crystal structure was solved and refined from the single-crystal X-ray diffraction data of synthetic Ni8Pd3As4. The relation between natural and synthetic nipalarsite is illustrated by an electron back-scattered diffraction study of natural nipalarsite. The density calculated on the basis of the empirical formula of nipalarsite is 9.60 g.cm–3. The mineral name corresponds to the three main elements: Ni, Pd and As.

The crystal chemistry of wavellite from Zbirov (Czech Republic), ideally Al3(PO4)2(OH,F)3·5H2O, was addressed by means of a multi-methodological approach based on electron microprobe analysis (EMPA) using wave-dispersive spectroscopy, single-crystal X-ray diffraction, powder and singlecrystal infrared spectroscopy and Raman spectroscopy. The EMPA data showed the presence of significant F replacing OH in the sample studied. The structure was solved in the Pcmn orthorhombic space group, with the following unit-cell constants: a = 9.6422(7), b = 17.4146(15), c = 7.0094(2) Å, V = 1176.98(10) Å3. Phosphorus atoms display tetrahedral (PO4) coordination, while Al cations display octahedral coordination. The mineral framework can be viewed as the repetition of cationic arrays made up of AlO6 polyhedra, bridged by PO4 groups and further joined by O–H⋯O hydrogen bonds. The single-crystal unpolarized Fourier transform infrared (FTIR) spectrum shows combination bands indicating the presence of both OH and H2O in the structure. Both FTIR and Raman spectra show a broad absorption extending from 3600 to 2800 cm−1 resulting from the overlapping of several components due to the water molecules and the OH group. The frequencies observed are comparable to those expected on the basis of the Libowitzky relationship for the range of D–H⋯A bond systems in the structure.

In clinopyroxene-melt systems the distribution of chromium and vanadium ions departs from the general pattern of element partition as a function of ionic radius. These departures may be explained by crystal-field effects. Melt structure and the nature of the coordination of cations in the melt also help to determine the pattern of distribution and the extent of the departures from regularity.

Extensive substitution of Ni for Zn in hydrozincite from the Parc Mine, North Wales, has been observed. This is the first time that a substantial concentration of another transition metal in this mineral has been reported. The average composition of the nickeloan hydrozincite is Zn4.63Ni0.37(CO3)2(OH)6. The relationship of this new variety to other secondary carbonate-containing nickel minerals is discussed, as is the possibility of substitution of other transition metal ions into the hydrozincite lattice.

Putnisite, SrCa4Cr83+ (CO7)8SO4(OH)16·25H2O, is a new mineral from the Polar Bear peninsula, Southern Lake Cowan, Western Australia, Australia. The mineral forms isolated pseudocubic crystals up to 0.5 mm in size in a matrix composed of quartz and a near amorphous Cr silicate. Putnisite is translucent, with a pink streak and vitreous lustre. It is brittle and shows one excellent and two good cleavages parallel to {100}, {010} and {001}. The fracture is uneven and the Mohs hardness 1½−2. The measured density is 2.20(3) g/cm3 and the calculated density based on the empirical formula is 2.23 g/cm3. Optically, putnisite is biaxial negative, with α = 1.552(3), β = 1.583(3) and γ = 1.599(3) (measured in white light). The optical orientation is uncertain and pleochroism is distinct: X pale bluish grey, Y pale purple, Z pale purple. Putnisite is orthorhombic, space group Pnma, with a = 15.351(3), b = 20.421(4) Å, c = 18.270(4) Å, V = 5727(2) Å3 (single-crystal data), and Z = 4. The strongest five lines in the X-ray powder diffraction pattern are [d(Å)(I)(hkl)]: 13.577 (100) (011), 7.659 (80) (200), 6.667 (43) (211), 5.084 (19) (222, 230), 3.689 (16) (411). Electron microprobe analysis (EMPA) gave (wt.%): Na2O 0.17, MgO 0.08, CaO 10.81, SrO 5.72, BaO 0.12, CuO 0.29, Cr2O3 31.13, SO3 3.95, SiO2 0.08, Cl− 0.28, CO2calc 17.94, H2Ocalc 30.30, O=Cl−0.06, total 100.81. The empirical formula, based on O + Cl = 69, is: Cr8.023+Ca3.78Sr1.08Na0.11Cu0.072+Mg0.04Ba0.02[(SO4)0.96(SiO4)0.03]0.99 (CO3)7.98(OH)16.19Cl0.15·24.84H2O. The crystal structure was determined from single-crystal X-ray diffraction data (MoKα, CCD area detector and refined to R1 = 5.84% for 3181 reflections with F0 > 4σF. Cr(OH)4O2 octahedra link by edge-sharing to form an eight-membered ring. A 10-coordinated Sr2+ cation lies at the centre of each ring. The rings are decorated by CO3 triangles, each of which links by corner-sharing to two Cr(OH)4O2 octahedra. Rings are linked by Ca(H2O)4O4 polyhedra to form a sheet parallel to (100). Adjacent sheets are joined along [100] by corner-sharing SO4 tetrahedra. H2O molecules occupy channels that run along [100] and interstices between slabs. Moderate to weak hydrogen bonding provides additional linkage between slabs.