Search

The crystal structure of vanthoffite {hexa­sodium magnesium tetra­kis[sulfate­(VI)]}, Na6Mg(SO4)4, was solved in the year 1964 on a synthetic sample [Fischer & Hellner (1964). Acta Cryst. 17, 1613]. Here we report a redetermination of its crystal structure on a mineral sample with improved precision. It was refined in the space group P21/c from a crystal originating from Surtsey, Iceland. The unique Mg (site symmetry 1̅) and the two S atoms are in usual, only slightly distorted octa­hedral and tetra­hedral coordinations, respectively. The three independent Na atoms are in a distorted octa­hedral coordination (1×) and distorted 7-coordinations inter­mediate between a `split octa­hedron' and a penta­gonal bipyramid (2×). [MgO6] coordination polyhedra inter­change with one half of the sulfate tetra­hedra in <011> chains forming a (100) meshed layer, with dimers formed by edge-sharing [NaO7] polyhedra filling the inter­chain spaces. The other [NaO7] polyhedra are organized in a parallel layer formed by [010] and [001] chains united through edge sharing and bonds to the remaining half of sulfate groups and to [NaO6] octa­hedra. The two types of layers inter­connect through tight bonding, which explains the lack of morphological characteristics typical of layered structures. [ABSTRACT FROM AUTHOR]

Eckerite, ideally Ag2CuAsS3, is a new mineral from the Lengenbach quarry in the Binn Valley, Valais, Switzerland. It occurs as very rare euhedral crystals up to 300 mm across associated with realgar, sinnerite, hatchite, trechmannite and yellow, fibrous smithite. In thick section eckerite is opaque with a metallic lustre and shows a dark orange-red streak. It is brittle; the Vickers hardness (VHN25) is 70 kg/mm2 (range: 64-78) (Mohs hardness of ~2½-3). In reflected light, eckerite is moderately bireflectant and weakly pleochroic from light grey to a slightly bluish grey. Internal reflections are absent. Under crossed nicols, it is weakly anisotropic with greyish to light blue rotation tints. Reflectance percentages for Rmin and Rmax are 27.6, 31.7 (471.1 nm), 22.8, 26.1 (548.3 nm), 21.5, 24.5 (586.6 nm) and 19.4, 22.3 (652.3 nm), respectively. Eckerite is monoclinic, space group C2/c, with a = 11.8643(3), b = 6.2338(1), c = 16.6785(4) Å , β = 110.842(3)º, V = 1152.81(5) Å3, Z = 8. The crystal structure [R1 = 0.0769 for 1606 reflections with Fo > 4σ(Fo)] is topologically identical to that of xanthoconite and pyrostilpnite. In the structure, AsS3 pyramids are joined by AgS3 triangles to form double sheets parallel to (001); the sheets are linked by Cu(Ag) atoms in a quasi-tetrahedral coordination. Among the three metals sites, Ag2 is dominated by Cu. The mean metal-S distances reflect well the Ag ↔ Cu substitution occurring at this site. The eight strongest powder X-ray diffraction lines [d in Å (I/I0) (hkl)] are: 3.336 (70) (3̅12); 2.941 (100) (3̅14,114); 2.776 (80) (400,2̅06); 2.677 (40) (312); 2.134 (50) (4̅21); 2.084 (40) (2̅08,206); 2.076 (40) (420); 1.738 (40) (2̅28,226). A mean of five electron microprobe analyses gave Ag 52.08(16), Cu 11.18(9), Pb 0.04(1), Sb 0.29(3), As 15.28(11), S 20.73(13), total 99.60 wt.%, corresponding, on the basis of a total of 7 atoms per formula unit, to Ag2.24Cu0.82As0.94Sb0.01S2.99. The new mineral has been approved by the International Mineralogical Association Commission on New Minerals, Nomenclature and Classification (2014-063) and named for Markus Ecker, a well known mineral expert on the Lengenbach minerals for more than 25 years. [ABSTRACT FROM AUTHOR]

A single crystal of natrojarosite, NaFe3(SO4)2(OH)6, was investigated by single-crystal X-ray diffraction at high-pressure conditions (up to 8.8 GPa) using a diamond-anvil cell. The unit-cell parameters were determined at 11 different pressures and no indications of a phase transition were found up to the maximum pressure reached. The volume and axial moduli were fitted to a third-order Birch-Murnaghan equation-of-state which gave the following values: V0 = 769.6(2) Å3, KT0 = 50.6(9) GPa, K' = 9.9(4); a = 7.3172(6) Å, KT' = 104(2), K' = 7.6(9); c = 16.5965(20) Å, KT0 = 24.6(4) and K' = 7.1(2). The crystal structure of natrojarosite was refined at seven different pressures up to 8.779(11) GPa [a = 7.3170(4), c = 16.5955(5) Å and V = 769.46(9) Å 3 in R3m at 0.00010(1) GPa and a = 7.1594(8), c = 15.6003(17) Å and V = 692.49(8) Å 3 at 8.779(11) GPa]. The structural analysis shows that the 12-fold Na polyhedron accommodates most of the deformation by a large volume decrease (14%) and strong polyhedral distortion (63%). Our results indicate that natrojarosite has the most compressible structure of the supergroup studied sofar, and has a very strong axial anisotropy. [ABSTRACT FROM AUTHOR]

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)(2̅01); 3.791(26)(2̅11); 3.338(21)(310); 3.291(100)(220, 021), 3.256(67)(211,1̅21), 2.968(22)(2̅21), 2.647(24)(4̅01); for cobaltoblödite: 4.551(80)(210, 011); 4.269(50)(2̅01); 3.795(18)(2̅11); 3.339(43)(310); 3.29(100)(220, 021), 3.258(58)(211, 1̅21), 2.644(21)( 4̅01), 2.296(22)( 1̅22). The crystal structures of both minerals were refined by single-crystal X-ray diffraction to R1 = 0.0459 (manganoblödite) and R1 = 0.0339 (cobaltoblödite). [ABSTRACT FROM AUTHOR]

A scarab found in grave 25 of the Monte Prama necropolis, near Cabras, Oristano, Sardinia, is of special importance for the archaeological interpretation and dating of this important archaeological site. The object has been misinterpreted in the past as composed by bone: recent archaeometric analyses showed that it is a glazed steatite of Egyptian origin and that the altered surface contains interesting phases crystallized during the high-temperature interaction of the Mg-rich talc core with the alkali-rich glass used for glazing. A novel single crystal X-ray diffraction analysis of one of the phases indicates that it is a new compound having the milarite-osumilite structure type, with a peculiar composition close to (NaK□)(Mg)(MgCuFe)(SiAl)O, not reported for naturally occurring minerals. The structural and crystal chemical features of the compound, together with the known high-temperature stability of the series, allow a complete interpretation of the glazing process and conditions, based on direct application of the glaze on the steatite core with subsequent treatment at temperatures above 1000 °C. [ABSTRACT FROM AUTHOR]

Abstract: A natural crystal with NaMnSi2O6 composition (space group C2/c) belonging to the family of clinopyroxene structures was investigated by in-situ high-pressure single-crystal X-ray diffraction up to 9 GPa in order to verify if the compressibility can be predicted from the unit-cell volume V 0 at 1 bar applying an established volume–compressibility relationship. Together with data for isostructural analogue phases the equation-of-state parameters of NaMnSi2O6 showed that such simplified relationship can not be longer applied. The findings demonstrate that prediction models for isostructural series are consistent not only for the aspect of structural isotopy, and valid relationships presuppose similar character of the electronic structure. In case of pyroxenes containing transition elements the established relationship is only valid for series of compounds with cations of identical oxidation state according to isovalent electronic character. [Copyright &y& Elsevier]

Abstract: The equation of state of a single-crystal synthetic silicate NaInSi2O6 was determined from the unit cell parameters measured by X-ray diffraction using a diamond-anvil cell at 12 different pressures up to 7.83(1) GPa in order to provide a definitive model capable of predicting the high-pressure behavior of NaMe3 +Si2O6 silicate compounds. The data were fitted by a third-order Birch–Murnaghan equation of state obtaining the following coefficients: , . Our results show similar results for NaMe3 +Si2O6 compounds and confirm that for this mineral family, the empirical relationship proposed in previous investigations is valid for isostructural compounds only if they share the same valence electron character. In addition, we collected intensity data on the same compound at 16 different pressures up to 9.467 GPa using a diamond-anvil cell with diamond backing plates. The main structural compression mechanism is played by the tetrahedral chain kinking, which is related to the shortening of Na–O3long distances. Comparing our equation of state and high-pressure crystal structural results with previous data on NaMe3 +Si2O6 pyroxenes, we show that their compressibility increases much faster with the size of Me3 + cation when this one is a 3d transition metal. [Copyright &y& Elsevier]

Four synthetic crystals belonging to the jadeite (Jd, NaAlSi2O6)-hedenbergite (Hd, CaFeSi2O6) solid solution were investigated by X-ray diffraction in situ at high pressure using a diamond anvil cell to Pmax = 10.6 GPa. The samples exhibited space group symmetry C2/c throughout the investigated pressure range and did not show any phase transformations. V0, KT0, and K′ were simultaneously refined by fitting a third-order Birch-Murnaghan equation of state to pressure-volume data for all samples. The following relationship between bulk modulus and molar fraction of jadeite is observed: KT0 = 108.7(2) (GPa) + 0.191(9) × [% molar Jd] + 0.0006(1) × [% molar Jd]2 The bulk modulus of hedenbergite is 19% lower than jadeite with a strong axial anisotropy that increases with increasing the Hd content. In particular, the compressibility along the b axis (the most compressible in pyroxenes) increases by about 35% going from Jd to Hd while along the c axis the increase in compressibility is about 24%. The a axis does not show any variation in the deformation rate along the join. The analysis of the crystal structure behavior with pressure for all samples clearly indicates that the main cause of the strong anisotropy on the b-c plane is related to the narrowing of the M1 octahedral chain and to anion-anion interactions increasing the packing efficiency of the anion skeletons of the crystals going from Jd to Hd. [ABSTRACT FROM AUTHOR]

Synthetic NaGaSi2O6-pyroxene, space group C2/c, was investigated at low temperature between 295 to 110 K by X-ray diffraction. The evolution of the unit-cell parameters as a function of temperature does not indicate any structural phase transition down to 110 K. Calculated values for the Debye temperature, θD, and the Grüneisen parameter, γ, are 653(39) and 0.84(8) K, respectively, close to those of other pyroxenes. Five complete intensity data collections were performed at 295, 235, 190, 145, and 110 K to investigate the temperature dependence of the crystal structure. The space group remains C2/c down to 110 K, but anomalies were found between 235 and 190 K for the temperature dependencies of the volume and strain of the M1 polyhedron. This anomalous behavior could be related to variations of the Ga-O2(C1,D1) bond length and the O1(A1,B1)-Ga-O2(C1,D1) bond angle. The C2/c-P1̅ phase transition observed in a previous work for NaTiSi2O6 at about 200 K did not occur for NaGaSi2O6 down to the minimum temperature investigated in this work. This is not due to the different ionic radius at M1 site or to a different tetrahedral chain extension between these two compositions but it is likely due to unfilled t2g orbitals, which do not exist in NaGaSi2O6. [ABSTRACT FROM AUTHOR]

Synthetic NaGaSi2O6-pyroxene, space group C2/c, was investigated at low temperature between 295 to 110 K by X-ray diffraction. The evolution of the unit-cell parameters as a function of temperature does not indicate any structural phase transition down to 110 K. Calculated values for the Debye temperature, θD, and the Grüneisen parameter, γ, are 653(39) and 0.84(8) K, respectively, close to those of other pyroxenes. Five complete intensity data collections were performed at 295, 235, 190, 145, and 110 K to investigate the temperature dependence of the crystal structure. The space group remains C2/c down to 110 K, but anomalies were found between 235 and 190 K for the temperature dependencies of the volume and strain of the M1 polyhedron. This anomalous behavior could be related to variations of the Ga-O2(C1,D1) bond length and the O1(A1,B1)-Ga-O2(C1,D1) bond angle. The C2/c-P1̅ phase transition observed in a previous work for NaTiSi2O6 at about 200 K did not occur for NaGaSi2O6 down to the minimum temperature investigated in this work. This is not due to the different ionic radius at M1 site or to a different tetrahedral chain extension between these two compositions but it is likely due to unfilled t2g orbitals, which do not exist in NaGaSi2O6. [ABSTRACT FROM AUTHOR]

Garnet is the archetypal cubic mineral, occurring in a wide variety of rock types in Earth's crust and upper mantle. Owing to its prevalence, durability and compositional diversity, garnet is used to investigate a broad range of geological processes. Although birefringence is a characteristic feature of rare Ca–Fe3+ garnet and Ca-rich hydrous garnet, the optical anisotropy that has occasionally been documented in common (that is, anhydrous Ca–Fe2+–Mg–Mn) garnet is generally attributed to internal strain of the cubic structure. Here we show that common garnet with a non-cubic (tetragonal) crystal structure is much more widespread than previously thought, occurring in low-temperature, high-pressure metamorphosed basalts (blueschists) from subduction zones and in low-grade metamorphosed mudstones (phyllites and schists) from orogenic belts. Indeed, a non-cubic symmetry appears to be typical of common garnet that forms at low temperatures (<450 °C), where it has a characteristic Fe–Ca-rich composition with very low Mg contents. We propose that, in most cases, garnet does not initially grow cubic. Our discovery indicates that the crystal chemistry and thermodynamic properties of garnet at low-temperature need to be re-assessed, with potential consequences for the application of garnet as an investigative tool in a broad range of geological environments. [ABSTRACT FROM AUTHOR]

The crystal structure of vanthoffite {hexa­sodium magnesium tetra­kis[sulfate­(VI)]}, Na6Mg(SO4)4, was solved in the year 1964 on a synthetic sample [Fischer & Hellner (1964). Acta Cryst. 17, 1613]. Here we report a redetermination of its crystal structure on a mineral sample with improved precision. It was refined in the space group P21/c from a crystal originating from Surtsey, Iceland. The unique Mg (site symmetry 1̅) and the two S atoms are in usual, only slightly distorted octa­hedral and tetra­hedral coordinations, respectively. The three independent Na atoms are in a distorted octa­hedral coordination (1×) and distorted 7-coordinations inter­mediate between a `split octa­hedron' and a penta­gonal bipyramid (2×). [MgO6] coordination polyhedra inter­change with one half of the sulfate tetra­hedra in <011> chains forming a (100) meshed layer, with dimers formed by edge-sharing [NaO7] polyhedra filling the inter­chain spaces. The other [NaO7] polyhedra are organized in a parallel layer formed by [010] and [001] chains united through edge sharing and bonds to the remaining half of sulfate groups and to [NaO6] octa­hedra. The two types of layers inter­connect through tight bonding, which explains the lack of morphological characteristics typical of layered structures. [ABSTRACT FROM AUTHOR]

A single crystal of a natural orthopyroxene with composition M2[Fe0.8182+Mg0.156Ca0.010Mn0.016]M1[Fe0.0812+ Mg0.767Al0.084Fe0.0683+]TA[Si]TB[Si0.848Al0.152]O6 and space group Pbca (sample S95) was investigated at high pressure by X-ray diffraction using a diamond-anvil cell up to 9.56 GPa. No phase transitions were detected in the pressure range investigated. The unit-cell parameters, a, b, and c, decrease non-linearly with pressure and show an axial compression anisotropy with a ratio βa:βb:βc = 1.00:1.64:1.16. The unit-cell volume decreases non-linearly as well and with a negative variation, by about 6.3% up to 9.56 GPa. The equation of state calculated using high-accuracy volume-pressure data up to 5.5 GPa gave the following coefficients: V0 = 846.02(4) ų, KT0 = 115.4(6) GPa, K' = 7.7(3). Among the Mg-orthopyroxenes investigated at high pressure so far S95 shows the highest bulk modulus. Six complete intensity data were collected at 0, 0.16, 1.72, 3.95, 8.03, and 9.56 GPa. The results confirm previous conclusions regarding the compressional mechanism in orthopyroxenes. At lower pressures, compression is mostly connected to a decrease in volume of the two M-coordination octahedra, accompanied by an increased kink in the B-tetrahedral chain. At higher pressures, compression of the M sites decreases, the kink of the tetrahedral chains stops to change, and reduction in unit-cell volume is accompanied mainly by compression of tetrahedra. This change in compressional trends results in a relatively large K' parameter and a pronounced stiffening of the structure with pressure. The presence of Al in the TB tetrahedral site influences the kink of the B tetrahedral chain, which depends on the ratio of sizes of the M2 and TB coordination polyhedra. The increased stiffness of the M polyhedra, caused by the presence of Fe, is the main reason for the high bulk modulus of S95 and its resistance to shortening of the c axis. This explains the limited shortening of the c axis in S95 and the different compressional axial anisotropy with respect to other orthopyroxenes investigated under high pressure. [ABSTRACT FROM AUTHOR]

The crystal structure of alkali/water-poor beryl (H2O + Na2O + Cs2O < 1.2 wt%) was reinvestigated by means of laser ablation inductively coupled plasma mass spectroscopy, thermogravimetric analysis, neutron diffraction, and polarized infrared spectroscopy to determine the real topological configuration of the extra-framework content in the six-membered ring channels. Analysis of the nuclear density Fourier map suggests that the (water) oxygen is located along the sixfold axis at the 2a site (0,0,1/4), whereas the (water) protons are at -0.028(7), -0.071(3), 0.332(1). The hydrogen atoms are distributed in 6 x 2 equivalent positions, above and below the oxygen site. Geometrical configuration of the water molecule is well defined: the O-H bond distance is 0.949(18) Å and the H-O-H bond angle is 106.9(2.2)º. The H⋯H vector is oriented at ∼4° from [001]. This configuration is completely different from that found in alkali-rich beryl, where the H⋯H vector is perpendicular to [001]. Na is probably located, with the H2O oxygen, at the 2a site. According to the chemical analysis, which shows that the amounts of other alkali and earth-alkali cations are negligible (Rb, K, Mg, Mn ≤ 110 ppm, Ca ≤ 225 ppm, Cs ≤ 430 ppm), no effect of other cations on the extra-framework population was observed in the structural refinement. The final agreement index (R1) of the structural refinement was 0.037 for 34 refined parameters and 160 unique reflections with Fo 4σ(Fo). The topological configuration of the H2O molecule into the channel is confirmed by the spectroscopic investigation. Polarized single-crystal IR spectra show that the H2O molecule is oriented with the molecular symmetry axis perpendicular to the hexagonal axis and H⋯H vector parallel (or quasi-parallel) to [001]. [ABSTRACT FROM AUTHOR]

The new mineral species oxycalcioroméite, Ca2Sb5+2 O6O, has been discovered at the Buca della Vena mine, Stazzema, Apuan Alps, Tuscany, Italy. It occurs as euhedral octahedra, up to 0.1 mm in size, embedded in dolostone lenses in the baryte + pyrite + iron oxides ore. Associated minerals are calcite, cinnabar, derbylite, dolomite, hematite, 'mica', pyrite, sphalerite and 'tourmaline'. Oxycalcioroméite is reddish-brown in colour and transparent. It is isotropic, with ncalc = 1.950. Electron microprobe analysis gave (wt.%; n = 6) Sb2O5 63.73, TiO2 3.53, SnO2 0.28, Sb2O3 10.93, V2O3 0.68, Al2O3 0.28, PbO 0.68, FeO 5.52, MnO 0.13, CaO 13.68, Na2O 0.83, F 1.20, O = F - 0.51, total 100.96. No H2O, above the detection limit, was indicated by either infrared or micro-Raman spectroscopies. The empirical formula, based on 2 cations at the B site, is (Ca1.073Fe2+0.338Sb3+0.330Na0.118 Pb0.013Mn0.008)Σ=1.880(Sb5+ 1.734Ti0.194V0.040Al0.024Sn0.008)Σ=2.000(O6.682F0.278)Σ6.960. The crystal structure study gives a cubic unit cell, space group Fd3m, with a 10.3042(7) Å, V 1094.06(13) Å 3, Z = 8. The five strongest X-ray powder diffraction lines are [d (Å)I (visually estimated)(hkl)]: 3.105(m)(311); 2.977(s)(222); 2.576(m)(400); 1.824(ms)(440); and 1.556(ms)(622). The crystal structure of oxycalcioroméite has been solved by X-ray single-crystal study on the basis of 114 observed reflections, with a final R1 = 0.0114. It agrees with the general features of the members of the pyrochlore supergroup. [ABSTRACT FROM AUTHOR]

The newmineral species canosioite, ideally Ba2Fe3+(AsO4)2(OH), has been discovered in the dump of Valletta mine, Maira Valley, Cuneo Province, Piedmont, Italy. Its origin is probably related to the reaction between ore minerals and hydrothermal fluids. It occurs in reddish-brown granules, subhedralmillimetre-size crystals,with a pale yellow streak and vitreous lustre. Canosioite is associated with aegirine, baryte, calcite, hematite, bronze Mn-bearing muscovite, unidentified Mn oxides and unidentified arsenates. Canosioite is biaxial (+) with a 2Vmeas = 84(2)°. It is weakly pleochroic with X = brownish yellow, Y = brown, Z = reddish brown, Z > Y > X. Canosioite is monoclinic, P21/m, with a = 7.8642(4), b = 6.1083(3), c = 9.1670(5) Å, β = 112.874(6)°, V = 405.73(4) Å3 and Z = 2. Calculated density is 4.943 g cm-3. The seven strongest diffraction lines of the observed powder X-ray diffraction pattern are [d in Å, (I) (hkl)]: 3.713 (18)(111̄), 3.304 (100)(211̄), 3.058 (31)(020), 3.047 (59)(103̄), 2.801 (73)(112), 2.337 (24)(220), 2.158 (24)(123̄). Electron microprobe analyses gave (wt.%): Na2O 0.06, MgO 0.43, CaO 0.02, NiO 0.02, CuO 0.03, SrO 0.42, BaO 49.36, PbO 1.69, Al2O3 1.25,Mn2O3 3.89, Fe2O3 6.95, Sb2O3 0.01, SiO2 0.03, P2O5 0.02,V2O5 10.88, As2O5 24.64, SO3 0.01, F 0.02, H2O 1.61 was calculated on the basis of 1 (OH,F,H2O) group per formula unit. Infrared spectroscopy confirmed the presence of OH. The empirical formula calculated on the basis of 9 O apfu, is (Ba1.92Pb0.05Sr0.02Na0.01)∑2.00(Fe3+0.52Mn3+0.29Al0.15Mg0.06)Σ1.02[(As0.64V0.36)Σ1.00O4]2[(OH0.92F0.01)(H2O)0.07] and the ideal formula is Ba2Fe3+(AsO4)2(OH). The crystal structure was solved by direct methods and found to be isostructural to that of arsenbrackebuschite. The structure model was refined (R1 = 2.6%) on the basis of 1245 observed reflections. Canosioite is named after the small municipality of Canosio, where the type locality, the Valletta mine, is situated. The new mineral and name were approved by the International Mineralogical Association Commission on New Minerals and Mineral Names (IMA2015-030). [ABSTRACT FROM AUTHOR]