Non-stoichiometric, carbon-containing crandallite from Guatemala and plumbogummite from Cumbria have been characterized using electron microprobe (EMPA) and wet-chemical analyses, Rietveld analysis of powder X-ray diffraction (PXRD) patterns, and infrared (IR), Raman and cathodoluminescence (CL) spectroscopies. The samples contain 11.0 and 4.8 wt.% CO2, respectively. The IR spectra for both samples show a doublet in the range 1410–1470 cm–1, corresponding to CO3 vibrations. Direct confirmation of CO3 replacing PO4 was obtained from difference Fourier maps in the Rietveld analysis. Carbonate accounts for 67% of the C in the plumbogummite and 20% of the C in the Guatemalan crandallite, the remainder being present as nano-scale organic carbon. The CO3 substitution for PO4 is manifested in a large contraction of the tetrahedral volume (14–19%) and by a contraction of the a axis, analogous to observations for carbonate-containing fluorapatites. Stoichiometric crandallite from Utah was characterized using the same methods, for comparison with the non-stoichiometric, carbon-bearing phases.

Nordgauite, MnAl2(PO4)2(F,OH)2·5H2O, is a new secondary phosphate from the Hagendorf-Süd pegmatite, Bavaria, Germany. It occurs as white to off-white compact waxy nodules and soft fibrous aggregates a few millimetres across in altered zwieselite—triplite. Individual crystals are tabular prismatic, up to 200 μ long and 10 μ wide. Associated minerals include fluorapatite, sphalerite, uraninite, a columbite—tantalite phase, metastrengite, several unnamed members of the whiteite—jahnsite family, and a new analogue of kingsmountite. The fine-grained nature of nordgauite meant that only limited physical and optical properties could be obtained; streak is white; fracture, cleavage and twinning cannot be discerned. Dmeas. and Dcaic. are 2.35 and 2.46 g cm–3, respectively; the average RI is n = 1.57; the Gladstone-Dale compatibility is —0.050 (good). Electron microprobe analysis gives (wt.%): CaO 0.96. MgO 0.12, MnO 14.29, FeO 0.60, ZnO 0.24, A12O3 22.84, P2O5 31.62, F 5.13 and H2O 22.86 (by CHNX less F=O 2.16, total 96.50. The corresponding empirical formula is (Mn0.90Ca0.08Fe0.04Zn0.01Mg0.01)-Σi.04Ai2.0i(PO4)2[F1.21,(OH)0.90]Σ2.11·5.25H2O. Nordgauite is triclinic, space group P1̄, with the unit-cell parameters: a = 9.920(4), b = 9.933(3), c = 6.087(2) Å, α = 92.19(3), β = 100.04(3), γ = 97.61(3)°, V = 584.2(9) Å3 and Z = 2. The strongest lines in the XRD powder pattern are [d in Å (I) (hkl)] 9.806 (100)(010), 7.432 (40)(l1̄0), 4.119 (20)(210), 2.951 (16)(031), 4.596 (12)(21̄O), 3.225 (12)(220) and 3.215 (12)(121). The structure of nordgauite was solved using synchrotron XRD data collected on a 60 μm × 3 μm × 4 μm needle and refined to R1 = 0.0427 for 2374 observed reflections with F > 4σ(F). Although nordgauite shows stoichiometric similarities to mangangordonite and kastningite, its structure is more closely related to those of vauxite and montgomeryite in containing zig-zag strings of corner-connected Al-centred octahedra along [011], where the shared corners are alternately in cis and trans configuration. These chains link through corner-sharing with PO4 tetrahedra along [001] to form (100) slabs that are interconnected via edge-shared dimers of MnO6 polyhedra and other PO4 tetrahedra.

Angastonite, ideally CaMgAl2(PO4)2(OH)4-7H2O, is a newly defined mineral from the Penrice marble quarry, South Australia. The mineral occurs as snow-white crusts and coatings up to ∼1 mm thick associated with minyulite, perhamite, crandallite and apatite-(CaF). The streak is white, the lustre is pearly and the estimated hardness is 2 on the Mohs scale. Angastonite forms platy crystals with the forms {010} (prominent), {101}, {101} and {100} (rare), and also occurs as replacements of an unknown pre-existing mineral. There is one cleavage direction on ﹛010} and no twinning has been observed. Angastonite is triclinic, P1̄, with a = 13.303(1) Å, b = 27.020(2) Å, c = 6.1070(7) Å α = 89.64(1)°, β = 83.44(1)°, γ = 80.444(8)°, V = 2150.5(4) Å3, with Z = 6. The mineral is optically biaxial (+), with refractive indices of α = 1.566(2), β = 1.572(2) and γ 1.584(2) and with 2Vmeas = 70(2)° and 2Vcalc = 71°. Orientation: X ≈ a, Y ≈ b, Z ≈ c; with crystals showing parallel extinction and no axial dispersion. Dmeas is 2.47 g/cm3, whilst Dcalc is 2.332 g/cm3. The strongest four powder-diffraction lines [d in Å, (I/I°), hkl] are: 13.38, (100), 020; 11.05, (25), 11̄0; 5.73, (23), 101, 230 and 111; 8.01, (21), 130. Angastonite is likely to be related to the montgomeryite-group members and have a similar crystal structure, based on slabs of phosphate tetrahedra and Al octahedra.

Kintoreite is a new lead iron phosphate mineral in the alunite-jarosite family, from Broken Hill, New South Wales, Australia. It is the phosphate analogue of segnitite and the iron analogue of plumbogummite. Kintoreite occurs as clusters and coatings of cream to yellowish green rhombohedral crystals up to 2 mm high and with the principal form {112}. The mineral also forms waxy, yellowish green globular crusts and hemispheres on other phosphate minerals. These associated species include pyromorphite, libethenite, rockbridgeite/dufrenite, apatite and goethite. Kintoreite formed during oxidation of primary ore rich in galena, in the presence of solutions with high P/(As + S) ratios. The mineral is named for the locality, the Kintore opencut, in which it is most common. A mineral closely resembling kintoreite in composition has also been found at several mines in Germany. Type material is preserved in the Museum of Victoria and the South Australian Museum.

Electron microprobe analysis showed a nearly complete spread of compositions across the P-dominant portion of the segnitite-kintoreite series. The selected type specimen has an empirical formula of Pb0.97(Fe2.95Zn0.13Cu0.02)Σ3.10[(PO4)1.30(AsO4)0.39(SO4)0.18(CO3)0.11]Σ1.98(OH)5.45·0.74H2O, calculated on the basis of 14 oxygens and with all Fe trivalent. The simplified formula is PbFe3(PO4)2(OH,H2O)6. Kintoreite crystals are translucent with a vitreous to adamantine lustre, with globules appearing waxy. The streak is pale yellowish green and the Mohs hardness is ∼ 4. Crystals show good cleavage on {001} and are brittle with a rough fracture. The calculated density is 4.34 g cm−3. Kintoreite crystals are uniaxial negative with RIs between 1.935 and 1.955 and show light yellowish green to medium yellow pleochroism.

The strongest lines in the X-ray powder pattern are (dobs, Iobs, hkl) 3.07(100) 113; 5.96(90)101; 3.67(60)110; 2.538(50)024; 2.257(50)107; 1.979(50)303; 1.831(40)220. The X-ray data were indexed on a hexagonal unit cell by analogy with beudantite, giving a = 7.325(1) Å, c = 16.900(3) Å, V = 785.3(5) Å3 and Z = 3. The probable space group is Rm, by analogy with beudantite and other members of the alunite-jarosite family. Powder X-ray diffraction data for several intermediate members suggest that the segnitite-kintoreite series may not represent ideal solid solution.

During the study of kintoreite, part of the type specimen of lusungite from Zaïre was obtained and shown to be goyazite. The IMA's Commission on New Minerals and Mineral Names has voted to discredit lusungite as a species, and has approved the renaming of the ‘lusungite’ group as the segnitite group. However, as relationships between crystal structure, order-disorder and solid solution in the Pb-rich minerals of the alunite-jarosite family are not well documented, the nomenclatural changes resulting from this study should be seen as interim only.

The introduction of a fifth amphibole group, the Na-Ca-Mg-Fe-Mn-Li group, defined by 0.50 < B(Mg,Fe2+,Mn2+,Li) < 1.50 and 0.50 ≤ B(Ca,Na) ≤ 1.50 a.f.p.u. (atoms per formula unit), with members whittakerite and ottoliniite, has been required by recent discoveries of B(LiNa) amphiboles. This, and other new discoveries, such as sodicpedrizite (which, here, is changed slightly, but significantly, from the original idealized formula), necessitate amendments to the IMA 1997 definitions of the Mg-Fe-Mn-Li, calcic, sodic-calcic and sodic groups. The discovery of obertiite and the finding of an incompatibility in the IMA 1997 subdivision of the sodic group, requires further amendments within the sodic group. All these changes, which have IMA approval, are summarized.

The type specimen of peisleyite has been reinvestigated by a combination of scanning electron microscopy, electron probe microanalysis (EPMA) and synchrotron powder X-ray diffraction. Morphological investigation showed that mats of peisleyite crystals, individually <3 μm across, are intergrown with wavellite veinlets to form the white cryptocrystalline material that is typical of ‘peisleyite’. New EPMA data (mean of 12 analyses) gave the empirical formula of peisleyite as (Na1.69Ca0.18)Σ1.87(Al9.04Fe0.03)Σ9.07[(P6.28S1.38Si0.25)O4]Σ7.91(OH)6.66·27.73H2O, or ideally Na2Al9[(P,S)O4]8(OH)6·28H2O. The associated wavellite was found to be F-rich. Synchrotron powder data were indexed and refined and gave the following unit cell: P1̄, a = 9.280(19), b = 11.976(19), c = 13.250(18) Å, α = 91.3(1), β = 75.6(1), γ = 67.67(1)°, V = 1308(5) Å3 and Z = 4. These data are significantly different to those reported in the original description of peisleyite.

Bariosincosite is a new barium vanadium phosphate hydrate from the Spring Creek Mine, near Wilmington, South Australia. The new mineral occurs as irregular clusters of pale green, very thin platey crystals up to 250 µm across and 2 to 5 µm thick. The tetragonal crystals are tabular on {001} and the other form present is {100}. Associated with bariosincosite are quartz, cuprite, native copper, fluorapatite, whitlockite, baryte and springcreekite, BaV33+ (PO4)2(OH,H2O)6. Bariosincosite appears to have formed under supergene or low-temperature late-stage hydrothermal conditions. Electron microprobe analysis yielded: BaO 23.20; SrO 4.19; CaO 0.36; VO2 31.55; Fe2O3 0.20; Al2O3 0.50; P2O5 28.15; H2O 13.93 (calculated). These data give an empirical formula of (Ba0.77Sr0.20Ca0.03)∑1.00[(V0.964+ Al0.03Fe0.013+)∑1.00O(PO4)]2·4H2O, calculated on the basis of two P atoms. The simplified formula is Ba(V4+OPO4)2·4H2O. The mineral is transparent with a very pale green streak, a vitreous lustre and an estimated Mohs hardness of 3. The strongest lines in the X-ray powder pattern are [dobs (Iobs) (hkl)] 6.414 (20) (110, 002); 5.748 (70) (111); 4.552 (30) (112, 200); 3.198 (20) (220, 004); 3.100 (100) (203, 221); 2.847 (40) (222, 114); 2.786 (80) (311); 2.368 (30) (313, 115); and 2.017 (100) (420, 332, 116). These data were indexed on a tetragonal cell, with a = 9.031(6), c = 12.755(8) Å and V = 1040(1) Å3; the space group is probably P4/n or P4/nmm. For Z = 4 and using the empirical formula, the calculated density is 3.306 gm/cm3. Bariosincosite is uniaxial negative with ω = 1.721(2) and ε = 1.715(2) (white light); pleochroism is weak from colourless (E) to pale green (O), absorption O > E. The mineral is named for the relationship to sincosite, Ca(V4+OPO4)2·4H2O.

Type specimens of the molybdoarsenates betpakdalite, natrobetpakdalite and obradovicite and the molybdophosphates mendozavilite, paramendozavilite and melkovite, and similar material from other sources, have been examined in an effort to elucidate the relations among these phases, which we designate as the heteropolymolybdate family of minerals. Using electron microprobe analysis, X-ray powder diffraction and single-crystal X-ray diffraction with crystal structure determination where possible, it was found that natrobetpakdalite, mendozavilite and melkovite are isostructural with betpakdalite and that obradovicite has a closely related structure.

The betpakdalite and obradovicite structure types are based on frameworks containing four-member clusters of edge-sharing MoO6 octahedra that link by sharing corners with other clusters, with Fe3+O6 octahedra and with PO4 or AsO4 tetrahedra (T). The structures differ in the linkages through the Fe3+O6 octahedra, which produce different but closely related framework configurations. The structures contain two types of non-framework cation sites, which are designated A and B. In general, there are two or more A sites partially occupied by disordered, generally larger cations that are coordinated to O atoms in the framework and to H2O molecules. The B site is occupied by a smaller cation that is octahedrally coordinated to H2O molecules. The general formula for minerals with either the betpakdalite or the obradovicite structure is: [A2(H2O)nB(H2O)6][Mo8T2Fe3+3O30+7(OH)7–x], where x is the total charge of the cations in the A and B sites (+3 to +7) and n is variable, ideally 17 for arsenates and 15 for phosphates. The ideal total number of A cations is defined as 2 in the general formula, but varies from 1 to 3.8 in analysed samples. Dominant cations at the A site include K, Na and Ca and at the B site Na, Ca, Mg, Cu and Fe. The combinations that have been identified in this study define six new heteropolymolybdate species.

A suffix-based nomenclature scheme is established for minerals of the betpakdalite, mendozavilite and obradovicite groups, with the following root names based on the structure types and the T-site cations: betpakdalite (T = As), mendozavilite (T = P) and obradovicite (T = As). Two suffixes of the form -AB, corresponding to the dominant cations in the two different types of non-framework cation sites complete the species name. The historical name melkovite is retained rather than introducing mendozavilite-CaCa.

Our investigation of the paramendozavilite type specimen revealed no paramendozavilite, but an apparently closely related new mineral; however, another sample of paramendozavilite analysed had K > Na.

Sieleckiite is a new copper aluminium phosphate discovered at the Mt Oxide Copper Mine, 150 km north of Mt Isa, Queensland, Australia. It occurs with variscite, turquoise, libethenite and minor pseudomalachite in a fracture in a boulder of quartzite and shale. Sieleckiite forms deep sky blue to royal blue spheres up to 0.5 mm in diameter, made up of fibrous radiating crystals between 20 and 100 µm long and 1 to 2 µm wide. The mineral has a very pale blue streak and a pearly lustre on uneven fracture surfaces. Hardness is about 3 and the measured density is 3.02 g cm−3. The average of nine electron microprobe analyses gave CuO 32.39, Al2O3 26.57, P2O5 19.42%. Separate analyses gave H2O 18.1, CO2 1.6% (carbonate impurity). These data gave an empirical formula of Cu3.1Al4.0(PO4)2.1(OH)12.1.7H2O, calculated on the basis of 22 oxygen atoms. The simplified formula is Cu3Al4.0(PO4)2.1(OH)12.2H2O. The strongest lines in the X-ray powder diffraction pattern are {d(I)(hkl)}; 9.12(50)(100), 5.06(100)(101), 3.852(100)(111), 3.276(30)(2¯20), 2.827(50)(1¯02,102), 2.460(50)(3¯21). These data were indexed on a triclinic cell with a 9.41(8), b 7.56(5), c 5.95(6) Å, α 90.25(12)° β 91.27(12)° γ 104.02(7)° and a volume of 410.8(5) Å3. For Z = 1, the calculated density is 2.94 g cm−3. Optical properties could not be determined in full; the refractive indices are between 1.63 and 1.66, pleochroism is very weak from colourless to very pale blue.

The mineral is named for the discoverer, Robert Sielecki (1958- ). Type specimens are preserved at the Museum of Victoria and the South Australian Museum. Sieleckiite was approved by the IMA Commission on New Minerals and Mineral Names prior to publication.

A rich vein of silver and silver-lead sulphosalt minerals was discovered in 1906 in the Meerschaum Mine, on the Sunnyside goldfield at Mt. Wills, in northeastern Victoria. Andorite, miargyrite, tetrahedrite (freibergite), owyheeite, and argentian gold are the main silver-bearing minerals present, and sphalerite, pyrite, arsenopyrite, and covelline also occur in the vein.

The vein was probably emplaced under epithermal conditions from ore fluids accompanying the intrusion of the Mt. Wills granite. The main silver-bearing minerals were probably deposited at temperatures ranging from about 350 ° to below 300 °C.

Two new minerals – manganoblödite (IMA2012–029), ideally Na2Mn(SO4)2·4H2O, and cobaltoblödite (IMA2012–059), ideally Na2Co(SO4)2·4H2O, the Mn-dominant and Co-dominant analogues of blödite, respectively, were found at the Blue Lizard mine, San Juan County, Utah, USA. They are closely associated with blödite (Mn-Co-Ni-bearing), chalcanthite, gypsum, sideronatrite, johannite, quartz and feldspar. Both new minerals occur as aggregates of anhedral grains up to 60 μm (manganoblödite) and 200 μm (cobaltoblödite) forming thin crusts covering areas up to 2 × 2 cm on the surface of other sulfates. Both new species often occur as intimate intergrowths with each other and also with Mn-Co-Ni-bearing blödite. Manganoblödite and cobaltoblödite are transparent, colourless in single grains and reddish-pink in aggregates and crusts, with a white streak and vitreous lustre. Their Mohs' hardness is ∼2½. They are brittle, have uneven fracture and no obvious parting or cleavage. The measured and calculated densities are Dmeas = 2.25(2) g cm−3 and Dcalc = 2.338 g cm−3 for manganoblödite and Dmeas = 2.29(2) g cm−3 and Dcalc = 2.347 g cm−3 for cobaltoblödite. Optically both species are biaxial negative. The mean refractive indices are α = 1.493(2), β = 1.498(2) and γ = 1.501(2) for manganoblödite and α = 1.498(2), β = 1.503(2) and γ = 1.505(2) for cobaltoblödite. The chemical composition of manganoblödite (wt.%, electron-microprobe data) is: Na2O 16.94, MgO 3.29, MnO 8.80, CoO 2.96, NiO 1.34, SO3 45.39, H2O (calc.) 20.14, total 98.86. The empirical formula, calculated on the basis of 12 O a.p.f.u., is: Na1.96(Mn0.44Mg0.29Co0.14Ni0.06)Σ0.93S2.03O8·4H2O. The chemical composition of cobaltoblödite (wt.%, electron-microprobe data) is: Na2O 17.00, MgO 3.42, MnO 3.38, CoO 7.52, NiO 2.53, SO3 45.41, H2O (calc.) 20.20, total 99.46. The empirical formula, calculated on the basis of 12 O a.p.f.u., is: Na1.96(Co0.36Mg0.30Mn0.17Ni0.12)Σ 0.95S2.02O8·4H2O. Both minerals are monoclinic, space group P21/a, with a = 11.137(2), b = 8.279(1), c = 5.5381(9) Å, β = 100.42(1)°, V = 502.20(14) Å3 and Z = 2 (manganoblödite); and a = 11.147(1), b = 8.268(1), C = 5.5396(7) Å, β = 100.517(11)°, V = 501.97(10) Å3 and Z = 2 (cobaltoblödite). The strongest diffractions from X-ray powder pattern [listed as (d,Å(I)(hkl)] are for manganoblödite: 4.556(70)(210, 011); 4.266(45)(01); 3.791(26)(11); 3.338(21)(310); 3.291(100)(220, 021), 3.256(67)(211, 21), 2.968(22)(21), 2.647(24)(01); for cobaltoblödite: 4.551(80)(210, 011); 4.269(50)(01); 3.795(18)(11); 3.339(43)(310); 3.29(100)(220, 021), 3.258(58)(11, 21), 2.644(21)(01), 2.296(22)(122). The crystal structures of both minerals were refined by single-crystal X-ray diffraction to R1 = 0.0459 (manganoblödite) and R1 = 0.0339 (cobaltoblödite).

Small crystals of babingtonite and rare sphene occur in a coarse-grained aggregate of fluorapophyllite, stilbite, and calcite, infilling a late-stage cavity in granodiorite from Harcourt, Victoria. This is the first reported occurrence of babingtonite in Victoria. The assemblage crystallized from fluids in which Ca and F were significant and under P–T conditions of the order of 0.5 kbar, 100–150°C. Some of the fluorapophyllite has been altered to opaline silica suggesting that the residual solutions were acidic.

A calcium-rich ralstonite, forming colourless octahedral crystals up to 2 mm across, occurs in a F-rich assemblage at the Cleveland Mine, northwestern Tasmania. Other minerals present include well-crystallized morinite, gearksutite, vivianite, siderite, K-rich feldspar (adularia), fluorite and quartz. The F-rich assemblage probably formed during greisenization when Na and F-rich magmatic brines reacted with enclosing carbonate host rocks to produce hydrothermal Na-Ca-Mg-bearing solutions. Chemical analysis of the ralstonite-like mineral gave a formula (Na1.47Ca0.52)(Mg1.49Al0.55P0.04)F6 [(OH)0.43O0.36F0.21)].

This differs from the ‘pyrochlore’ formula, due to the substitution of Ca + (OH,O,F) for H2O, in addition to the coupled substitution of Na + Mg for Al in ‘normal’ ralstonites. The Cleveland Mine ralstonite has the highest recorded Ca, Na and Mg contents. While the mineral is likely to be a new species on chemical grounds, single crystal X-ray photographs indicate the structure is disordered, possibly composed of small compositional domains.

Shannonite, ideally Pb2OCO3, is a new mineral species that occurs as mm-sized white porcellanous crusts, associated with fluorite, at the Grand Reef mine, Graham County, Arizona, USA. Other associated minerals are plumbojarosite, hematite, Mn-oxides, muscovite-2M1, quartz, litharge, massicot, hydrocerussite, minium, and unnamed PbCO3·2PbO. Shannonite is orthorhombic, space group P21221 or P212121, with unit-cell parameters (refined from X-ray powder data): a 9.294(3), b 9.000(3), c 5.133(2) Å, V 429.3(3) Å3, a:b:c 1.0327:1:0.5703, Z = 4. The strongest five lines in the X-ray powder pattern [d in Å (I)(hkl)] are: 4.02(40)(111); 3.215(100)(211); 3.181(90)(121); 2.858(40)(130); 2.564(35)(002). The average of eight electron microprobe analyses is PbO 89.9(5), CO2 (by CHN elemental analyser) 9.70, total 99.60 wt.%. With O = 4, the empirical formula is Pb1.91C1.05O4.00. The calculated density for the empirical formula is 7.31 and for the idealized formula is 7.59 g/cm3. In reflected light, shannonite is colourless-grey to white, with ubiquitous white internal reflections (× 16 objectives), weak anisotropy, barely detectable bireflectance, and no evidence of pleochroism. The calculated refractive index (at 590 nm) is 2.09. Measured reflectance values in air and in oil (× 4 objectives) are tabulated. Transmission electron-microscopy studies reveal that individual crystallites range in size from 10–400 nm, are platy, and are anhedral. Physical properties for cryptocrystalline crusts include: white streak; waxy lustre; opaque; nonfluorescent under both long- and short-wave ultraviolet light; uneven fracture; brittle; VHN100 97 (range 93–100); calculated Mohs’ hardness 3–3½. Shannonite is soluble in concentrated HCl and in dilute HNO3 and H2SO4. The mineral name is for David M. Shannon, who helped collect the samples and who initiated this study.

Iangreyite, ideally Ca2Al7(PO4)2(PO3OH)2(OH,F)15·8H2O, is a new mineral (IMA2009-087) from the Silver Coin mine, Nevada, USA and the Krásno ore district, Horní Slavkov, Czech Republic. At Silver Coin, iangreyite occurs as thin, colourless to white or cream, hexagonal tablets up to 0.4 mm in diameter and 0.02 mm thick associated with meurigite-Na, plumbogummite, kidwellite, lipscombite. strengite, chalcosiderite, wardite, leucophosphite, wavellite, goethite, barite, quartz and F-rich perhamite. At Krásno, white, yellowish or light pink iangreyite coatings consist of 0.3 mm wide clusters of minute and very thin intergrown tabular crystals with a maximum diameter of 0.2 mm. Individual iangreyite crystals are transparent with a vitreous lustre, while iangreyite clusters tend to be pearly and translucent. The estimated hardness is 3 on the Mohs scale, the fracture is irregular and the mineral is non-fluorescent under SW and LW ultraviolet light. Individual crystals are somewhat flexible and there is perfect cleavage on ﹛001﹜. The density (Silver Coin), measured by the sink-float method in an aqueous solution of sodium polytungstate, is 2.46(3) g/cm3, while the calculated density is 2.451 g/cm3. Crystals from Silver Coin are uniaxial (+), with the indices of refraction: ε = 1.544(2) and s = 1.554(2), measured in white light, and are non-pleochroic. The empirical formula for iangreyite from Silver Coin (calculated on the basis of 39 anions per formula unit) is: Ca1.42K0.22Na0.09Ba0.03 Sr0.01Al6.51Mg0.09Fe0.02Cu0.01Zn0.01P3.81F5.24H30.21O33.76, while the empirical formula from Krásno is: Ca2.15K0.10Na0.01Ba0.02Sr0.12Al6.28Mg0.01Fe0.12Cu0.08Zn0.01P3.64Si0.43F4.65H29.62O34.35. Iangreyite is trigonal, space group P321 and Z = 1, with the unit-cell parameters (Silver Coin): a = 6.988(1), c = 16.707(3) Å and V= 706.5(2) Å3 and (Krasno): a = 6.989(1), c = 16.782(4) Å and V = 709.8(2) Å3. The structure of iangreyite, modelled from powder data, consists of blocks of the crandallite-type structure that are interconnected along c via corner-sharing of crandallite-block PO4 tetrahedra with A1O2(OH)3 bipyramids. This linkage generates large channels along [110] bounded by 10-member rings of octahedra, tetrahedra and trigonal biyramids, that are occupied by Ca and water molecules.

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.