Main Diffraction Lines Research Articles

Mechanical Grinding of Hydroxyapatite and Its Interaction with Titanium

The development of promising biocompatible composites based on hydroxyapatite with a metallic component is of great interest to researchers. This article describes the synthesis of hydroxyapatite powder by the hydrolytic method and presents the results of mechanical grinding of hydroxyapatite powder. Additionally, in order to study the interaction between titanium and hydroxyapatite powders, the results of their thermal treatment in the temperature range of 600–900 °C are presented. As a result of the hydrolytic method, a powder consisting of Ca5(PO4)3(OH) and CaO phases with a fraction of 400–600 μm was obtained. According to the results of mechanical grinding, it was determined that with an increase in grinding time from 30 to 120 min, the intensive main diffraction lines corresponding to hydroxyapatite decrease. During the thermal treatment of titanium and hydroxyapatite powders, titanium oxidizes forming suboxides and titanium dioxide (TiO2). At higher temperatures, the hydroxyapatite phase disappears from the mixture, and titanium oxide, calcium phosphate compound, and small amounts of calcium titanate and titanium hydrophosphate are present.

DyMnO3: Synthesis, Characterization and Evaluation of Its Photocatalytic Activity in the Visible Spectrum.

DyMnO3 is a p-type semiconductor oxide with two crystal systems, orthorhombic and hexagonal. This material highlights its ferroelectric and ferromagnetic properties, which have been the subject of numerous studies. Nevertheless, its photocatalytic activity has been less explored. In this work, the photocatalytic activity of DyMnO3 is evaluated through the photodegradation of MG dye. For the synthesis of this oxide, a novel and effective method was used: polymer-decomposition. The synthesized powders contain an orthorhombic phase, with a range of absorbances from 300 to 500 nm and a band gap energy of 2.4 eV. It is also highlighted that, when using this synthesis method, some of the main diffraction lines related to the orthorhombic phase appear at 100 °C. Regarding its photocatalytic activity, it was evaluated under visible light (λ = 405 nm), reaching a photodegradation of approximately 88% in a period of 30 min. Photocurrent tests reveal a charge carrier separation (e-,h+) at a 405 nm wavelength. The main reactive oxygen species (ROS) involved in the photodegradation process were radicals, OH•, and photo-holes (h+). These results stand out because it is the first time that the photodegradation capability of this oxide in the visible spectrum has been evaluated.

Rüdlingerite, Mn2+2V5+As5+O7·2H2O, a New Species Isostructural with Fianelite

The new mineral species rüdlingerite, ideally Mn2+2V5+As5+O7·2H2O, occurs in the Fianel mine, in Val Ferrera, Grisons, Switzerland, a small Alpine metamorphic Mn deposit. It is associated with ansermetite and Fe oxyhydroxide in thin fractures in Triassic dolomitic marbles. Rüdlingerite was also found in specimens recovered from the dump of the Valletta mine, Canosio, Cuneo, Piedmont, Italy, where it occurs together with massive braccoite and several other As- and V-rich phases in richly mineralized veins crossing the quartz-hematite ore. The new mineral displays at both localities yellow to orange, flattened elongated prismatic, euhedral crystals measuring up to 300 μm in length. Electron-microprobe analysis of rüdlingerite from Fianel gave (in wt%): MnO 36.84, FeO 0.06, As2O5, 25.32, V2O5 28.05, SiO2 0.13, H2Ocalc 9.51, total 99.91. On the basis of 9 O anions per formula unit, the chemical formula of rüdlingerite is Mn1.97(V5+1.17 As0.83Si0.01)Σ2.01O7·2H2O. The main diffraction lines are [dobs in Å (Iobs) hkl]: 3.048 (100) 022, 5.34 (80) 120, 2.730 (60) 231, 2.206 (60) 16-1, 7.28 (50) 020, 2.344 (50) 250, 6.88 (40) 110, and 2.452 (40) 320. Study of the crystal structure showcases a monoclinic unit cell, space group P21/n, with a = 7.8289(2) Å, b = 14.5673(4) Å, c = 6.7011(2) Å, β = 93.773(2)°, V = 762.58(4) Å3, Z = 4. The crystal structure has been solved and refined to R1 = 0.041 on the basis of 3784 reflections with Fo > 4σ(F). It shows Mn2+ hosted in chains of octahedra that are subparallel to [-101] and bound together by pairs of tetrahedra hosted by V5+ and As5+, building up a framework. Additional linkage is provided by hydrogen-bonding through H2O coordinating Mn2+ at the octahedra. One tetrahedrally coordinated site is dominated by V5+, T(1)(V0.88As0.12), corresponding to an observed site scattering of 24.20 electrons per site (eps), whereas the second site is strongly dominated by As5+,T(2)(As0.74V0.26), with, accordingly, a higher observed site scattering of 30.40 eps. The new mineral has been approved by the IMA-CNMNC and named for Gottfried Rüdlinger (born 1919), a pioneer in the 1960–1980s, in the search and study of the small minerals from the Alpine manganese mineral deposits of Grisons.

Crystal Chemistry of Sulfates from the Apuan Alps (Tuscany, Italy). V. Scordariite, K8(Fe3+0.67□0.33)[Fe3+3O(SO4)6(H2O)3]2(H2O)11: A New Metavoltine-Related Mineral

The new mineral species scordariite, K8(Fe3+0.67□0.33)[Fe3+3O(SO4)6(H2O)3]2(H2O)11, was discovered in the Monte Arsiccio mine, Apuan Alps, Tuscany, Italy. It occurs as pseudo-hexagonal tabular crystals, yellowish to brownish in color, up to 0.5 mm in size. Cleavage is perfect on {0001}. It is associated with giacovazzoite, krausite, gypsum, jarosite, alum-(K), and magnanelliite. Electron microprobe analyses give (wt %): SO3 47.31, Al2O3 0.66, Fe2O3 24.68, FeO 0.69, Na2O 0.52, K2O 17.36, H2Ocalc 15.06, total 106.28. The partitioning of Fe between Fe2+ and Fe3+ was based on Mössbauer spectroscopy. On the basis of 67 O atoms per formula unit, the empirical chemical formula is (K7.50Na0.34)Σ7.84(Fe3+6.29Al0.26Fe2+0.20)Σ6.75S12.02O50·17H2O. The ideal end-member formula can be written as K8(Fe3+0.67□0.33)[Fe3+3O(SO4)6(H2O)3]2(H2O)11. Scordariite is trigonal, space group R-3, with (hexagonal setting) a = 9.7583(12), c = 53.687(7) Å, V = 4427.4(12) Å3, Z = 3. The main diffraction lines of the observed X-ray powder pattern are [d(in Å), estimated visual intensity]: 8.3, strong; 6.6, medium; 3.777, medium; 3.299, medium; 3.189, medium; 2.884, strong. The crystal structure of scordariite has been refined using X-ray single-crystal data to a final R1 = 0.057 on the basis of 1980 reflections with Fo > 4σ(Fo) and 165 refined parameters. It can be described as a layered structure formed by three kinds of layers. As with other metavoltine-related minerals, scordariite is characterized by the occurrence of the [Fe3+3O(SO4)6(H2O)3]5− heteropolyhedral cluster.

Carmeltazite, ZrAl2Ti4O11, a New Mineral Trapped in Corundum from Volcanic Rocks of Mt Carmel, Northern Israel

The new mineral species carmeltazite, ideally ZrAl2Ti4O11, was discovered in pockets of trapped melt interstitial to, or included in, corundum xenocrysts from the Cretaceous Mt Carmel volcanics of northern Israel, associated with corundum, tistarite, anorthite, osbornite, an unnamed REE (Rare Earth Element) phase, in a Ca-Mg-Al-Si-O glass. In reflected light, carmeltazite is weakly to moderately bireflectant and weakly pleochroic from dark brown to dark green. Internal reflections are absent. Under crossed polars, the mineral is anisotropic, without characteristic rotation tints. Reflectance values for the four COM wavelengths (Rmin, Rmax (%) (λ in nm)) are: 21.8, 22.9 (471.1); 21.0, 21.6 (548.3), 19.9, 20.7 (586.6); and 18.5, 19.8 (652.3). Electron microprobe analysis (average of eight spot analyses) gave, on the basis of 11 oxygen atoms per formula unit and assuming all Ti and Sc as trivalent, the chemical formula (Ti3+3.60Al1.89Zr1.04Mg0.24Si0.13Sc0.06Ca0.05Y0.02Hf0.01)Σ=7.04O11. The simplified formula is ZrAl2Ti4O11, which requires ZrO2 24.03, Al2O3 19.88, and Ti2O3 56.09, totaling 100.00 wt %. The main diffraction lines, corresponding to multiple hkl indices, are (d in Å (relative visual intensity)): 5.04 (65), 4.09 (60), 2.961 (100), 2.885 (40), and 2.047 (60). The crystal structure study revealed carmeltazite to be orthorhombic, space group Pnma, with unit-cell parameters a = 14.0951 (9), b = 5.8123 (4), c = 10.0848 (7) Å, V = 826.2 (1) Å3, and Z = 4. The crystal structure was refined to a final R1 = 0.0216 for 1165 observed reflections with Fo > 4σ(Fo). Carmeltazite exhibits a structural arrangement similar to that observed in a defective spinel structure. The name carmeltazite derives from Mt Carmel (“CARMEL”) and from the dominant metals present in the mineral, i.e., Titanium, Aluminum and Zirconium (“TAZ”). The mineral and its name have been approved by the IMA Commission on New Minerals, Nomenclature and Classification (2018-103).

Crystal structure and temperature dependent structural phase transitions in (Ba1-xSrx)PbO3 (x = 0, 0.2, 0.6) perovskite ceramics

The structural properties of (Ba1-xSrx)PbO3 (x = 0, 0.2 and 0.6) ceramics were examined in a wide range of temperatures, from 14 K to 1223 K, using the X-ray powder diffraction method. The type of distortion of the pseudo-cubic perovskite cell was determined from the splitting of the main diffraction lines and from the analysis of the superlattice peaks. Temperature-induced structural phase transitions at high temperatures were observed. On the other hand at temperatures starting as low as 14 K, the examined ceramics did not show any phase transitions. The effect of Sr doping was evaluated and showed that with an increase in the amount of Sr2+ ions in the crystal lattice the number of SPT's decreases. Additionally, the temperatures at which these SPT's occur are shifted towards higher values. The following sequences of structural phase transitions, written using Glazer's notation, were proposed:I2/m (a-b0c-) → Ibmm (a-b0a-)→ I4/mcm (a0a0c-)→ Pm3¯m(a0a0a0) for BaPbO3I2/m (a-b0c-) → I4/mcm (a0a0c-) → Pm3¯m(a0a0a0) for (Ba0.8Sr0.2)PbO3and I2/m (a-b0c-)→ I4/mcm (a0a0c-)→ Pm3¯m(a0a0a0) for (Ba0.4Sr0.6)PbO3.These SPT's were used as trial models in refinement procedures based on the Rietveld method.

Oyonite, Ag3Mn2Pb4Sb7As4S24, a New Member of the Lillianite Homologous Series from the Uchucchacua Base-Metal Deposit, Oyon District, Peru

The new mineral species oyonite, ideally Ag3Mn2Pb4Sb7As4S24, has been discovered in the Uchucchacua base-metal deposit, Oyon district, Catajambo, Lima Department, Peru, as very rare black metallic subhedral to anhedral crystals, up to 100 μm in length, associated with orpiment, tennantite/tetrahedrite, menchettiite, and other unnamed minerals of the system Pb-Ag-Sb-Mn-As-S, in calcite matrix. Its Vickers hardness (VHN100) is 137 kg/mm2 (range 132–147). In reflected light, oyonite is weakly to moderately bireflectant and weakly pleochroic from dark grey to a dark green. Internal reflections are absent. Reflectance values for the four COM wavelengths [Rmin, Rmax (%) (λ in nm)] are: 33.9, 40.2 (471.1); 32.5, 38.9 (548.3), 31.6, 38.0 (586.6); and 29.8, 36.5 (652.3). Electron microprobe analysis gave (in wt %, average of 5 spot analyses): Cu 0.76 (2), Ag 8.39 (10), Mn 3.02 (7), Pb 24.70 (25), As 9.54 (12), Sb 28.87 (21), S 24.30 (18), total 99.58 (23). Based on 20 cations per formula unit, the chemical formula of oyonite is Cu0.38Ag2.48Mn1.75Pb3.79Sb7.55As4.05S24.12. The main diffraction lines are (d in Å, hkl and relative intensity): 3.34 (−312; 40), 3.29 (−520; 100), 2.920 (−132; 40), 2.821 (−232; 70), 2.045 (004; 50). The crystal structure study revealed oyonite to be monoclinic, space group P21/n, with unit-cell parameters a = 19.1806 (18), b = 12.7755 (14), c = 8.1789 (10) Å, β = 90.471 (11)°, V = 2004.1 (4) Å3, Z = 2. The crystal structure was refined to a final R1 = 0.032 for 6272 independent reflections. Oyonite belongs to the Sb-rich members of the andorite homeotypic sub-series within the lillianite homologous series. The name oyonite is after the Oyon district, Lima Department, Peru, the district where the type locality (Uchucchacua mine) is located.

Tiberiobardiite, Cu9Al(SiO3OH)2(OH)12(H2O)6(SO4)1.5·10H2O, a New Mineral Related to Chalcophyllite from the Cretaio Cu Prospect, Massa Marittima, Grosseto (Tuscany, Italy): Occurrence and Crystal Structure

The new mineral species tiberiobardiite, ideally Cu9Al(SiO3OH)2(OH)12(H2O)6(SO4)1.5·10H2O, has been discovered in the Cretaio Cu prospect, Massa Marittima, Grosseto, Tuscany, Italy, as very rare, light green, vitreous, tabular {0001}, pseudo-hexagonal crystals, up to 200 μm in size and 5 μm in thickness, associated with brochantite. Electron microprobe analysis gave (in wt %, average of 5 spot analyses): SO3 10.37, P2O5 3.41, As2O5 0.05, SiO2 8.13, Al2O3 5.54, Fe2O3 0.74, CuO 62.05, and ZnO 0.03, for a total of 90.32. Based on an idealized O content of 42 atoms per formula unit, assuming the presence of 16 H2O groups and 13.5 cations (without H), the empirical formula of tiberiobardiite is (Cu8.69Al0.21Fe0.10)Σ9.00Al1.00(Si1.51P0.54)Σ2.05S1.44O12.53(OH)13.47·16H2O. The main diffraction lines, corresponding to multiple hkl indices, are [d in Å (relative visual intensity)]: 9.4 (s), 4.67 (s), 2.576 (m), 2.330 (m), and 2.041 (mw). The crystal structure study revealed tiberiobardiite to be trigonal, space group R 3 ¯ , with unit-cell parameters a = 10.6860(4), c = 28.3239(10) Å, V = 2801.0(2) Å3, and Z = 3. The crystal structure was refined to a final R1 = 0.060 for 1747 reflections with Fo > 4σ (Fo) and 99 refined parameters. Tiberiobardiite is the Si-analogue of chalcophyllite, with Si4+ replacing As5+ through the coupled substitution As5+ + O2− = Si4+ + (OH)−. The name tiberiobardiite honors Tiberio Bardi (b. 1960) for his contribution to the study of the mineralogy of Tuscany.

Influence of film thickness on the structural transition cubic/hexagonal within Ti0.38Al0.62N films

Metastable Ti1−xAlxN films have the more outstanding functional properties in the range of composition around x = 0.6 for their use as protective coatings. They exhibit complex texture because of the phase transition between TiN-like rocksalt and AlN-like wurtzite structures. The competitive growth between cubic and wurtzite domains is studied in metastable Ti0.38Al0.62N thin film deposited by reactive magnetron sputtering for thicknesses between 1 and 3.7 μm. Long-range order is analysed within the film by X-ray diffraction and cross-sectional TEM imaging. The study is complemented by using Ti K-edge diffraction anomalous spectroscopy to obtain differentiated information on short-range order around Ti atoms incorporated in cubic and wurtzite domains. The growth along the [111]c direction has the effect of promoting the appearance of crystallites with wurtzite symmetry oriented along [001]h. In the middle of the layer, cubic and wurtzite domains become coherently oriented. Lattice distortions, which affect long- and short-range order, are revealed by the anisotropy of broadening of the diffraction lines and by spectroscopic data collected on the main diffraction lines. The fine pre-edge structure indicates a strong distortion of the tetrahedral sites occupied by Ti atoms along the c axis, which minimizes the in-plane lattice mismatch. Near the film surface, a dramatic change in growth directions is observed. A better understanding of the structural transition mechanism in the (Ti,Al)N system could help improve the mechanical performances of these coatings in the future.

Role of defectivity on the crystallography of martensitic transformations in Ti50Ni40Cu10: an XRD investigation

Abstract Martensitic transformations in Ni50Ti40Cu10 are well known to proceed with a two-step process, from B2 austenite to monoclinic B19′ with intermediate orthorhombic B19. These transformations can be readily followed by X-ray diffraction especially in solution heat-treated materials through split and distribution of the main diffraction lines, while peaks broadening and overlap make the transformations more difficult to be described in highly defective materials. The present study addresses the effect of defects and chemical inhomogeneities on the martensitic transformation, placing particular emphasis on the crystallography of the low temperature B19 to B19′ phase transition. Lattice strains proved to be a powerful tool to monitor the martensitic transformations: whereas a clear discontinuity is observed for the solution heat-treated sample, defects promote a continuous progressive distortion from B19 to B19′. Calorimetry and internal friction investigations were added as a reference to verify the occurrence of the transformations and define the corresponding temperatures.

Lead-antimony sulfosalts from Tuscany (Italy). XXI. Bernarlottiite, Pb12 (As10 Sb6) Σ16 S36, a new N = 3.5 member of the sartorite homologous series from the Ceragiola marble quarry: occurrence and crystal structure

The new mineral species bernarlottiite, Pb 12 (As 10 Sb 6 ) Σ16 S 36 , has been discovered in cavities of the Early Jurassic marbles from the Ceragiola quarry, Seravezza, Apuan Alps, Tuscany, Italy. Its name honours Bernardino Lotti (1847–1933) for his significant contribution to the knowledge of the geology of Tuscany and to the development of the Tuscan mining industry. It occurs as lead-grey acicular crystals up to 1 mm in length and few μm in width, with a metallic lustre, associated with Sb-rich sartorite. Under the ore microscope, bernarlottiite is white with abundant red internal reflections; pleochroism is weak in air, with shades of grey-blue. Anisotropism is distinct to strong, with greyish-bluish rotation tints. Reflectance percentages for the four COM wavelengths are [ R min , R max (%), (λ)]: 30.0, 37.5 (470 nm); 30.3, 37.3 (546 nm); 29.7, 36.8 (589 nm); and 29.3, 36.2 (650 nm). Electron-microprobe analyses, collected on two different grains, give (in wt%): Cu 0.09 (16), Pb 48.89 (1.26), As 17.48 (22), Sb 11.36 (10), S 23.11 (32), total 100.93 (1.38) (sample # 2987) and Pb 47.43 (26), As 14.56 (24), Sb 13.92 (18), S 22.64 (17), total 98.56 (44) (sample # 3819). On the basis of ΣMe = 28 atoms per formula unit, the chemical formulae are Cu 0.07(12) Pb 11.71 (18)As 11.59(21) Sb 4.63(9) S 35.78(48) and Pb 11.92(6) As 10.12(14) Sb 5.95(8) S 36.76(32) for samples # 2987 and # 3819, respectively. The main diffraction lines, corresponding to multiple h k l indices, are [ d in A (relative visual intensity)]: 3.851 (s), 3.794 (s), 3.278 (s), 3.075 (s), 2.748 (vs), 2.363 (s), and 2.221 (vs). The crystal structure study gives a triclinic unit cell, space group P 1 ¯ , with a = 23.704 (8), b = 8.386 (2), c = 23.501 (8) A, α = 89.91 (1), β = 102.93 (1), γ = 89.88 (1), V = 4553 (2) A 3 , Z = 3. The crystal structure has been solved and refined to R 1 = 0.088 on the basis of 7317 reflections with F o >4σ ( F o ). Bernarlottiite is a new N = 3.5 homeotype of the sartorite homologous series, with a 3 a superstructure relative to that of baumhauerite. Its crystal structure can be described as being formed by 1:1 alternation of sartorite-type ( N = 3) and dufrenoysite-type ( N = 4) layers along c, connected by Pb atoms with tricapped trigonal prismatic coordination. Each layer results from the stacking of two types of ribbons along a, a centrosymmetric one alternating with two acentric ones. The three main building operators of the structure are (1) the interlayers As- versus -Pb crossed substitution, stabilizing the combined N = (3, 4) baumhauerite homologue, (2) the inter-ribbon Sb partitioning in the sartorite-type layer, with “symmetrization” of the Sb-rich ribbon, that induces the 3 a superstructure, and (3) the common (As, Sb) polymerization through short (As,Sb)–S bonds.

Richardsollyite, TlPbAsS3, a new sulfosalt from the Lengenbach quarry, Binn Valley, Switzerland

The new mineral species richardsollyite, TlPbAsS 3 , was discovered in the Lengenbach quarry, Imfeld, Binn Valley, Canton Valais, Switzerland, intimately associated with hutchinsonite and baryte. It occurs as grey-black crystals, up to 750 μm, with a metallic lustre. Under the reflected-light microscope, richardsollyite is grey, with bright-red internal reflections; anisotropy is distinct, with greyish-white to bluish rotation tints. Reflectance values for the four COM wavelengths are [ R min , R max (%), (λ)]: 27.9, 29.8 (471.1 nm); 27.8, 31.0 (548.3 nm); 27.3, 30.8 (586.6 nm); and 27.0, 30.5 (652.3 nm). Electron microprobe analysis gave (in wt%): Tl 34.72(51), Pb 35.45(20), As 12.80(14), Sb 0.04(1), S 16.22(13), total 99.24(47). On the basis of 6 atoms per formula unit, the chemical formula is Tl 1.001 Pb 1.008 (As 1.007 Sb 0.002 ) Σ1.009 S 2.982 . The main diffraction lines [ d in A (intensity) hkl ] are: 4.23 (80) 1 ¯ 0 2 ; 3.875 (70) 2 ¯ 1 1 ; 3.762 (100) 2 1 0, 1 2 0; 3.278 (70) 1 0 2; 2.931 (70) 0 2 2; 2.714 (70) 1 ¯ 1 3 ; and 2.622 (80) 3 ¯ 1 2 . Richardsollyite is monoclinic, space group P 2 1 / c , with a = 8.8925(2), b = 8.4154(2), c = 8.5754(2) A, β = 108.665(3)°, V = 607.98(3) A 3 , Z = 4. The crystal structure was solved and refined to R 1 = 0.0242 on the basis of 1590 reflections with F o > 4σ( F o ). It can be described as formed by (1 0 0) [Pb (AsS 3 )] − layers sandwiching Tl + cations, and is isostructural with synthetic ABCX 3 ( A = K, Rb, Cs; B = Eu, Ba; C = As, Sb; X = S, Se) compounds. The new mineral is named after Richard Harrison Solly (1851–1925) for his outstanding contribution to the knowledge of the Lengenbach mineralogy during the first flourishing period of Lengenbach investigations, at the beginning of the 20th Century.

Cabvinite, Th2F7(OH)·3H2O, the first natural actinide halide

The new mineral species cabvinite, Th 2 F 7 (OH)·3H 2 O (IMA 2016-011), has been discovered in the Mo-Bi ore deposit of Su Seinargiu, Sarroch, Cagliari, Sardinia, Italy. It occurs as white square prismatic crystals, up to 100 μm in length and 40 μm in thickness, associated with brookite and iron oxy-hydroxides in vugs of quartz veins. Electron microprobe analysis gave (mean of five spot analyses, in wt%): ThO 2 82.35, F 19.93, H 2 O calc 10.21, sum 112.49, O=F −8.40, total 104.09. On the basis of 2 Th atoms per formula unit, the empirical formula of cabvinite is Th 2 F 6.7 (OH) 1.3 ·3H 2 O. Main diffraction lines in the X-ray powder diffraction pattern are [ d (A) (relative visual intensity) hkl ]: 8.02 (ms) 110; 3.975 (s) 121,211; 3.595 (m) 310,130; 2.832 (m) 400,321,231; 2.125 (m) 402; 2.056 (m) 332; and 2.004 (ms) 440,521,251. Cabvinite is tetragonal, space group I 4/ m , with a = 11.3689(2), c = 6.4175(1) A, V = 829.47(2) A 3 , Z = 4. The crystal structure has been solved and refined to R 1 = 0.021 on the basis of 813 reflections with F o > 4σ( F o ). It consists of Th tricapped trigonal prisms, connected through corner-sharing, giving rise to a framework hosting [001] tunnels. Cabvinite is the first natural actinide halide, and the site of discovery appears to provide a natural laboratory for the study of Th mobility and sequestration.

Tetragonal Almandine-Pyrope Phase, TAPP: finally a name for it, the new mineral jeffbenite

AbstractJeffbenite, ideally Mg3Al2Si3O8, previously known as tetragonal-almandine-pyrope-phase ('TAPP’), has been characterized as a new mineral from an inclusion in an alluvial diamond from São Luiz river, Juina district of Mato Grosso, Brazil. Its density is 3.576 g/cm3 and its microhardness is ∼7. Jeffbenite is uniaxial (-) with refractive indexes ω = 1.733(5) and ε = 1.721 (5). The crystals are in general transparent emerald green.Its approximate chemical formula is (Mg262Fe2+0.27)(Al186Cr016)(Si2 g2Al018)O12 with very minor amounts of Mn, Na and Ca. Laser ablation ICP-MS showed that jeffbenite has a very low concentration of trace elements. Jeffbenite is tetragonal with space group I42d, cell edges being a = 6.5231(1) and c = 18.1756(3) Å. The main diffraction lines of the powder diagram are [d (in Å), intensity, hkl]: 2.647, 100, 2 0 4; 1.625, 44, 3 2 5; 2.881, 24, 2 1 1; 2.220, 19, 2 0 6; 1.390, 13, 4 2 4; 3.069, 11,2 0 2; 2.056, 11,2 2 4; 1.372, 11,2 0 12.The structural formula of jeffbenite can be written as (M1)(M2)2(M3)2(T1)(T2)2O12 with M1 dominated by Mg, M2 dominated by Al, M3 dominated again by Mg and both T1 and T2 almost fully occupied by Si. The two tetrahedra do not share any oxygen with each other (i.e. jeffbenite is classified as an orthosilicate).Jeffbenite was approved as a new mineral by the IMA Commission on New Minerals and Mineral Names with the code IMA 2014-097. Its name is after Jeffrey W. Harris and Ben Harte, two world-leading scientists in diamond research. The petrological importance of jeffbenite is related to its very deep origin, which may allow its use as a pressure marker for detecting super-deep diamonds. Previous experimental work carried out on a Ti-rich jeffbenite establishes that it can be formed at 13 GPa and 1700 K as maximum P-T conditions.

Lead-antimony sulfosalts from Tuscany (Italy). XVII. Meerschautite, (Ag,Cu)5.5Pb42.4(Sb,As)45.1S112O0.8, a new expanded derivative of owyheeite from the Pollone mine, Valdicastello Carducci: occurrence and crystal structure

AbstractThe new mineral species meerschautite, ideally (Ag,Cu)5.5Pb42.4(Sb,As)45.1S112O0.8, has been discovered in the baryte + pyrite ± (Pb-Zn-Ag) deposit of the Pollone mine, near Valdicastello Carducci, Apuan Alps, Tuscany, Italy. It occurs as black prismatic crystals, striated along [100], up to 2 mm long and 0.5 mm thick, associated with baryte, boulangerite, pyrite, quartz and sphalerite. Meerschautite is opaque with a metallic lustre and shows a black streak. In reflected light, meerschautite is white in colour, weakly bireflectant and non pleochroic. With crossed polars, it is distinctly anisotropic with grey to dark grey rotation tints with brownish and greenish shades. Reflectance percentages for COM wavelengths [λ (nm), Rair (%)] are: 470: 39.7/41.4; 546: 38.3/39.9; 589: 37.4/39.0; 650: 35.8/37.2. Electron-microprobe data collected on two different samples gave (wt.%): Cu 0.22, Ag 3.15, Tl 0.07, Pb 48.54, Sb 25.41, As 2.82, S 19.74, Se 0.14, Cl 0.03, sum 100.12 (# 1) and Cu 0.22, Ag 3.04, Tl 0.13, Pb 48.53, Sb 25.40, As 2.93, Bi 0.06, S 19.82, Se 0.13, Cl 0.05, sum 100.31 (# 2). On the basis of 112 anions (S+Se+Cl) per formula unit, the empirical formulae are (Ag5.29Cu0.63)∑5.92(Pb42.43Tl0.06)∑42.49(Sb37.80As6.82)∑44.62(S111.53Se0.32Cl0.15)∑112 (# 1) and (Ag5.08Cu0.62)∑5.70(Pb42.22Tl0.12)∑42.34(Sb37.61As7.07Bi0.05)∑44.73(S111.45Se0.30Cl0.25)∑112 (# 2). Main diffraction lines, corresponding to multiple hkl indices, are [d in Å (relative visual intensity)]: 3.762 (m), 3.663 (s), 3.334 (vs), 3.244 (s), 3.016 (m), 2.968 (m), 2.902 (m), 2.072 (ms). The crystal structure study gave a monoclinic unit cell, space group P21, with a = 8.2393(1), b = 43.6015(13), c = 28.3688(8) Å, β = 94.128(2)°, V = 10164.93(2) Å3, Z = 2. The crystal structure has been solved and refined to a final R1 = 0.122 on the basis of 49,037 observed reflections. The structure is based on two building blocks, both formed by a complex column with a pseudotrigonal Pb6S12 core and two arms of unequal lengths (short and long arms, respectively). Two different kinds of short arms occur in meerschautite. One is an Ag-rich arm, whereas the other shows localized Sb–O–Sb bonds. Meerschautite is an expanded derivative of owyheeite and has quasi-homeotypic relationships with sterryite and parasterryite.

Ciriottiite, Cu(Cu,Ag)3Pb19(Sb,As)22(As2)S56, the Cu-Analogue of Sterryite from the Tavagnasco Mining District, Piedmont, Italy

The new mineral species ciriottiite, ideally Cu(Cu,Ag)3Pb19(Sb,As)22(As2)S56 has been discovered in the Tavagnasco mining district, Piedmont, Italy, as very rare black metallic tubular crystals, up to 150 μm in length, associated with Bi sulfosalts and arsenopyrite. Its Vickers hardness (VHN10) is 203 kg/mm2 (range 190–219). In reflected light, ciriottiite is light grey in color, distinctly anisotropic with brownish to greenish rotation tints. Internal reflections are absent. Reflectance values for the four COM wavelengths (Rmin, Rmax (%) (λ in nm)) are: 33.2, 37.8 (471.1); 31.8, 35.3 (548.3), 31.0, 34.7 (586.6); and 27.9, 32.5 (652.3). Electron microprobe analysis gave (in wt %, average of 5 spot analyses): Cu 2.33 (8), Ag 0.53 (5), Hg 0.98 (6), Tl 0.78 (3), Pb 44.06 (14), As 4.66 (7), Sb 23.90 (10), Bi 1.75 (7), total 99.38 (26). On the basis of 56 S atoms per formula unit, the chemical formula of ciriottiite is Cu3.23(11)Ag0.43(4)Hg0.43(2)Pb18.74(9)Tl0.34(1)Sb17.30(5)As5.48(10)Bi0.74(3)S56. The main diffraction lines, corresponding to multiple hkl indices, are (d in Å (relative visual intensity)): 4.09 (m), 3.91 (m), 3.63 (vs), 3.57 (m), 3.22 (m), 2.80 (mw), 2.07 (s). The crystal structure study revealed ciriottiite to be monoclinic, space group P21/n, with unit-cell parameters a = 8.178 (2), b = 28.223 (6), c = 42.452 (5) Å, β = 93.55 (2)°, V = 9779.5 (5) Å3, Z = 4. The crystal structure was refined to a final R1 = 0.118 for 21304 observed reflections. Ciriottiite is the Cu analogue of sterryite and can be described as an expanded derivative of owyheeite. The name ciriottiite honors Marco Ernesto Ciriotti (b. 1945) for his longstanding contribution to mineral systematics.

Ferrostalderite, CuFe2TlAs2S6, a new mineral from Lengenbach, Switzerland: occurrence, crystal structure, and emphasis on the role of iron in sulfosalts

AbstractThe new mineral species ferrostalderite, CuFe2TlAs2S6, was discovered in the Lengenbach quarry, Binn Valley, Wallis, Switzerland. It occurs as minute, metallic, black, equant to prismatic crystals, up to 50 mu;m, associated with dolomite, realgar, baumhauerite (?) and pyrite. Minimum and maximum reflectance data for COM wavelengths in air are [λ (nm): R (%)]: 471.1: 24.2/25.4; 548.3: 23.7/24.7; 586.6: 22.9/23.8; 652.3: 21.0/22.0. Electron microprobe analyses give (wt.%): Cu 6.24(25), Ag 4.18(9), Fe 9.95(83), Zn 4.46(91), Hg 1.22(26), Tl 26.86(62), As 19.05(18), Sb 0.63(6),S 25.39(47), total 97.98(72). On the basis of 12 atoms per formula unit, the chemical formula of ferrostalderite is Cu0.75(2)Ag0.30(1)Fe1.36(10)Zn0.52(11)Hg0.05(1)Tl1.00(1)[As1.94(4)Sb0.04(1)]∑1.98(4)S6.04(4). The new mineral is tetragonal, space group I4̄2 m, with a = 9.8786(5), c = 10.8489(8) Å, V = 1058.71(11) Å3, Z = 4. The main diffraction lines of the calculated powder diagram are [d (in Å), intensity, hkl]: 4.092, 70, 211; 3.493, 23, 220; 3.396, 35, 103; 3.124, 17, 310; 2.937, 100, 222; 2.656, 19, 321; 2.470, 19, 400; 2.435, 33, 303. The crystal structure of ferrostalderite has been refined by Xray single-crystal data to a final R1= 0.050, on the basis of 1169 reflections with F0 > 4σ(F0). It shows a three dimensional framework of (Cu,Fe)-centred tetrahedra (1M1 + 2 M2), with channels parallel to [001] hosting disymmetric TlS6and (As,Sb)S3 polyhedra. Ferrostalderite is derived from its isotype stalderiteM1CuM2Zn2TlAs2S6through the homovalent substitution M2Zn2+ → M2Fe2+. The ideal crystal-chemical formula of ferrostalderite isM1CuM2Fe2TlAs2S6.

Ralphcannonite, AgZn2TlAs2S6, a new mineral of the routhierite isotypic series from Lengenbach, Binn Valley, Switzerland

AbstractThe new mineral species ralphcannonite, AgZn2TlAs2S6, was discovered in the Lengenbach quarry, Binn Valley, Wallis, Switzerland. It occurs as metallic black equant, isometric to prismatic crystals, up to 50 μm, associated with dufrénoysite, hatchite, realgar and baryte. Minimum and maximum reflectance data for COM wavelengths in air are [λ (nm): R (%)]: 471.1: 25.8/27.1; 548.3: 25.2/26.6; 586.6: 24.6/25.8; 652.3: 23.9/24.8. Electron microprobe analyses give (wt.%): Cu 2.01(6), Ag 8.50(16), Zn 10.94(20), Fe 3.25(8), Hg 7.92(12), Tl 24.58(26), As 18.36(19), Sb 0.17(4), S 24.03(21), total 99.76(71). On the basis of 12 atoms per formula unit, the chemical formula of ralphcannonite is Ag0.63(2)Cu0.25(2)Zn1.35(5)Fe0.47(1)Hg0.32(2)Tl0.97(3)[As1.97(6)Sb0.01(1)]Σ1.98(5)S6.03(8). The new mineral is tetragonal, space group I42m, with a = 9.861 (2), c = 11.125(3) Å, V = 1081.8(4) Å3, Z = 4. The main diffraction lines of the calculated powder diagram are [d (in Å), intensity, hkl]: 4.100, 85, 211; 3.471, 40, 103; 2.954, 100, 222; 2.465, 24, 400; 2.460, 39, 303. The crystal structure of ralphcannonite has been refined by X-ray single-crystal data to a final R1 = 0.030, on the basis of 140 observed reflections [Fo > 4σ(Fo)]. It shows a three dimensional framework of (Ag,Zn)-centred tetrahedra (1 M1 + 2 M2), with channels parallel to [001] hosting TlS6 and (As,Sb)S3 disymmetric polyhedra. Ralphcannonite is derived from its isotype routhierite M1CuM2Hg2TlAs2S6 through the double heterovalent substitution M1Cu+ + M2Hg2+ → M1Zn2+ + M2Ag+. This substitution obeys a steric constraint, with Ag+, the largest cation relative to Zn2+ and Cu+, entering the largest M2 site, as observed in arsiccioite. The ideal crystal-chemical formula of ralphcannonite is M1ZnM2(Zn0.5Ag0.5)2TlAs2S6.

Suseinargiuite, (Na0.5Bi0.5)MoO4, the Na-Bi analogue of wulfenite, from Su Seinargiu, Sardinia, Italy

The new mineral species suseinargiuite, (Na 0.5 Bi 0.5 )MoO 4 , has been discovered in the Mo-Bi occurrence of Su Seinargiu, Sarroch, Cagliari, Sardinia, Italy. It occurs as hemispherical aggregates of very small acicular crystals, up to some micrometres in length. It is colourless, with a pearly to adamantine lustre. In the studied specimens, suseinargiuite is associated with wulfenite. Micro-Raman spectra were collected in the region between 100 and 2000 cm −1 . The following bands have been observed (in cm −1 ): 131, 188, 319, ~ 376, ~ 772, and 876. Electron microprobe data collected on a chemically zoned grain gave (outer and inner zone, respectively – in wt%): MoO 3 49.03, Bi 2 O 3 42.97, PbO 2.89, Na 2 O 3.69, total 98.58, and MoO 3 45.59, Bi 2 O 3 34.47, PbO 12.04, Na 2 O 3.03, total 95.13. On the basis of 4 O atoms per formula unit, the chemical formulae are (Na 0.35 Bi 0.54 Pb 0.04 ) Σ=0.93 Mo 0.99 O 4 and (Na 0.31 Bi 0.46 Pb 0.17 ) Σ=0.94 Mo 0.99 O 4 , respectively. Main diffraction lines are [ d in A (relative intensity) hkl ]: 3.146 (100) 112, 2.912 (13) 004, 2.652 (18) 200, 1.964 (34) 204, 1.875 (15) 220, 1.728 (19) 116, and 1.616 (28) 312 and 132. Unit-cell parameters, refined from the powder X-ray diffraction data in a tetragonal setting, space group I 4 1 / a , are a = 5.296(1), c = 11.673(2) A, V = 327.4(1) A 3 , Z = 4. Owing to the lack of suitable crystals and the very small amount of available material, the crystal structure of suseinargiuite was not solved. However, X-ray powder diffraction data, micro-Raman spectra, as well as chemical analysis, show the close correspondence between suseinargiuite with synthetic (Na 0.5 Bi 0.5 )MoO 4 , which displays a scheelite-type structure.

Nuragheite, Th(MoO4)2{middle dot}H2O, the second natural thorium molybdate and its relationships to ichnusaite and synthetic Th(MoO4)2

The new mineral species nuragheite, Th(MoO 4 ) 2 ·H 2 O, has been discovered in the Mo-Bi mineralization of Su Seinargiu, Sarroch, Cagliari, Sardinia, Italy. It occurs as colorless thin {100} tabular crystals, up to 200 μm in length, associated with muscovite, xenotime-(Y), and ichnusaite, Th(MoO 4 ) 2 ·3H 2 O. Luster is pearly to adamantine; nuragheite is brittle, with a perfect (100) cleavage. Owing to the very small amount of available material and its intimate association with ichnusaite, density and optical properties were not measured. Electron microprobe analysis gave (wt% = mean of six spot analyses): MoO 3 49.38, ThO 2 45.39, H 2 Ocalc 3.09, total 97.86. On the basis of eight O atoms per formula unit and assuming one H 2 O group, in agreement with the crystal structure data, the chemical formula of nuragheite is Th 1.00 Mo 2.00 O 8 ·H 2 O. Main diffraction lines, corresponding to multiple hkl indices, are [d in Å (relative visual intensity)]: 5.28 (m), 5.20 (m), 5.04 (m), 4.756 (m), 3.688 (m), 3.546 (vs), 3.177 (s), 3.024 (m). The crystal structure study gives a monoclinic unit cell, space group P2 1 /c, with a = 7.358(2), b = 10.544(3), c = 9.489(2) Å, β = 91.88(2)°, V = 735.8(2) Å 3 , Z = 4. The crystal structure has been solved and refined to a final R 1 = 0.078 on the basis of 1342 “observed” reflections [Fo > 4σ(F o )]. It consists of (100) layers formed by ninefold-coordinated Th-centered polyhedra and Mo-centered tetrahedra. Its crystal structure is discussed in relation to that of ichnusaite and that of synthetic orthorhombic Th(MoO 4 ) 2 . The relationship between the progressive loss of water in the interlayer and the layer topology passing from ichnusaite through nuragheite to synthetic (ThMoO 4 ) 2 is examined. Nuragheite, the second thorium molybdate reported so far in nature, adds new data to the understanding of the crystal chemistry of actinide molybdates potentially forming during the alteration of spent nuclear fuel and influencing the release of radionuclides under repository conditions.