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A Microsoft® Visual Basic software, WinClbclas , has been developed to calculate the chemical formulae of columbite-supergroup minerals based on data obtained from wet-chemical and electron-microprobe analyses and using the current nomenclature scheme adopted by the Commission on New Minerals, Nomenclature and Classification (CNMNC) of the International Mineralogical Association (IMA) for columbite-supergroup minerals. The program evaluates 36 IMA-approved species, three questionable in terms of their unit-cell parameters, four insufficiently studied questionable species and one ungrouped species, all according to the dominant valance and constituent status in five mineral groups including ixiolite (M O2), wolframite (M 1 M 2O4), samarskite (AB M2O8), columbite (M 1 M 2O6) and wodginite (M 1 M 2 M 32O8). Mineral compositions of the columbite supergroup are calculated on the basis of 24 oxygen atoms per formula unit. However, the formulae of the five ixiolite to wodginite groups can be estimated by the program on the basis of their cation and anion values in their typical mineral formulae (e.g. 4 cations and 8 oxygens for the wodginite group) with normalisation procedures. The Fe3+ and Fe2+ contents from microprobe-derived total FeO (wt.%) amounts are estimated by stoichiometric constraints. WinClbclas allows users to: (1) enter up to 47 input variables for mineral compositions; (2) type and load multiple columbite-supergroup mineral compositions in the data entry section; (3) edit and load the Microsoft® Excel files used in calculating, classifying, and naming the columbite-supergroup minerals, together with the total monovalent to hexavalent ion; and (4) store all the calculated parameters in the output of a Microsoft® Excel file for further data evaluation. The program is distributed as a self-extracting setup file, including the necessary support files used by the program, a help file and representative sample data files. [ABSTRACT FROM AUTHOR]

Intracrystalline distribution of ferrous and ferric iron within pumpellyites (VII W 8VI X 4VI Y 8IV Z 12O56– n (OH) n , Z = 1) from low-grade metamorphic green rocks of the Kanogawa unit in the Northern Chichibu Belt, Hijikawa district, western Shikoku, Japan, was investigated using electron microprobe analysis, X-ray Rietveld refinement, and 57Fe Mössbauer spectroscopic analysis to verify the regularity of the distribution of Fe within the octahedral X and Y sites in pumpellyite and its effect on the pumpellyite structure. Two Fe-rich pumpellyite samples, labelled CLW and CHG, with average total Fe2O3 of 10.01±1.69 and 16.07±1.08 wt.%, respectively, were separated from the rock samples. The site occupancies at the X and Y sites in the CLW and CHG pumpellyites, refined using powder X-ray diffraction data, are X [Mg0.298Fe0.298(5)Al0.405] Y [Fe0.191Al0.809] and X [Mg0.244Fe0.42(1)Al0.34] Y [Fe0.32Al0.68], respectively. The Fe2+:Fe3+ ratio of the CLW pumpellyite, determined using Mössbauer spectroscopy, is 12(1):88(3). By combining the average chemical composition data, the site occupancies at the X and Y sites, and the Fe2+:Fe3+ ratio of the CLW pumpellyite, the chemical formulae of CLW and CHG pumpellyites are constructed as (Ca7.96K0.02Na0.01)Σ7.99(Mg1.19Mn2+0.09Fe2+0.39Fe3+0.71Al1.62)Σ4.00(Al6.47Fe3+1.50V0.02Ti0.01)Σ8.00Si12.26O43.33(OH)12.67 and (Ca8.01K0.01)Σ8.02(Mg0.97Mn2+0.02Fe2+0.63Fe3+1.03Al1.19)Σ4.01(Al5.44Fe3+2.55V0.01)Σ8.00Si12.02O42.69OH)13.31, respectively, implying that the proper name of both pumpellyites is pumpellyite-(Al). The intracrystalline distribution coefficients of Fe3+ versus Al between the X and Y sites, K D = (Fe3+/Al) X /(Fe3+/Al) Y , are 1.62 and 1.90 for the CLW and CHG pumpellyites, respectively, implying stronger X -site preference of Fe3+ than Al3+. In the CHG pumpellyite, where the Fe contents at the X and Y sites are higher than in the CLW pumpellyite, the mean < X –O> and < Y –O> distances are 2.06 and 1.98 Å, respectively, which are larger than < X –O> = 2.040 and < Y –O> = 1.944 Å in the CLW pumpellyite. The unit-cell parameters of the CHG pumpellyite are a = 8.8672(3), b = 5.9562(2), c = 19.1899(6) Å, β = 97.473(2)° with V = 1004.9(2) Å3 and are larger than those of the CLW pumpellyite, a = 8.8456(4), b = 5.9393(2), c = 19.1613(8) Å, β = 97.461(3)° with V = 998.14(7) Å3. [ABSTRACT FROM AUTHOR]

An investigation of sample 41647 from the Platinum Placer of Ugol'nyi Ruchei, Norilsk Cu–Ni deposit, Russia, stored in the systematic collection of the Fersman Mineralogical Museum, revealed that it contained a mineral that can be identified as the original stannopalladinite described in 1947. As the literature information on the latter is controversial, the mineral was re-investigated using modern analytical techniques. Stannopalladinite occurs as spherical and ovoid-shaped grains up to 0.08 mm, closely intergrown with tetraferroplatinum as part of flattened, prismatic crystals up to 6 mm long. The micro-indentation hardness of stannopalladinite (VHN, 30 g load) is 244 kg/mm2 (range 233–266, n = 4), corresponding to a Mohs hardness of 4. The calculated density is 9.781 g/cm3. In reflected light, stannopalladinite is pale pink. The bireflectance is noticeable only in oil immersion. In crossed nicols the mineral exhibits strong anisotropy with colour effects changing from reddish purple to greyish blue and polysynthetic twinning of grains. The reflectance curves show distinct anomalous dispersion. The chemical composition (wt.%, electron microprobe data, mean of 11 analyses) is: Cu 8.48, Pd 61.21, Pt 0.89, Sn 25.87, Pb 3.70, total 100.15. The empirical formula calculated on the basis of 4 atoms per formula unit is (Pd2.42Cu0.56Pt0.02)Σ3.00(Sn0.92Pb0.08)Σ1.00. The ideal chemical formula of stannopalladinite is therefore proposed as (Pd,Cu)3Sn instead of Pd3Sn2 used in the official IMA List of Minerals. The strongest powder X-ray diffraction lines are [ d obs, Å (I , %) (hkl) ]: 2.292 (42) (231), 2.166 (100) (331), 2.034 (10) (710), 1.916 (15) (141) and 1.851 (15) (630). The powder X-ray data are indexed in the orthorhombic unit cell with a = 14.634(2), b = 8.5253(6), c = 4.5946(3) Å and V = 573.24(7) Å3 (Z = 8). Stannopalladinite can be reliably identified among all other minerals belonging to the binary Pd–Sn and ternary Pd–Cu–Sn systems by a combination of chemical, optical and X-ray data. [ABSTRACT FROM AUTHOR]

A new occurrence of austinite, CaZnAsO4(OH), conichalcite, CaCuAsO4(OH), and zincolivenite, CuZnAsO4(OH), is described from the Tripi mine, Peloritani Mountains, Sicily, Italy. These species have been observed in euhedral crystals in vugs of a calcite vein and were characterised using single-crystal X-ray diffraction, electron microprobe analysis and micro-Raman spectroscopy. Austinite and conichalcite have isotypic relations, both crystallising in space group P 212121. Unit-cell parameters of austinite are a = 7.4931(5), b = 9.0256(6), c = 5.9155(4) Å, V = 400.06(5) Å3; its crystal structure was refined on the basis of 1210 unique reflections with F o > 4σ(F o) and 77 least-square parameters to R 1 = 0.0236. Conichalcite has unit-cell parameters a = 7.419(10), b = 9.111(11), c = 5.867(7) Å and V = 396.6(1.4) Å3; the diffraction quality of its available grains was not good enough to allow a high-quality structural refinement. Chemical formulae of austinite and conichalcite are Ca1.04(1)Zn0.86(4)Cu0.09(4)As0.98(2)P0.02(1)O4(OH)0.98 and Ca0.98(1)Fe2+0.02(4)Cu0.69(10)Zn0.30(6)As0.97(2)P0.03(1)O4(OH)0.98, respectively. The new chemical data on the austinite–conichalcite isotypic pair, coupled with previous analyses, supports a possible miscibility gap between the compositions (Zn0.25Cu0.75) and (Zn0.50Cu0.50). Zincolivenite has unit-cell parameters a = 8.4594(9), b = 8.5324(8), c = 5.9893(6) Å, V = 432.30(12) Å3 and space group Pnnm ; its crystal structure was refined to R 1 = 0.0230 for 523 unique reflections with F o > 4σ(F o) and 47 least-square parameters. Its chemical composition is Cu0.73(5)Zn1.25(5)As1.01(1)O4(OH)1.01. The refinement of the crystal structure supports the ordering of Cu and Zn in two different crystallographic sites. Micro-Raman spectra of austinite, conichalcite and zincolivenite are discussed, with a focus on the O–H stretching region where local Zn and Cu arrangements affect the position of Raman bands in zincolivenite. These arsenates probably play an environmental role in the Peloritani area, where the occurrence of high contents of some potentially toxic elements in soils and stream sediments has been reported. [ABSTRACT FROM AUTHOR]

Aluminotaipingite-(CeCa), (Ce6Ca3)Al(SiO4)3[SiO3(OH)]4F3 , is a new member of the cerite-supergroup minerals, whose general chemical formula is A 9 XM [ T O3Ø]7 Z 3, (A = REE, Ca, Sr, Na and □; X = □, Ca, Na and Fe2+; M = Mg, Fe2+, Fe3+, Al and Mn; T = Si and P; Ø = O and OH; Z = □, OH and F). It was found in cavities of a leucogranitic orthogneiss at the Casette quarry, Montoso, Bagnolo Piemonte, Cuneo Province, Piedmont, Italy. Crystals of aluminotaipingite-(CeCa) are light pink to pink, transparent or semi-transparent, with a vitreous lustre. It forms pyramidal crystals up to 0.07 mm in size and observed forms are {0 0 1}, {1 0 $\bar{2}$ }. The tenacity is brittle, no distinct cleavage is observed and the fracture is uneven. The mineral does not fluoresce in long- or short-wave ultraviolet light. The streak is white. Hardness (Mohs) = 5. The calculated density is 4.476 g cm–3. The mineral is trigonal, space group R 3 c , with a = 10.658(3), c = 37.865(9) Å, V = 3725(2) Å3 and Z = 6. The eight strongest powder X-ray diffraction lines are [ d obs, Å (I, %) (h k l)]: 8.38(29)(0 1 2), 4.499(28)(2 0 2), 3.282(41)(2 1 4), 2.936(100)(0 2 10), 2.816(51)(1 2 8), 2.669(37)(2 2 0), 2.207 (29)(3 0 12) and 1.935(35)(2 3 8). The structure was refined to R =0.0306 for 2297 reflections with I >2σ(I). The crystal structure of aluminotaipingite-(CeCa) contains two nine-fold coordinated sites (A 1 and A 2), which are occupied mainly by lanthanides, and a third nine-fold coordinated A 3 site containing almost equal amounts of lanthanides and Ca. The X site is vacant and at the octahedral M site aluminium prevails over Fe3+. Among the three independent T sites, T 2 belongs to a (SiO4)4– anion, whereas T 1 and T 3 belong to (SiO3OH)3– anions. Fluorine is involved in coordination with the A 1 and A 3 sites. [ABSTRACT FROM AUTHOR]

The thermal behaviour of fedorite from the Murun massif, Russia, has been investigated by means of electron probe microanalysis (EPMA), differential thermal analysis (DTA), thermogravimetry (TG), in situ high-temperature single-crystal X-ray diffraction (HT-SCXRD), ex situ high-temperature Fourier-transform infrared spectroscopy (HT-FTIR). The empirical chemical formula of the sample of fedorite studied is: (Na1.56K0.72Sr0.12)Σ2.40(Ca4.42Na2.54Mn0.02Fe0.01Mg0.01)Σ7.00(Si15.98Al0.02)Σ16.00(F1.92Cl0.09)Σ2.01(O37.93OH0.07)Σ38.00⋅2.8H2O. The TG curve provides a total mass decrease of ~5.5%, associated with dehydration and defluorination processes from 25 to 1050°C. Fedorite crystallises in space group P $\bar{1}$ and has: a = 9.6458(2), b = 9.6521(2), c = 12.6202(4) Å, α = 102.458(2), β = 96.2250(10), γ = 119.9020(10)° and cell volume, V = 961.69(5) Å3. The HT-SCXRD was carried out in air in the 25–600°C range. Overall, a continuous expansion of the unit-cell volume was observed although the c cell dimension slightly decreases in the explored temperature range. Structure refinements indicated that the mineral undergoes a dehydration process with the loss of most of the interlayer H2O from 25 to 300°C. The HT-FTIR spectra confirmed that fedorite progressively dehydrates until 700°C. [ABSTRACT FROM AUTHOR]

The criteria for the definition of a new mineral species currently used by the Commission on New Minerals Nomenclature and Classification (CNMNC) of the International Mineralogical Association are critically examined. In particular, the rule of the dominant constituent can violate the laws of conservation of electric charge. A series of additional rules: (1) valency-imposed double site-occupancy; (2) the dominant-valency rule; and (3) the site-total-charge approach, have been developed in an attempt to correct this error. However, none of these rules can overcome the fundamental flaw introduced by the rule of the dominant constituent, and the chemical formulae resulting from application of these rules can violate the requirements of an end-member, particularly that of electroneutrality. As a result, the IMA–CNMNC rules cannot derive end-member formulae for some groups of minerals, giving rise to many ad hoc decisions in defining distinct mineral species. [ABSTRACT FROM AUTHOR]

Argentotetrahedrite-(Cd), Ag6(Cu4Cd2)Sb4S13, has been approved as a new mineral species by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association using samples from Rudno nad Hronom, Slovak Republic. It occurs as anhedral grains up to 30 μm in size, steel-grey to black in colour, with a metallic lustre, in association with greenockite and other tetrahedrite-group minerals [argentotetrahedrite-(Zn) and tetrahedrite-(Zn)], earlier base-metal minerals, Ag sulfides and sulfosalts (acanthite, pyrargyrite and polybasite) and later galena. Argentotetrahedrite-(Cd) is isotropic, grey in colour, with a creamy tint and rapidly (tens of minutes) tarnishes to orange–brown. Reflectance data for Commission on Ore Mineralogy (COM) wavelengths in air are [λ (nm), R (%)]: 470, 30.4; 546, 30.3; 589, 30.3; and 650, 28.7. The chemical formula of the samples studied, recalculated on the basis of Σ Me = 16 atoms per formula unit, is: (Ag3.28Cu2.72)Ʃ6.00[Cu4(Cd1.68Fe0.27Zn0.16)]Ʃ6.11(Sb3.71As0.15)Ʃ3.86S12.79. Argentotetrahedrite-(Cd) is cubic, I $\bar{4}$ 3 m , with a = 10.65(2) Å, V = 1208(4) Å3 and Z = 2. Argentotetrahedrite-(Cd) is isotypic with other members of the tetrahedrite group. The structural relationship between argentotetrahedrite-(Cd) and other members of the freibergite series are discussed and previous findings of this species are briefly reviewed. [ABSTRACT FROM AUTHOR]

Grandviewite is redefined on the basis of a reinvestigation of the holotype specimen from the Grandview mine, Arizona, USA, and additional specimens found in the Restauradora vein at the Capillitas mine, northwestern Argentina. Grandviewite from the Capillitas mine forms globular masses up to a couple of millimetres in diameter, formed by very thin platy to acicular lath-like crystals, greenish-pale blue in colour, pleochroic (X = colourless, Y = very pale blue and Z = greenish-pale blue), with pale blue streak and silky to a satiny lustre. Results of an electron-microprobe study and crystal-structure determination lead to the new ideal formula Cu3Al2(SO4)(OH)10⋅H2O, which requires (in wt.%) CuO 45.13, Al2O3 19.28, SO3 15.14, and H2O 20.45, total 100.00. Its empirical formulas are (Cu2.96Mn0.01)Σ2.97Al2.03(SO4)0.97(SiO4)0.03(AsO4)0.01(OH)9.97Cl0.01⋅H2O (Grandview mine) and Cu2.97(Al2.03Fe0.01)Σ2.04(SO4)0.95(SiO4)0.03(AsO4)0.01(PO4)0.01(OH)9.97Cl0.01⋅H2O (Capillitas mine). Grandviewite is triclinic, P $\bar{1}$ , with unit-cell parameters refined from powder X-ray diffraction data: a = 5.713(2), b = 10.1374(8), c = 10.9791(9) Å, α = 72.240(6)°, β = 82.79(2)°, γ = 86.07(2)°, V = 600.5(3) Å3 and Z = 2 (Grandview mine); and a = 5.749(3), b = 10.1388(13), c = 10.9656(16) Å, α = 72.344(1)°, β = 82.83(4)°, γ = 86.77(3)°, V = 604.2(3) Å3 and Z = 2 (Capillitas mine). The crystal structure of grandviewite from the Capillitas mine was solved by 3-dimensional electron diffraction analysis (R(obs)/wR(obs) = 0.1304/0.1316 for 6401/31007 observed reflections with I ≥ 3σ(I). Grandviewite contains infinite AlO6–Cu1–AlO6 slabs along a connected on both ends to Cu2 [4 + 1]–SO4 chains. The SO4 tetrahedra form a disordered chain along a connected to the Cu2 pyramids on one side and are otherwise stabilised by strong hydrogen bonds to surrounding units. The Raman and infrared spectra for samples from both occurrences are identical. The redefinition (new chemical formula and triclinic symmetry) has been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (number 21-K). [ABSTRACT FROM AUTHOR]

Ferrofettelite, ideally [Ag6As2S7][Ag10FeAs2S8], is a new mineral (IMA2021-094) from the Glasberg quarry, Nieder-Beerbach, Odenwald, south-western Germany. It occurs as anhedral to subhedral flakes and grains up to 80 μm, associated with proustite and xanthoconite, on arsenolite, calcite and prehnite. Ferrofettelite is opaque with a metallic lustre and possesses a dark reddish-grey streak. It is brittle with an uneven fracture; the Vickers microhardness (VHN20) is 122 kg/mm2 (range 111–131). The calculated density is 5.74 g/cm3 (on the basis of the empirical formula). In plane-polarised reflected light, ferrofettelite is greyish white. Between crossed polars it is weakly anisotropic with red internal reflections. Electron-microprobe analyses give the chemical formula Ag16.04(Fe0.55Hg0.40Cu0.02)Σ0.97(As3.94Sb0.03)Σ3.97S15.02 on the basis of total atoms = 36. Ferrofettelite is monoclinic, space group C2, with a = 26.011(2), b = 15.048(1), c = 15.513(1) Å, β = 90.40(1)° and V = 6071.9(7) Å3 for Z = 8. The six strongest Bragg peaks in the powder X-ray diffraction pattern (d, Å (I, %) (hkl) are: 3.18 (50) ($\bar{8}$ 01), 3.104 (100) (005), 3.004 (60) ($\bar{8}$ 02), 2.755 (40) ($\bar{4}$ 43), 2.501 (30) ($\bar{4}$ 44) and 1.880 (30) ($\overline {12}$ 40). The crystal structure can be described as the alternation of two kinds of layers along the c-axis: layer A with general composition [Ag6As2S7]2– and layer B with a general composition of [Ag10FeAs2S8]2+. In the structure, the Ag atoms adopt various coordinations extending from quasi linear to quasi tetrahedral, the AsS3 groups form pyramids as are typically observed in sulfosalts, and mixed (Fe,Hg) links two sulfur atoms in a linear coordination. Ferrofettelite is the first reported inorganic phase showing a linear coordination for Fe2+. The high-temperature behaviour of ferrofettelite was studied up to 410 K and compared to that of fettelite. [ABSTRACT FROM AUTHOR]

Argentotetrahedrite-(Zn), Ag6(Cu4Zn2)Sb4S13, has been approved as a new mineral species by the International Mineralogical Association Commission on New Minerals, Nomenclature and Classification (IMA-CNMNC) using samples from Kremnica, Slovak Republic (hereafter KR), and Lengenbach, Switzerland (LE). Additionally, it was also identified at the small deposit of Zvěstov (Stříbrnice), Czech Republic (ZV). At the Slovak locality, it occurs as anhedral grains up to 0.1 mm in size, steel-grey in colour, with a metallic lustre, in association with 'argentotennantite-(Fe)' and tiny chalcopyrite grains in quartz gangue. At Lengenbach, it was found as domains of tristetrahedral crystal of tetrahedrite-(Zn), up to 1 mm in size, associated with dolomite. At Zvěstov, it occurs as irregular aggregates, up to 0.2 mm in size, partly rimmed by kenoargentotetrahedrite-(Fe). Argentotetrahedrite-(Zn) is isotropic, grey in colour, with blue-greenish tints. Reflectance data for COM wavelengths in air (KR sample) are [λ (nm), R (%)]: 470, 30.1; 546, 29.8; 589, 29.8; and 650, 28.3. Chemical formulae of the samples studied, recalculated on the basis of ΣMe = 16 apfu (atoms per formula unit), are: (Ag3.27Cu2.69)Σ5.96[Cu4.00(Zn1.69Fe0.23Cu0.05Cd0.02Hg0.01)Σ2.00](Sb3.86As0.17)Σ4.03S12.73 (KR), (Ag3.17Cu2.79)Σ5.96[Cu4.00(Zn1.55Cd0.23Fe0.16Cu0.05Hg0.01)Σ2.00](Sb3.71As0.32)Σ4.03S12.77 (LE) and (Ag3.27Cu2.67)Σ5.94[Cu4.00(Zn1.39Fe0.50Cu0.07Cd0.03Hg0.01)Σ2.00](Sb4.03As0.04)Σ4.07S13.08 (ZV). Argentotetrahedrite-(Zn) is cubic, I $\overline 4$ 3m, with a = 10.5505(10) Å, V = 1174.4(3) Å3 and Z = 2 (KR); a = 10.5155(13) Å and V = 1162.8(4) Å3 (LE); and a = 10.5663(12) Å and V = 1179.7 Å3 (ZV). The crystal structure of argentotetrahedrite-(Zn) has been refined by single-crystal X-ray diffraction data to a final R1 = 0.035 on the basis of 327 unique reflections with Fo > 4σ(Fo) and 22 refined parameters (sample KR). Argentotetrahedrite-(Zn) is isotypic with other members of the tetrahedrite group. The structural relationship between argentotetrahedrite-(Zn) and other members of the freibergite series are discussed and previous findings of this species are briefly reviewed. [ABSTRACT FROM AUTHOR]

Garpenbergite is a new mineral (IMA2020-099) from the Garpenberg Norra mine, Hedemora, Dalarna, Sweden. It occurs with carlfrancisite and minor stibarsen, paradocrasite and filipstadite in a fractured skarn matrix of granular jacobsite, alleghanyite, kutnohorite and dolomite. Crystals are short-prismatic, up to 1.5 mm in length. They have a blackish to greyish brown colour, and are lustrous semi-opaque, with brown streak. Garpenbergite is brittle, with an uneven to subconchoidal fracture. Cleavage is distinct on {010}. Hardness ≈ 5 (Mohs) and VHN100 = 650(40). Dcalc = 4.47(1) g⋅cm−3, overall ncalc = 1.85. Maximum specular reflectance values (%) obtained are 9.2 (470 nm), 9.1 (546 nm), 9.0 (589 nm) and 8.9 (650 nm). The empirical chemical formula of garpenbergite, based on electron microprobe data, is (Mn2+3.97Mg1.48Mn3+0.26Zn0.29)Σ6.00(As0.89Fe3+0.04Mn3+0.06Si0.01)Σ1.00(Sb0.98Fe0.02)Σ1O10[(OH)1.99Cl0.01]Σ2.00. The five strongest Bragg peaks in the powder X-ray diffraction pattern [d, Å (I, %) (hkl)] are 3.05 (30) (002), 2.665 (100) (161), 2.616 (40) (301), 2.586 (25) (251) and 1.545 (45) (462). The orthorhombic unit-cell dimensions (in Å) are a = 8.6790(9), b = 18.9057(19) and c = 6.1066(6), with V = 1001.99(18) Å3 for Z = 4. The crystal structure was refined from single-crystal X-ray diffraction data in the space-group Ibmm to R1 = 3.7% for 957 reflections. Garpenbergite, ideally Mn6As5+Sb5+O10(OH)2, is isostructural with manganostibite, Mn7AsSbO12, but possesses a cation vacancy (□) at an octahedrally coordinated structural site; the two minerals are thus related by the exchange Mn2+ + 2O2– → □ + 2(OH)–. The presence of hydroxyl groups is supported by vibration bands at 3647 and 3622 cm−1 in the Raman spectrum of garpenbergite and by bond-valence considerations. [ABSTRACT FROM AUTHOR]

Thermessaite-(NH4), ideally (NH4)2AlF3(SO4), is a new mineral found as a medium- to high-temperature (~250–300°C) fumarole encrustation at the rim of La Fossa crater, Vulcano, Aeolian Islands, Italy. The mineral deposited as aggregates of minute (<0.2 mm) sharp prismatic crystals on the surface of a pyroclastic breccia in association with thermessaite, sulfur, arcanite, mascagnite, and intermediate members of the arcanite–mascagnite series. The new mineral is colourless to white, transparent, non-fluorescent, has a vitreous lustre, and a white streak. The calculated density is 2.185 g/cm3. Thermessaite-(NH4) is orthorhombic, space group Pbcn, with a = 11.3005(3) Å, b = 8.6125(3) Å, c = 6.8501(2) Å, V = 666.69(4) Å3 and Z = 4. The eight strongest reflections in the powder X-ray diffraction data [d in Å (I)(hkl)] are: 5.65 (100)(200), 4.84 (89)(111), 6.85 (74)(110), 3.06 (56)(112), 3.06 (53)(221), 3.08 (47)(311), 2.68 (28)(022) and 2.78 (26)(130). The average chemical composition, determined by quantitative SEM-EDS (N by difference), is (wt.%): K2O 3.38, Al2O3 25.35, SO3 36.58, F 26.12, (NH4)2O 22.47, O = F –11.00, total 102.90. The empirical chemical formula, calculated on the basis of 7 anions per formula unit, is [(NH4)1.85K0.15]Σ2.00Al1.06F2.94S0.98O3.06. The crystal structure, determined from single-crystal X-ray diffraction data [R(F) = 0.0367], is characterised by corner-sharing AlF4O2 octahedra which form [001] octahedral chains by sharing two trans fluoride atoms [Al–F2 = 1.8394(6) Å]. Non-bridging Al–F1 distances are shorter [1.756(1) Å]. The two trans oxygen atoms [Al–O = 1.920(2) Å] are from SO4 tetrahedra. NH4+ ions occur in layers parallel to (100) which alternate regularly with (100) layers containing ribbons of corner-sharing AlF4O2 octahedra and associated SO4 groups. The NH4+ ions are surrounded by five oxygen atoms and by four fluorine atoms. The mineral is named as the (NH4)-analogue of thermessaite, K2AlF3(SO4), and corresponds to an anthropogenic phase found in the burning Anna I coal dump of the Anna mine, Aachen, Germany. Both mineral and mineral name have been approved by the International Mineralogical Association Commission on New Minerals, Nomenclature and Classification (IMA2011-077). [ABSTRACT FROM AUTHOR]

The occurrence, chemical composition and structural characterisation of the new mineral kernowite, ideally Cu2Fe(AsO4)(OH)4⋅4H2O, the Fe3+-analogue of liroconite, Cu2Al(AsO4)(OH)4⋅4H2O, are described. Kernowite (IMA2020-053) occurs on specimens probably sourced from the Wheal Gorland mine, St Day, Cornwall, UK, in the cavities of a quartz-gossan rich in undifferentiated micro-crystalline grey sulfides and poorly crystalline arsenic phases including both pharmacosiderite and olivenite-group minerals. The average composition of kernowite determined from several holotype fragments by electron microprobe analysis is Cu1.88(Fe0.79Al0.09)Σ0.88(As1.12O4)(OH)4⋅3.65H2O. The structure of kernowite has been determined in monoclinic space group I2/a (a non-standard setting of C2/c) by single-crystal X-ray diffraction (SCXRD) to R1 = 0.025, wR2 = 0.051 and Goodness-of-fit = 1.112. Unit-cell parameters from SCXRD are a = 12.9243(4) Å, b = 7.5401(3) Å, c = 10.0271(3) Å, β = 91.267(3)°, V = 976.91(6) Å3 and Z = 4. The chemical formula of this crystal indicated by SCXRD from refined site-scattering is Cu2(Fe3+0.84(1)Al0.16)AsO4(OH)4⋅4H2O. The network of hydrogen bonding has been determined and is similar to that reported for liroconite from Wheal Gorland by Plumhoff et al. (2020). [ABSTRACT FROM AUTHOR]

Molecular formulae used to recalculate nepheline analyses generally have different numbers of oxygens (e.g. NaAlSiO4 (Ne), KAlSiO4, (Ks), CaAl2Si2O8 (An) and SiO2 (Q)). A 32 oxygen cell has 16 T cations and 8 cavity sites, but ideal nepheline stoichiometry is not necessarily followed. Ca end-member □CaCaAl2Si2O4 (CaNe) and excess silica end-member □SiSi2O4 (Q') calculation requires inclusion of both vacancy species as cavity cation values. Q' parameter calculations can involve different assumptions and four parameters are described: Qxs; QSi; Q(Si-Al); and Qcavity; these should have closely similar values for high-quality, stoichiometric analyses. Representative published compositions are recalculated to assess whether authors followed ideal nepheline stoichiometry. Phenocrysts from peralkaline rocks and nephelinites typically exhibit Al deficiencies reflected in negative Δ(Al - cavity cation) parameters (ΔAlcc), negative 'normative' corundum (Al2O3, Cn), and anomalously low or negative Qxs parameters; for such rock types Q(Si-Al) provides a better estimate of excess silica contents. A ΔT-site (cation charge) parameter (ΔTcharge), is closely coupled to ΔAlcc and end-member NaAlSiO4 has a ΔAlcc/ΔTcharge ratio of 1.4296; the derivation of this value is controlled by strict stuffed-tridymite, unit-cell constraints. Natural nephelines all contain excess silica with a mean ΔAlcc/ΔTcharge of 1~134 reflecting their Si/Al ratio being > 1. Nepheline analyses with relatively low Al and Si and high Na (also Ca) contents are common; this might reflect the presence of small amounts (up to ~5%) of cancrinite as an alteration phase or perhaps even in solid solution. The compositions of alteration lamellae of Ca-rich cancrinite in altered nepheline phenocrysts in phonolites from the Marangudzi alkaline complex, Zimbabwe, are used to define diagnostic parameters for recognising such non-stoichiometry. These alteration lamellae formed hydrothermally from Ca-rich and Kpoor fluids. An EXCEL file is provided to help researchers to standardise calculation of nepheline end-member molecular proportions. [ABSTRACT FROM AUTHOR]

Khademite, ideally Al(SO4)F(H2O)5, from the Monte Arsiccio mine, Apuan Alps, Tuscany, Italy, has been characterised through quantitative electron microprobe analysis, micro-Raman spectroscopy and single-crystal X-ray diffraction. Khademite occurs as colourless to whitish tabular crystals, up to 5 mm. Electron microprobe analysis (in wt.%, average of 20 spot analyses) gave: SO3 35.43, Al2O3 21.27, F 6.92, H2Ocalc 39.73, sum 103.35, –O = F 2.92, total 100.43. On the basis of 10 anions per formula unit, assuming the occurrence of 5 H2O groups and 1 (F+OH) atom per formula unit, its chemical formula can be written as Al0.96S1.02O4[F0.84(OH)0.16]Σ1.00⋅5H2O. The Raman spectrum of khademite is characterised by the occurrence of vibrational modes of SO4 groups and by broad and strong bands due to the O–H stretching modes. Khademite is orthorhombic, space group Pcab, with unit-cell parameters a = 11.1713(2), b = 13.0432(3), c = 10.8815(2) Å, V = 1585.54(5) Å3 and Z = 8. The crystal structure refinement converged to R1 = 0.0293 on the basis of 2359 unique reflections with Fo > 4σ(Fo) and 152 refined parameters. The crystal structure of khademite is characterised by the alternation, along b, of two distinct kinds of {010} layers, one formed by [001] rows of isolated Al-centred octahedra, connected to each other through H bonds, and the other showing isolated SO4 groups. Along b, oxygen atoms belonging to SO4 groups act as acceptor of H bonds from H2O groups coordinating Al atoms. The new data improved the description of the H bonds in khademite and led us to discuss about the possible existence of its (OH)-analogue, rostite. In addition, Raman spectroscopic data were collected on the same crystal used for the crystal-chemical characterisation, allowing a comparison with previous results. [ABSTRACT FROM AUTHOR]

The new alluaudite-group mineral badalovite was found in the Arsenatnaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. It is associated with hematite, tenorite, cassiterite, johillerite, nickenichite, calciojohillerite, bradaczekite, metathénardite, aphthitalite, langbeinite, calciolangbeinite, sanidine, fluorophlogopite, fluoborite, tilasite, anhydrite, pseudobrookite, sylvite, halite, lammerite, urusovite, ericlaxmanite, arsmirandite, svabite, krasheninnikovite, euchlorine, wulffite and alumoklyuchevskite. Badalovite forms oblique-angled prismatic crystals up to 1 mm × 1 mm × 5 mm, typically combined in groups or crusts up to several hundred cm2 in area. The mineral is transparent, green, grey, yellow or colourless, with vitreous lustre. It is brittle, the Mohs hardness is 3½. Cleavage was not observed, the fracture is uneven. Dcalc is 4.02 g cm–3. Badalovite is optically biaxial (–), α = 1.753(3), β = 1.757(3), γ = 1.758(3) and 2Vmeas. = 50(10)°. Chemical composition (wt.%, electron-microprobe; holotype) is: Na2O 9.23, K2O 0.19, CaO 2.04, MgO 13.78, MnO 0.31, CuO 0.12, ZnO 0.24, Al2O3 0.06, Fe2O3 12.77, TiO2 0.01, SiO2 0.06, P2O5 0.33, V2O5 0.05, As2O5 61.51, SO3 0.02, total 100.72. The empirical formula based on 12 O apfu is Na1.67Ca0.20K0.02Mg1.92Zn0.02Mn0.02Cu0.01Fe3+0.90Al0.01(As3.01P0.03Si0.01)Σ3.05O12. The simplified formula is Na2Mg2Fe3+(AsO4)3. Badalovite is monoclinic, C2/c, a = 11.9034(3), b = 12.7832(2), c = 6.66340(16) Å, β = 112.523(3)°, V = 936.59(4) Å3 and Z = 4. The strongest reflections of the powder XRD pattern [d,Å(I)(hkl)] are: 6.41(38)(020), 5.505(20)(200), 3.577(23)($\bar{1}$ 31), 3.523(25)(310), 3.211(46)($\bar{1}$ 12), 2.911(28)($\bar{2}$ 22, $\bar{3}$ 12), 2.765(100)(240, 400) and 2.618(26)($\bar{1}$ 32). The crystal structure was solved from single-crystal XRD data with an R1 of = 2.49%. Badalovite is isostructural with other alluaudite-group minerals. Its simplified crystal chemical formula is A(1)NaA(1)'□A(2) □A(2)'NaM(1)MgM(2)(Mg0.5Fe3+0.5)2(AsO4)3 (□ – vacancy) and the end-member formula is NaNaMg(MgFe3+)(AsO4)3. The mineral is named in honour of the outstanding mineralogist and geochemist Stepan Tigranovich Badalov (1919–2014). [ABSTRACT FROM AUTHOR]

Tetrahedrite-(Hg), Cu6(Cu4Hg2)Sb4S13, has been approved as a new mineral species using samples from Buca della Vena mine (hereafter BdV), Italy, Jedová hora (Jh), Czech Republic and Rožňava (R), Slovakia. It occurs as anhedral grains or as tetrahedral crystals, black in colour, with metallic lustre. At BdV it is associated with cinnabar and chalcostibite in dolomite veins. At Jh, tetrahedrite-(Hg) is associated with baryte and chalcopyrite in quartz–siderite–dolomite veins; at R it is associated with quartz in siderite–quartz veins. Tetrahedrite-(Hg) is isotropic, greyish-white in colour, with creamy tints. Minimum and maximum reflectance data for Commission on Ore Mineralogy wavelengths in air (BdV sample), R in %) are 32.5 at 420 nm; 32.9 at 546 nm; 33.2 at 589 nm; and 30.9 at 650 nm. Chemical formulae of the samples studied, recalculated on the basis of 4 (As + Sb + Bi) atoms per formula unit, are: (Cu9.44Ag0.07)Σ9.51(Hg1.64Zn0.36Fe0.06)Σ2.06Sb4(S12.69Se0.01)Σ12.70 (BdV), Cu9.69(Hg1.75Fe0.25Zn0.06)Σ2.06(Sb3.94As0.06)S12.87 (Jh) and (Cu9.76Ag0.04) Σ9.80(Hg1.83Fe0.15Zn0.10)Σ2.08(Sb3.17As0.58Bi0.25)S13.01 (R). Tetrahedrite-(Hg) is cubic, I $\overline 4 $ 3m, with a = 10.5057(8) Å, V = 1159.5(3) Å3 and Z = 2 (BdV). Unit-cell parameters for the other two samples are a = 10.4939(1) Å and V = 1155.61(5) Å3 (Jh) and a = 10.4725(1) Å and V = 1148.55(6) Å3 (R). The crystal structure of tetrahedrite-(Hg) has been refined by single-crystal X-ray diffraction data to a final R1 = 0.019 on the basis of 335 reflections with Fo > 4σ(Fo) and 20 refined parameters. Tetrahedrite-(Hg) is isotypic with other members of the tetrahedrite group. Mercury is hosted at the tetrahedrally coordinated M(1) site, along with minor Zn and Fe. The occurrence of Hg at this position agrees both with the relatively large M(1)–S(1) bond distance (2.393 Å) and the refined site scattering. Previous occurrences of Hg-rich tetrahedrite and tetrahedrite-(Hg) are reviewed, and its relations with other Hg sulfosalts are discussed. [ABSTRACT FROM AUTHOR]

Coquimbite, AlFe3+3(SO4)6(H2O)12⋅6H2O, was considered as a pure Fe3+ hydrated sulfate. However, previous mineralogical studies pointed out the occurrence of essential Al, occupying a distinct site in the crystal structure of this mineral. Through the critical re-examination of the available literature and new crystal-chemical data collected on a specimen from the Monte Arsiccio mine, Apuan Alps, Tuscany, Italy, the chemical formula of coquimbite has been revised, taking into account the occurrence of Al. Coquimbite has a homeotypic relationship with paracoquimbite, Fe4(SO4)6(H2O)12⋅6H2O; both mineral species belong to the coquimbite group. On the contrary, aluminocoquimbite, Al2Fe2(SO4)6(H2O)12⋅6H2O, has a different topology and does not belong to that group. [ABSTRACT FROM AUTHOR]

This paper presents the nomenclature of the rhodonite group accepted by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA). An overview of the previous studies of triclinic (space group P $\bar{1}$) pyroxenoids belonging to the rhodonite structure type, with a focus on their crystal chemistry, is given. These minerals have the general structural formula VII M (5)VI M (1)VI M (2)VI M (3)VI M (4)[Si5O15]. The following dominant cations at the M sites are known at present: M (5) = Ca or Mn2+, M (1–3) = Mn2+; and M (4) = Mn2+ or Fe2+. In accordance with the nomenclature, the rhodonite group consists of three IMA-approved mineral species having the following the general chemical formulae: M (5)A M (1–3)B3 M (4)C[Si5O15], where A = Ca or Mn2+; B = Mn2+; and C = Mn2+ or Fe2+. The end-member formulae of approved rhodonite-group minerals are as follows: rhodonite CaMn3Mn[Si5O15]; ferrorhodonite CaMn3Fe[Si5O15]; and vittinkiite MnMn3Mn[Si5O15]. [ABSTRACT FROM AUTHOR]

Hitachiite, Pb5Bi2Te2S6, is a new mineral discovered in the Hitachi mine, located in the Ibaraki Prefecture of Japan. The mean of 21 electron microprobe analyses gave: Pb 52.01, Bi 23.06, Fe 0.69, Sb 0.17, Te 13.74, S 9.71, Se 0.54, total 100.04 wt.%. The empirical chemical formula based on 15 apfu is (Pb4.75Fe0.23)Σ4.98(Bi2.09Sb0.03)Σ2.12Te2.04(S5.73Se0.13)Σ5.86, ideally Pb5Bi2Te2S6. Synchrotron single-crystal X-ray diffraction experiments indicated that hitachiite has trigonal symmetry, space group P ${\bar 3}$ m 1, with a = 4.2200(13) Å, c = 27.02(4) Å and Z = 1. The four strongest diffraction peaks shown in the powder X-ray pattern [ d , Å (I)(hkl)] are: 3.541(35)(012), 3.391(59)(013), 3.039(100)(015) and 2.114(56)(110). The calculated density (D calc) for the empirical chemical formula is 7.54 g/cm3. The crystal structure of hitachiite has been refined using synchrotron single-crystal X-ray diffraction data, to R = 7.38% and is based on ABC -type stacking of 15 layers (five Pb, two Bi, two Te, and six S layers) along the [001] direction, and with each layer ideally containing only one kind of atom. The stacking sequence is described as Te–Bi–S–Pb–S–Pb–S–Pb–S–Pb–S–Pb–S–Bi–Te. The discovery of hitachiite implies that the minerals of the Bi2Te2S–PbS join might form a homologous series of Bi2Te2S· n PbS. [ABSTRACT FROM AUTHOR]

The crystal structure of tlapallite has been determined using single-crystal X-ray diffraction and supported by electron probe micro-analysis, powder diffraction and Raman spectroscopy. Tlapallite is trigonal, space group P 321, with a = 9.1219(17) Å, c = 11.9320(9) Å and V = 859.8(3) Å3, and was refined to R 1 = 0.0296 for 786 reflections with I > 2σ(I). This study resulted from the discovery of well-crystallised tlapallite at the Wildcat prospect, Utah, USA. The chemical formula of tlapallite has been revised to (Ca,Pb)3CaCu6[Te4+3Te6+O12]2(Te4+O3)2(SO4)2·3H2O, or more simply (Ca,Pb)3CaCu6Te4+8Te6+2O30(SO4)2·3H2O, from H6(Ca,Pb)2(Cu,Zn)3(TeO3)4(TeO6)(SO4). The tlapallite structure consists of layers containing distorted Cu2+O6 octahedra, Te6+O6 octahedra and Te4+O4 disphenoids (which together form the new mixed-valence phyllotellurate anion [Te4+3Te6+O12]12−), Te4+O3 trigonal pyramids and CaO8 polyhedra. SO4 tetrahedra, Ca(H2O)3O6 polyhedra and H2O groups fill the space between the layers. Tlapallite is only the second naturally occurring compound containing tellurium in both the 4+ and 6+ oxidation states with a known crystal structure, the other being carlfriesite, CaTe4+2Te6+O8. Carlfriesite is the predominant secondary tellurium mineral at the Wildcat prospect. We also present an updated structure for carlfriesite, which has been refined to R 1 = 0.0230 for 874 reflections with I > 2σ(I). This updated structural refinement improves upon the one reported previously by refining all atoms anisotropically and presenting models of bond valence and Te4+ secondary bonding. [ABSTRACT FROM AUTHOR]

K-rich nepheline with a structural formula of A 2 B 6 T 14 T 24 T 34 T 44O32 (Z = 1) within melilite–olivine nephelinite from Hamada, Shimane Prefecture, Japan, was investigated to clarify its crystal structure and to determine cation distributions in the A and B structural positions of structural channels and tetrahedral T 1– T 4 sites. The chemical formula of a single-crystal sample was (Na5.437K2.248Mg0.034Ca0.031)Σ7.750(Si8.332Al7.445Fe3+0.158Ti0.009Cr0.005)Σ15.949O32, which results in 65.2, 27.8, 2.1, 3.2 and 1.6 mol.% NaAlSiO4, KAlSiO4, NaFe3+SiO4, □Si2O4 and □0.5(Ca,Mg)0.5AlSiO4 end-member components, respectively, where □ is a vacancy. X-ray diffraction data of a single crystal with dimensions of 0.28 mm × 0.15 mm × 0.05 mm measured at 296 K indicate the space group P 63. In the structural refinement, the R 1 factor was reduced to 3.69% by taking twinning by merohedry into the refinement. The refinement accounted for 77.7% of the absolute structure and 22.3% of the a and b axes reversed absolute structure. The atomic populations determined in the A and B positions were 1.834 K + 0.166 □ and 5.705 Na + 0.198 K + 0.031 Ca + 0.034 Mg, respectively, implying the substitution of K for Na in the B position. The a and c dimensions are a = 10.0270(3) and c = 8.4027(3) Å. The average < A –O> and < B –O> distances are 3.009 and 2.65 Å, respectively. The substitution of K for Na in the B channel results in increased volume and bond-length distortion of the B O8 polyhedra, which then reduces distortion of the A O9 polyhedra. The average T –O distances indicate that the T 1 and T 4 sites are essentially filled with Al, whereas the T 2 and T 3 are filled with Si. Despite the deviation of the O1 oxygen from the triad axis and the combination of K+ ions and vacancies in the hexagonal channels, an incommensurate structure was not observed in the X-ray diffraction data or using the electron diffraction technique. [ABSTRACT FROM AUTHOR]

The crystal structure of vigrishinite, ideally NaZnTi4(Si2O7)2O3(OH)(H2O)4, a murmanite-group mineral of the seidozerite supergroup from the type locality, Mt. Malyi Punkaruaiv, Lovozero alkaline massif, Kola Peninsula, Russia, was refined in space group C $\bar 1$ , a = 10.530(2), b = 13.833(3), c = 11.659(2) Å, α = 94.34(3), β = 98.30(3), γ = 89.80(3)°, V = 1675.5(2.1) Å3 and R 1 = 12.52%. Based on electron-microprobe analysis, the empirical formula calculated on 22 (O + F), with two constraints derived from structure refinement, OH + F = 1.96 pfu and H2O = 3.44 pfu, is: (Na0.67Zn0.21Ca0.05□1.07)Σ2 (Zn0.86□1.14)Σ2(Zn0.14□0.36)Σ0.5(Ti2.60Nb0.62Mn0.30 ${\rm Fe}_{{\rm 0}{\rm. 23}}^{{\rm 2 +}} $ Mg0.10Zr0.06Zn0.05Al0.03Ta0.01)Σ4(Si4.02O14) [O2.60(OH)1.21F0.19]Σ4[(H2O)3.44(OH)0.56]Σ4{Zn0.24P0.03K0.03Ba0.02} with Z = 4. It seems unlikely that constituents in the {} belong to vigrishinite itself. The crystal structure of vigrishinite is an array of TS blocks (Titanium Silicate) connected via hydrogen bonds. The TS block consists of HOH sheets (H = heteropolyhedral and O = octahedral) parallel to (001). In the O sheet, the Ti-dominant M O(1,2) sites, Na-dominant M O(3) and □-dominant M O(4) sites give ideally Na□Ti2 pfu. In the H sheet, the Ti-dominant M H(1,2) sites, Zn-dominant AP (1) and vacant AP (2) sites give ideally Zn□Ti2 pfu. The MH and A P (1) polyhedra and Si2O7 groups constitute the H sheet. The ideal structural formula of vigrishinite of the form ${\rm A}_{\rm 2}^{P} {\rm M}_{\rm 2}^{\rm H} {\rm M}_{\rm 4}^{\rm O} $ (Si2O7)2(${\rm X}_{\rm M}^{\rm O} $)2(${\rm X}_{\rm A}^{\rm O} $)2(${\rm X}_{{\rm M,A}}^{P} $)4 is Zn□Ti2Na□Ti2(Si2O7)2O2O(OH)(H2O)4. Vigrishinite is a Zn-bearing, Na-poor and OH-rich analogue of murmanite, ideally Na2Ti2Na2Ti2(Si2O7)2O2O2(H2O)4. Murmanite and vigrishinite are related by the following substitution: H(${\rm Na}_{\rm 2}^{\rm +} $)mur + O(Na+)mur + O(O2–)mur ↔ H(Zn2+)vig + H(□)vig + O(□)vig + O[(OH)–]vig. The doubling of the t 1 and t 2 translations of vigrishinite compared to those of murmanite is due to the order of Zn and □ in the H sheet and Na and □ in the O sheet of vigrishinite. [ABSTRACT FROM AUTHOR]

The crystal structure of the mineral gortdrumite, a rare copper-mercury-iron sulfide, was solved using intensity data collected using a crystal from the Neuschurf adit, Leogang, Salzburg, Austria. This study revealed that the structure is triclinic, space group P $\bar 1$ , with cell parameters: a = 9.677(4), b = 9.865(5), c = 11.992(5) Å, α = 77.85(4), β = 79.42(3), γ = 76.30(4)°, V = 1076.5(8) Å3 and Z = 1. The refinement led to an R index of 0.0833 for 3335 independent reflections and 143 parameters. Twelve S sites (one with half occupancy) and eighteen metal sites (5 Hg, 12 Cu and 1 Fe) occur in the crystal structure of gortdrumite. Mercury cations link two sulfur atoms in a linear coordination, Cu cations are found in various low-coordination (2, 3 and 4) sites, in agreement with the Cu preference for such environments, and Fe in tetrahedral coordination. Metal–metal interactions are also present and these contacts are discussed in relation with other copper sulfides, intermetallics and pure metals. Electron microprobe analyses of the crystal used for the structural study led to the formula Cu24.83Fe1.73Hg9.09S22.35, on the basis of 58 atoms. On the basis of information gained from the structural and chemical characterization, the crystal-chemical formula was revised to Cu24Fe2Hg9S23 (Z = 1) instead of (Cu,Fe)6Hg2S5 as reported previously. [ABSTRACT FROM AUTHOR]

The crystal structure of the mineral mertieite-II from the Kaarreoja River, Inari commune, Finnish Lapland, Finland, was refined to R1 = 0.0222 (I) and 0.0228 (II) on the basis of X-ray diffraction data collected from two single crystals. The mineral is trigonal, space group is R-3c. The unit-cell parameters for the two crystals are determined as: a = 7.5172(3), c = 43.037(2) Å, V = 2106.1(2) ų (I); a = 7.5135(4), c = 43.003(3) Å, V = 2102.4(3) ų (II) with Z = 12. The occupancies of the Sb and As position in the structure were refined according to the Sb:As ratio of each crystal. The position As1 (Wyckoff 6b) is completely filled by As atoms. Any excess of As is distributed together with Sb on structural positionM1 (Wyckoff 12c). The crystal chemical formulae are defined as Pd8Sb1.5(Sb0.94As0.06)As0.5 (crystal I) and Pd8Sb1.5(Sb0.88As0.12)As0.5 (crystal II). As-Sb substitution of up to 4.50 wt% of As does not affect the main structural topology of mertieite-II. Mertieite-II, Pd8Sb2.5As0.5 and synthetic Pd8Sb3 are isotypic compounds. The crystal structures of synthetic Pd8Sb3 and natural mertieite-II, Pd8Sb2.5As0.5, can be derived from the hexagonal close packing by filling additional layers between the close-packed 36 layers. The structure consists of Sb and (Sb,As) triangular 36, Pd triangular 36 and Pd pentagonal-triangular 5.33 layers. Stacking of Sb-, (Sb,As)- and Pdnets along the z axis caused extension of the unit cell. It contains a total of 36 layers: six Sb1-nets, six (M1, As1)-nets, 12 Pd1-nets and 12 (Pd1,Pd3,Pd4)-nets. [ABSTRACT FROM AUTHOR]

Embreyite from the Berezovskoe, Urals, Russia, was studied by the means of powder X-ray diffraction (XRD), single-crystal XRD, infrared spectroscopy and microprobe analysis. The empirical formula of embreyite obtained on the basis of microprobe analysis is Pb1.29Cu0.07Cr0.52P0.43O4 (without taking into account the presence of H2O). An examination of single-crystal XRD frames of the tested crystals cut from embreyite intergrowths revealed split reflection spots of weak intensities, even after a long exposure time. The crystal structure of embreyite (monoclinic, C 2/ m , a = 9.802(16), b = 5.603(9), c = 7.649(12) Å, β = 114.85(3)o and V = 381.2(11) Å3) has been solved by direct methods and refined to R 1 = 0.050 for 318 unique observed reflections. The powder XRD patterns of the holotype embreyite and the fresh material studied are close in both d values and the intensities match the pattern calculated from the structural single-crystal XRD data. The unit-cell parameters were re-calculated for the holotype sample using a new cell setting and corresponding hkl indices. The crystal structure of embreyite is based on layers formed by corner-sharing mixed chromate-phosphate tetrahedra and PbO6 distorted octahedra. The interlayer space is filled by disordered Pb2+ and Cu2+ cations. Generally, the crystal structure of embreyite can be referred to the structural type of palmierite. {Pb[(Cr,P)O4]2]} layers in embreyite are similar in topology to those in yavapaiite-type compounds. The general formula of embreyite can be represented as (Pb x $M_y^{2 +} $ □1 –x– y )2{Pb[(Cr,P)O4]2}(H2O) n , where M 2+ = Cu and Zn and 0.5 ≤ x + y ≤ 1, or, in the simplified form: (Pb,Cu,□)2{Pb[(Cr,P)O4]2}(H2O) n . The simplified formula of embreyite is similar in stoichiometry to vauquelinite and may explain the existence of the solid-solution series. The determination of the crystal structure of embreyite may also help to resolve the crystal chemical nature of cassedanneite. The XRD pattern of cassedanneite contains a distinct reflection with d = 13.9 Å, forbidden for the embreyite unit cell. This feature may indicate the doubling of the c unit-cell parameter of cassedanneite in comparison with embreyite. We assume that cassedanneite has structural similarity to embreyite with, presumably, a disordered distribution of Cr and V. [ABSTRACT FROM AUTHOR]

The crystal structure and the chemical composition of uklonskovite from the holotype material was reinvestigated to shed light on its correct chemical formula. On the basis of information gained from this characterization, we revised the formula from NaMg(SO4)OH·2H2O to NaMg(SO4)F·2H2O (F instead of OH). A careful analysis of the structural details together with a critical review of all the chemical data listed in the scientific literature for uklonskovite support our redefinition. We also present Raman data for the mineral for the first time. Our proposal was approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (voting proposal 16-J). [ABSTRACT FROM AUTHOR]

A crystal chemical study of narsarsukite from the Murun alkaline massif, Russia has been carried out combining single-crystal X-ray diffraction, electron microprobe analyses, micro-Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The narsarsukite single crystals are tetragonal (space group I4/m) with unit-cell parameters: 10.7140(1) ≤ a ≤ 10.7183(2) Å and 7.9478(1) ≤ c ≤ 7.9511(1) Å. The XPS analysis showed that Fe occurs in the mineral as Fe3+, whereas the FTIR spectrum showed that the sample studied is anhydrous. The average crystal chemical formula of the Murun narsarsukite is: Na2.04K0.01(V5+0.01Ti0.74Zr0.01Al0.01Fe3+0.22Mg0.01)1.00Si4.00(O10.74F0.23OH0.03)11.00. Structural disorder at octahedral and interstitial sites was modelled and also discussed in consideration of the main substitutional mechanism Ti4+ + O2− ↔ Fe3+ + (F−, OH−) active in the structure of the mineral. [ABSTRACT FROM AUTHOR]

A multi-methodological study of the (K,Ca)-variety of the zeolite merlinoite from Fosso Attici, Sacrofano, Italy was carried out on the basis of electron microprobe analysis in wavelength dispersive mode, singlecrystal X-ray diffraction (at 100 K), Raman and infrared spectroscopy. The chemical formula of the merlinoite from Fosso Attici is (Na0.37K5.69)Σ=6.06(Mg0.01Ca1.93Ba0.40)Σ=2.34(Fe3+ 0.02Al10.55Si21.38)Σ=31.9O64· 19.6H2O, compatible with the ideal chemical formula K6Ca2[Al10Si22O64]·20H2O. Anisotropic structure refinements confirmed the symmetry and the framework model previously reported (space group Immm, a = 14.066(5),b = 14.111(5), c = 9.943(3) Å at 100 K). Refinement converged with four cationic sites and six H2O sites; refined bond distances of the framework tetrahedra suggest a highly disordered Si/ Al-distribution. The Raman spectrum of merlinoite (collected between 100 and 4000 cm−1) is dominated by a doublet of bands between 496−422 cm−1, assigned to tetrahedral T-O−T symmetric bending modes. T−O−T antisymmetric stretching is also observed; stretching and bending modes of the H2O molecules are only clearly visiblewhen using a blue laser. The single-crystal near-infrared spectrum shows a very weak band at 6823 cm−1, assigned to the first overtone of the O−H stretching mode, and a band at 5209 cm−1, due to the combination of H2O stretching and bendingmodes.Avery broad and convoluted absorption, extending from 3700 to 3000 cm−1 occurs in the H2O stretching region, while the ν2 bending mode of H2O is found at 1649 cm−1. The powder midinfrared spectrum of merlinoite between 400−1300 cm−1 is dominated by tetrahedral T−O−T symmetric and antisymmetric stretches. Raman and Fourier-transform infrared spectroscopy spectra of merlinoite and phillipsite provide a quick identification tool for these zeolites, which are often confused due to their close similarity. [ABSTRACT FROM AUTHOR]

The members of the sartorite homologous series are complex sulfides Me2+8N - 16 - 2XMe3+16+XMe+XS8N+8 where Me2+ is Pb and Me3+ is As and Sb, whereas Me+ is Ag and/or Tl. This paper presents calculation formulae for the homologue order N and for the separate substitution percentages for Tl + (As,Sb) ↔ 2Pb and Ag + (As,Sb) ↔ 2Pb substitutions. This enables one to evaluate the crystal chemistry and build a systematic classification of the sartorite homologues. [ABSTRACT FROM AUTHOR]

The crystal structure of burckhardite from the type locality, Moctezuma, Sonora, Mexico, has been refined to R1= 0.0362 and wR2= 0.0370 for 215 reflections with I> 2σ(I). Burckhardtite is trigonal, space group P31m, with the unit-cell parameters a= 5.2566(5) Å, c= 13.0221(10) Å, V= 311.62(5) Å3and Z= 1 for the ideal formula unit Pb2(Fe3䷮)[AlSi3O8]O6. There is no long-range order of (Fe3, Te6) or (Al3, Si4). New microprobe data were used to estimate site scattering factors, and Raman spectroscopic data showed no evidence of O–H stretching bands. Burckhardtite is not closely related to the micas, as supposed previously, but is a double-sheet silicate in which the aluminosilicate anion resembles that of minerals such as cymrite and kampfite. The [(Fe3䷮)O6]3–part of the structure is not bonded directly to the aluminosilicate layer, but forms a discrete anionic phyllotellurate layer that alternates with the [AlSi3O8]–double sheets. Similar phyllotellurate layers are known from several synthetic phases. In burckhardtite, Pb2熫抢 intercalate between phyllosilicate and phyllotellurate layers, forming a Pb2[FeTeO6] module that is topologically similar to a slab of the structure of rosiaite, Pb[Sb2O6]. The crystal symmetry, structure, classification as a double-sheet silicate and chemical formula, including the determination of the 6 valence of Te and absence of essential H2O, are all new findings for the mineral. [ABSTRACT FROM AUTHOR]

Tondiite, with the simplified formula Cu3Mg(OH)6Cl2, occurs as a rare supergene mineral in a phonolitic tephrite from the type locality, Vesuvius volcano, Italy, as well as associated with haydeeite in the Santo Domingo Mine, Arica Province, Chile. It is emerald green to bright green in colour and occurs in irregularly shaped crystals, often with stepped faces. Its calculated density is 3.503 g cm–3. Tondiite crystallizes with the herbertsmithite structure type, space group R3m. Lattice parameters are a= 6.8377(7) Å and c= 14.088(2)Å for the holotype material. The cparameter may vary with Mg/Cu ratio and the presence of impurity atoms. The five strongest lines in the calculated powder diffraction pattern are [din Å(I)(hkil)]: 5.459(88)(1011), 3.419(22)(1120), 2.764(100)(1123), 2.266(54)(0224), 1.706(26)(2240). Several tondiite crystals have been examined by single-crystal X-ray diffraction and by electron microprobe analysis. The observed Mg content ranges between 0.6 and 0.7 atoms per formula unit. The structural role of Mg is discussed. [ABSTRACT FROM AUTHOR]

Wakabayashilite is a rare mineral with ideal formula [(As, Sb)6S9][As4S5]. Its structure consists of an [M6S9] bundle-like unit (M = As, Sb) running along the [001] axis and [As4S5] cage-like molecules. In this study, samples of wakabayashilite from different occurrences (Khaidarkan, Kyrgyzstan; Jas Roux, France; White Caps mine, USA; Nishinomaki mine, Japan) were selected to verify the possible presence of different molecular groups replacing the As4S5molecule. Given the chemical (electron probe microanalysis-wavelength dispersive spectroscopy), spectroscopic (micro-Raman) and structural (single-crystal X-ray diffraction) results obtained, it appears evident that only the As4S5molecular group is present in the wakabayashilite structure and that the apparent non-stoichiometry reported in literature is actually due to unreliable chemical analyses. The structural role of the minor elements (Cu, Zn and Tl) in wakabayashilite is also discussed. [ABSTRACT FROM AUTHOR]

The new mineral oskarssonite (IMA2012-088), with ideal formula AlF3, was found in August 2009 at the surface of fumaroles on the Eldfell volcano, Heimaey Island, Iceland (GPS coordinates 63°25'58.9''N 20°14'50.3''W). It occurs as sub-micron-sized crystals forming a white powder in association with anhydrite, bassanite, gypsum, jarosite, anatase, hematite, opal, ralstonite, jakobssonite and meniaylovite. Chemical analyses by energy-dispersive spectrometry with a scanning electron-microscope produced the following mean elemental composition: Al, 31.70; F, 58.41; O, 9.22; total 99.33 wt.%. The empirical chemical formula is AlF2.6(OH)0.5which suggests partial substitution of F by OH. Oskarssonite is rhombohedral, space group R3c, with ah= 4.9817(4) Å, c= 12.387(1) Å, Vuc= 266.23(5) Å3, Z= 6. The five strongest lines in the powder diffraction diagram [d in Å (I) (hkl)] are as follows: 3.54 (100) (012), 2.131 (13) (113), 1.771 (20) (024), 1.59 (15) (116), 1.574 (10) (122). Rietveld refinement confirms the identity of oskarssonite with the synthetic rhombohedral form of AlF3. Its structure can be described as a rhombohedral deformation of the idealized cubic perovskitetype octahedral framework of corner-sharing AlF6 groups. Oskarssonite appears in the surface part of the fumaroles where fluorides are abundant. At greater depths (below 10 cm) sulfates dominate among the fumarolic minerals. In accordance with its occurrence, we surmise that oskarssonite forms in the later stages of the fumarolic activity in an environment poor in alkalies and Mg. Ralstonite (NaxMgxAl1–xF3(H2O)y), which, unlike oskarssonite, contains Na and Mg as important constituents, dominated in the first-formed fumaroles, but now, 41 years after the eruption of Eldfell, is only a minor phase. The new mineral is named after the Icelandic volcanologist Niels Oskarsson. [ABSTRACT FROM AUTHOR]

Electron microprobe analysis of barikaite (Topa et al., 2013) indicates the chemical formula Ag2.90Tl0.04Pb9.31As11.26Sb8.12S40.37. Barikaite is monoclinic, with a8.533(1) Å, b8.075(1) Å, c24.828(2) Å, and β 99.077(1)°; unit-cell volume 1689.2 Å3and the space-group setting is P21/n. This compares well with the unit-cell parameters of rathite Pb10Tl0.9As17.9Sb1.3Ag2S40from the Lengenbach deposit with the same lattice setting. Barikaite is a member of sartorite homologous series (N = 4). The unit cell of barikaite contains eight cation sites and ten anion sites. Four of the cation sites have mixed occupancies – the split sites As2 Sb2, As3 Sb3, Ag5 As5 and the siteMe6 with three cations involved. Two of the lead sites, Pb1 and Pb2, display tricapped trigonal prismatic coordinations and alternate along the 8.53 Å adirection. They form zig-zag walls parallel to (001). There are three distinct [100] columns of alternating cations, As1 (As, Sb)2, Sb4 (As, Sb)3 and (As, Ag)5 (Pb, Sb)6 which together form trapezoidally configured single (013) layers. These layers aggregate into tightlybonded double layers, separated by lone electron pair micelles. In barikaite, the predominantly As-occupied and Sb-occupied sites are distributed in a chess-board-like scheme. [ABSTRACT FROM AUTHOR]

Dervillite, As2AsS2, has been found in a sample from the Lengenbach quarry in the Binn Valley, Valais, Switzerland. It occurs as very rare crystals up to 200 μm across on jordanite. Dervillite is opaque with a metallic lustre and shows a dark brown streak. The structure is monoclinic, space group Pc, with a= 9.6155(7), b= 12.9331(8), c= 6.8616(5) A , b = 99.352(8)º, V= 842.0(1) Å3and Z= 8. In the crystal structure [R1= 0.060 for 2370 reflections with I> 2σ(I)], silver adopts various coordinations extending from quasi linear to quasi tetrahedral whereas arsenic forms very peculiar crystal-chemical environments, such as As(S2As) and As(S2AsAg). Such metalloid–metalloid or metal–metalloid bonds account for the apparent charge imbalance observed in the chemical formula. [ABSTRACT FROM AUTHOR]

Zincalstibite-9R, a new polytype in the hydrotalcite supergroup is reported from the Monte Avanza mine, Italy. It occurs as pale blue curved disc-like tablets flattened on {001} intergrown to form rosettes typically less than 50 μm in diameter, with cyanophyllite and linarite in cavities in baryte. Zincalstibite-9Ris uniaxial (–), with refractive indices ω = 1.647(2) and = 1.626(2) measured in white light. The empirical formula (based on 12 OH groups) is (Zn2+1.09Cu2+0.87Al0.04)Σ2.00Al1.01(Sb5+0.97Si0.02)Σ0.99(OH)12, and the ideal formula is (Zn,Cu)2Al(OH)6[Sb(OH)6]. Zincalstibite-9Rcrystallizes in space group R3, witha= 5.340(2),c= 88.01(2) Å,V= 2173.70(15) Å3and Z= 9. The crystal structure was refined to R1= 0.0931 for 370 unique reflections [Fo> 4σ(F)] and R1= 0.0944 for all 381 unique reflections. It has the longest periodic layer stacking sequence for a layered double hydroxide compound reported to date. [ABSTRACT FROM AUTHOR]

The crystal structure and chemical composition of two samples of fettelite from the type locality, including a portion of the holotype material, was investigated to verify if a previously proposed revision of the chemical formula was applicable, and to study the role of cation substitution for Hg that would suggest new members of the fettelite family. The crystal structure of fettelite from the type locality was found to be equivalent to that reported previously for the Chilean occurrence, and consists of an alternation of two kinds of layers along c: layer Awith general composition [Ag6As2S7]2–and layer Bwith general composition [Ag10HgAs2S8]2+. In this structure, the Ag atoms occur in various coordination configurations, varying from quasi-linear to quasi-tetrahedral, the AsS3groups form pyramids as are typically observed in sulfosalts, and Hg links two sulfur atoms in a linear coordination. The refined compositions for the crystals in this study, [Ag6As2S7][Ag10(Fe0.53Hg0.47)As2S8] (R100124) and [Ag6As2S7][Ag10(Hg0.79Cu0.21)As2S8] (R110042), clearly indicate that new mineral species related to fettelite are likely to be found in nature. [ABSTRACT FROM AUTHOR]

New electron-microprobe analyses of mayenite from the Ettringer Bellerberg volcano near Mayen in the Eifel district, Germany have high Cl contents and Raman spectroscopy indicates the presence of OH groups. Neither of these components is included in the generally accepted chemical formula, Ca12Al14O33. A refinement of the crystal structure by single-crystal X-ray methods reveals a previously unrecognized partial substitution. The O2 site which forms one of the apices of an AlO4tetrahedron (with 3 × O1 sites) is replaced by 3 × O2a sites, which change the coordination of the central Al atom from tetrahedral to octahedral. This substitution is related to partial hydration of Ca12Al14O32Cl2according to the isomorphic scheme (O2–+ Cl–) ↔ 3(OH)–. The revised composition of Eifel mayenite is best described by the formula Ca12Al14O32–xCl2–x(OH)3x(x∼0.75); the original formula, Ca12Al14O33, is inadequate. The analysed mineral can be considered to consist of endmember Ca12Al14O32Cl2(62.5 mol.%) and endmember Ca12Al14O30(OH)6(37.5 mol.%). [ABSTRACT FROM AUTHOR]

The composition, structure, X-ray powder diffraction pattern, optical properties, density, infrared, Raman and Mössbauer spectra, and thermal properties of a homogeneous sample of metavivianite from the Boa Vista pegmatite, near Galiléia, Minas Gerais, Brazil are reported for the first time. Metavivianite is biaxial (+) with α = 1.600(3), β = 1.640(3), γ = 1.685(3) and 2Vmeas= 85(5)°. The measured and calculated densities are Dmeas= 2.56(2) and Dcalc= 2.579 g cm–3. The chemical composition, based on electronmicroprobe analyses, Mössbauer spectroscopy (to determine the Fe2+:Fe3+ratio) and gas chromatography (to determine H2O) is MgO 0.70, MnO 0.92, FeO 17.98, Fe2O326.60, P2O528.62, H2O 26.5; total 101.32 wt.%. The empirical formula is (Fe3+1.64Fe2+1.23Mg0.085Mn0.06)Σ3.015(PO4)1.98(OH)1.72·6.36H2O. Metavivianite is triclinic, P1, a= 7.989(1), b= 9.321(2), c= 4.629(1) Å, α = 97.34(1), β = 95.96(1), γ = 108.59(2)°, V= 320.18(11) Å3and Z= 1. The crystal structure was solved using a single-crystal techniques to an agreement index R= 6.0%. The dominant cations in the independent sites are Fe2+and Fe3+, with multiplicities of 1 and 2, respectively. The simplified crystal-chemical formula for metavivianite is Fe2+(Fe3+, Fe2+)2(PO4)2(OH,H2O)2·6H2O; the endmember formula is Fe2+Fe3+2(PO4)2(OH)2·6H2O, which is dimorphous with ferrostrunzite. [ABSTRACT FROM AUTHOR]

The crystal structure of the rare skarn mineral trabzonite, Ca4[Si3O9(OH)]OH, from the type locality near Ikizdere, Turkey and from the Upper Chegem caldera, Northern Caucasus, Kabardino-Balkaria, Russia has been solved and refined using single-crystal X-ray data. This shows that the chemical formula should be modified from Ca4(Si3O10)2H2O, reported in the original trabzonite description, to an OH-bearing composition. The crystal structure, which contains Si3O10trimers embedded in a framework of CaO6–8polyhedra, has orthorhombic symmetry, space group Ama2, a= 20.6, b= 9.1, c= 10.3 Å. The orthorhombic A-centred cell is easily obtained by transformation from the original monoclinic cell of P21/msymmetry. The revised formula means that trabzonite and foshagite are polymorphs; foshagite has wollastonite-like silicate chains and in contrast to trabzonite it does not contain silanol groups.The structure and composition of killalaite from both localities was also studied. Single-crystal X-ray structure refinement of killalaite from the Northern Caucasus confirmed it to be non-stoichiometric with a composition between Ca6[Si2O6(OH)]2(OH)2and Ca7[Si2O7]2(OH)2(Z= 2). Trabzonite, killalaite and dellaite form a series of modular structures which differ mainly in the degree of condensation of the SiO4units. [ABSTRACT FROM AUTHOR]

The crystal structure of kyzylkumite, ideally Ti2V3+O5(OH), from the Sludyanka complex in South Baikal, Russia was solved and refined (including the hydrogen atom position) to an agreement index,R1, of 2.34% using X-ray diffraction data collected on a twinned crystal. Kyzylkumite crystallizes in space groupP21/c, witha= 8.4787(1),b= 4.5624(1),c= 10.0330(1) Å , b = 93.174(1)º,V= 387.51(1) Å3andZ= 4. Tivanite, TiV3+O3OH, and kyzylkumite have modular structures based on hexagonal close packing of oxygen, which are made up of rutile [TiO2] and montroseite [V3+O(OH)] slices. In tivanite the rutile:montroseite ratio is 1:1, in kyzylkumite the ratio is 2:1. The montroseite module may be replaced by the isotypic paramontroseite V4+O2module, which produces a phase with the formula Ti2V4+O6. In the metamorphic rocks of the Sludyanka complex, vanadium can be present as V4+and V3+within the same mineral (e.g.in batisivite, schreyerite and berdesinskiite). Kyzylkumite has a flexible composition with respect to the M4+/M3+ratio. The relationship between kyzylkumite and a closely related Be-bearing kyzylkumite-like mineral with an orthorhombic norbergite-type structure from Byrud mine, Norway is discussed. Both minerals have similar X-ray powder diffraction patterns. [ABSTRACT FROM AUTHOR]

The crystal structure of mendeleevite-(Ce), (Cs,〈)6(〈,Cs)6(〈,K)6(REE,Ca,〈)30(Si70O175)(H2O,OH,F,〈)35, a new mineral from the moraine of the Darai-Pioz glacier, the Alai mountain ridge, Tien-Shan mountains, northern Tajikistan, was solved by direct methods and refined to R1= 4.15% based on 2274 observed [Fo> 4σ|F|] unique reflections measured with Mo-Kα radiationona Bruker P4 diffractometer equipped with a CCD detector. Mendeleevite-(Ce) is cubic, space group Pm3, a21.9148(4) Å, V10525(1) Å3, Z= 2, Dcalc= 3.066 g/cm3. The empirical formula (electron microprobe) is Cs5.94K2.22[(Ce11.35La5.86Nd3.23Pr1.54Sm0.32Gd0.20)Σ22.50(Ca4.68Sr1.00)Σ5.68]Σ28.18Si70.12O203.17H45.67F6.83, Z= 2, calculated onthe basis of 210 (O + F) a.p.f.u., with H2O and OH calculated from structure refinement (OH + F = 17 p.f.u.; H2O = 17.75 p.f.u.).The structural formula is (Cs4.65〈1.35)Σ6(〈4.71Cs1.29)Σ6(〈3.78K2.22)Σ6{[(Ce11.35La5.86Nd3.23Pr1.54Sm0.32Gd0.20)Σ22.50(Ca4.68Sr1.00)Σ5.68]Σ28.18〈1.82}Σ30(Si70O175)[(OH)10.17F6.83]Σ17(H2O)17.75. Simplified and endmember formulae are as follows: (Cs,〈)6(〈,Cs)6(〈,K)6(REE,Ca,〈)30(Si70O175) (H2O,OH,F,〈)35and Cs6(REE22Ca6)(Si70O175)(OH,F)14(H2O)21. The crystal structure of mendeleevite(Ce) is an intercalation of two independent Si–O radicals and an M framework of (REE, Ca) polyhedra. The Si–O radicals are an(Si104O260)104–framework and an (Si36O90)36–cluster which do not link directly. The M framework is located betweenthe Si–O framework and the Si–O clusters. Interstitial cations occupy two types of cages and channels. Cages I and II are 78 and 22% occupied by Cs. Channels along [100@] contain K atoms and H2O groups. Mendeleevite-(Ce) has no natural or synthetic structural analogues. Mendeleevite-(Ce) is a framework mineral with large cavities and it has the potential to be used as a model for the synthesis of microporous materials of industrial interest. [ABSTRACT FROM AUTHOR]

Bariopharmacoalumite, ideally Ba0.5Al4(AsO4)3(OH)4·4H2O, is a new mineral from Cap Garonne, France. It occurs in several places within the mine as colourless to pale yellow interpenetrating cubes up to 0.5 mm across. Bariopharmacoalumite is transparent to translucent, with a white streak, has an adamantine lustre and imperfect cleavage on {001}. The Vickers hardness is 234.35 and the Mohs harness is 3.5. Bariopharmacoalumite is isotropic, with n= 1.573 (upper estimate) [calculated from reflectance values at 589 nm using Fresnel Equations]. The empirical formula, based on 20 oxygen atoms, is: (Ba0.54Cu0.03K0.01)Σ0.58(Al3.99Fe0.02)Σ4.01(AsO4)3.00(OH)3.85O0.15·4H2O and the calculated density (on the basis of the empirical formula and single-crystal unit cell) is 2.580 g/cm3. The four strongest lines in the X-ray powder diffraction pattern are [dobs(Å), Iobs,(hkl)]: 7.759, 100, (001); 5.485, 27, (011); 3.878, 27, (002); 4.454, 18, (011). Bariopharmacoalumite from Cap Garonne is cubic, space group P43mwith a= 7.742(4) Å, V= 464.2(4) Å3and Z = 1. The crystal structure was solved by direct methods and refined to R1= 0.0705 for 215 reflections with I> 4σ(I) and is consistent with members of the pharmacosiderite supergroup. Data are also presented from zoned bariopharmacoalumite–bariopharmacosiderite crystals found at the Mina Grande mine, Chile. [ABSTRACT FROM AUTHOR]

Hydroniumpharmacosiderite, ideally (H3O)Fe4(AsO4)3(OH)4·4H2O, is a new mineral from Cornwall, UK, probably from the St. Day group of mines. It occurs as a single yellowish green, slightly elongated cube, measuring 0.17 mm × 0.14 mm × 0.14 mm. The mineral is transparent with a vitreous lustre. It is brittle with a cleavage on {001}, has an irregular fracture, a white streak and a Mohs hardness of 2–3 (determined on H3O-exchanged pharmacosiderite). Hydroniumpharmacosiderite has a calculated density of 2.559 g cm–3for the empirical formula. The empirical formula, based upon 20.5 oxygen atoms, is: [(H3O)0.50K0.48Na0.06]1.04(Fe3.79Al0.22)4.01[(As2.73P0.15)2.88O12](OH)4·4H2.14O. The five strongest lines in the X-ray powder diffraction pattern are [dobs(Å), Iobs,(hkl)]: 8.050,100,(001); 3.265,35,(112); 2.412,30,(113); 2.830,23,(202); 4.628,22,(111). Hydroniumpharmacosiderite is cubic, space group P43mwith a= 7.9587(2) Å, V= 504.11(2) Å3and Z= 1. The crystal structure was solved by direct methods and refined to R1= 0.0481 for 520 reflections with I> 2σ(I). The structure is consistent with determinations for H3O-exhchanged pharmacosiderite and the general pharmacosiderite structure type. [ABSTRACT FROM AUTHOR]