Metallic Luster Research Articles

Ferrofettelite, [Ag6As2S7][Ag10FeAs2S8], a new sulfosalt from the Glasberg quarry, Odenwald, Germany

AbstractFerrofettelite, 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.

Guite, the spinel-structured Co2+Co3+2O4, a new mineral from the Sicomines copper–cobalt mine, Democratic Republic of Congo

AbstractGuite (IMA2017-080), Co3O4, is a new mineral species and an important economic mineral found in the Sicomines copper-cobalt mine, located ~11 km southwest of Kolwezi City, Democratic Republic of Congo. The mineral occurs as a granular agglomerate, 50 to 500 μm in size, and is associated closely with heterogenite in a quartz matrix. Guite is opaque, has a dark grey colour with metallic lustre and a black streak. In reflected light microscopy, it is white with no internal reflections. The reflectance values (in air,Rin %) are: 27.0 (470 nm); 25.6 (546 nm); 25.2 (589 nm), and 24.6 (650 nm). The average of 20 electron-microprobe analyses is Co 71.53, Cu 0.58, Mn 0.67, Si 0.25, O 26.78, total 99.82 wt.%, corresponding to the empirical formula calculated on the basis of 4 O apfu: (Co2+0.92Cu2+0.02Si4+0.02)Σ0.96(Co3+1.98Mn3+0.03)Σ2.01O4.00, with Co2+and Co3+partitioned using charge balance. The ideal formula is Co2+Co3+2O4. Guite is cubic with space groupFd$\bar{3}$m. The unit cell parameters refined from the single crystal X-ray diffraction data are:a= 8.0898(1) Å,V= 529.436(11) Å3andZ= 8. The calculated density of guite is 6.003 g/cm3. The eight strongest observed powder X-ray diffraction lines [din Å (I/I0) (hkl)] are: 4.6714 (16.7) (111), 2.8620 (18.4) (220), 2.4399 (100) (311), 2.3348 (10.4) (222), 2.0230 (24.8) (400), 1.5556 (26.3) (511, 333), 1.4296 (37.7) (440) and 1.0524 (10.1) (731, 553). The crystal structure of guite was determined by single-crystal X-ray diffraction and refined toR= 0.0132 for 3748 (69 unique) reflections. Guite has a typical spinel-type structure with Co2+in tetrahedral coordination with a Co2+–O bonding length of 1.941(1) Å, and Co3+in octahedral coordination with a Co3+–O bonding length of 1.919(1) Å. The structure is composed of cross-linked framework of chains of Co3+–O6octahedra sharing the equilateral triangle edges (2.550 Å) in three directions [0 1 1], [1 1 0], [1 0 1] with Co2+filling the tetrahedral interstices among the chains. Guite is named in honour of Prof. Xiangping Gu (1964–).

Argentotetrahedrite-(Zn), Ag6(Cu4Zn2)Sb4S13, a new member of the tetrahedrite group

AbstractArgentotetrahedrite-(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.

Impact of Lithium‐Ion Coordination on Lithium Electrodeposition

The lithium dendrite and parasitic reactions are two major challenges for lithium (Li) metal anode—the most promising anode materials for high‐energy‐density batteries. In this work, both the dendrite and parasitic reactions that occurred between the liquid electrolyte and Li‐metal anode could be largely inhibited by regulating the Li+‐solvation structure. The saturated Li+‐solvation species exist in commonly used LiPF6 liquid electrolyte that needs extra energy to desolvation during Li‐electrodeposition. Partial solvation induced high‐energy state Li‐ions would be more energy favorable during the electron‐reduction process, dominating the competition with solvent reduction reactions. The Li‐symmetric cells that are cycling at higher temperatures show better performance; the cycled lithium metal anode with metallic lustre and the dendrite‐free surface is observed. Theoretical calculation and experimental measurements reveal the existence of high‐energy state Li+‐solvates species, and their concentration increases with temperature. This study provides insight into the Li+‐solvation structure and its electrodeposition characteristics.

Suppressing electrolyte-lithium metal reactivity via Li+-desolvation in uniform nano-porous separator

Lithium reactivity with electrolytes leads to their continuous consumption and dendrite growth, which constitute major obstacles to harnessing the tremendous energy of lithium-metal anode in a reversible manner. Considerable attention has been focused on inhibiting dendrite via interface and electrolyte engineering, while admitting electrolyte-lithium metal reactivity as a thermodynamic inevitability. Here, we report the effective suppression of such reactivity through a nano-porous separator. Calculation assisted by diversified characterizations reveals that the separator partially desolvates Li+ in confinement created by its uniform nanopores, and deactivates solvents for electrochemical reduction before Li0-deposition occurs. The consequence of such deactivation is realizing dendrite-free lithium-metal electrode, which even retaining its metallic lustre after long-term cycling in both Li-symmetric cell and high-voltage Li-metal battery with LiNi0.6Mn0.2Co0.2O2 as cathode. The discovery that a nano-structured separator alters both bulk and interfacial behaviors of electrolytes points us toward a new direction to harness lithium-metal as the most promising anode.

Deposition of metallic silver from versatile amidinate precursors for use in functional materials

Silver (Ag) amidinate metal organic decomposition precursors of the type: [Ag2((ArN)2C(H))2] (Ar = 2,6-dimethylphenyl (1), 2,6-diethylphenyl (2) and 2,6-diisopropylphenyl (3)) have been used for the first time in the deposition of Ag films on glass with multiple functionalities with potential application in optical/biological sensors or for use in electronic circuitry. Precursors 1–3 were isolated from the reaction of silver acetate with the appropriate ligand in a 1:2 stoichiometry and were characterized by 1H and 13C{1H} NMR, thermal gravimetric analysis and single crystal X-ray diffraction for 2. Single-layer depositions at 200 °C on glass substrates via spin coating produced transparent (>90% transmittance) coatings, with well-defined Ag nanoparticles. Multi-layer depositions at 200 °C on glass had a metallic lustre and were found to be conductive ( ρ = 0.916–1.83 × 10−6 Ωm). All films were strongly adhered and displayed excellent coverage of the substrate. Ag films deposited from 1 to 3 were analysed by grazing incidence X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive X-ray analysis and scanning electron microscopy, with optical properties determined by UV-Vis spectroscopy.

Immersion pickling of oxide layer on hot-rolled 2205 duplex stainless steel in sulfuric acid with different additives

The oxide layer formed after hot-rolling of duplex stainless steel (DSS) alloy 2205 was studied by electron probe microanalysis (EPMA) with wavelength dispersive spectrometry (WDS). Immersion pickling of the oxide layer on hot-rolled 2205 DSS in sulfuric acid at 80 °C with different additives was investigated via open-circuit potential and SEM imaging. The effects of different pickling solutions on descaling capacity were discussed. Results showed that the outer layer of the oxide layer was mainly iron oxide, whereas the maximum concentration of oxidized Cr occurred inside the layer; oxidized Cr extended far beyond the oxide/metal interface. The removal capacity of the oxide layer was weak with a sulfuric acid solution of 300 g/L. Many surface oxides appeared after the 20 min immersion test. After adding 1 mol/L NaCl, the pickling effect was significantly improved, and the open-circuit potential reduced from 0.3V to –0.32V. However, after a 20-min substrate immersion test, the surface was rough. Continuous addition of 50 g/L hexamethylenetetramine could remove the oxide in 20 min, resulting in a surface with a metallic luster. The initial potential of the reaction was –0.325 V. The potential then rose rapidly to –0.312 V within 280 s. The rapid increase in potential could be attributed to the inhibitory effect of hexamethylenetetramine. The optimum pickling process was as follows: 300 g/L H2SO4 + 1 mol/L NaCl+ 50 g/L hexamethylenetetramine solution at 80 °C in 20 min.

THE RESTORATION OF KUFIC DIRHAMS IN THE LIGHT OF MODERN STUDIES

The article examines the restoration of Kufic dirhams from the collection of the National Museum of the History of Ukraine; it presents the interrelationship of chemical-physical, aesthetic and restorationethical components of identical exhibits and also structures the main formations of silver and copper according to their influence on the condition of the object. The problems of the background for further restoration measures of destructive processes of archaeological exhibits made of silver-based alloy are considered, and the nature of the aesthetic component of silver exhibits is outlined. Based on the analysis of modern methods of restoration of similar exhibits, the current limits of the range of approaches to solving similar problems are outlined. As a result of the study of exhibits – Kufic dirhams, ways of developing restoration methods of patination at museum restoration are revealed. The proper display appearance and, accordingly, the nature and depth of restoration treatments significantly differ all over the world. The above-mentioned issues are especially acute in the restoration of silver due to the significant contrast in the appearance of exhibits of different degrees of preservation. As a result of mineralization, the shape of the silver object is usually deformed, and the surface loses its metallic luster. It is difficult to distinguish exhibits with a significant copper content from copper ones by their appearance. The restoration approaches and conservation measures have significant differences, so they require a careful study. This study examines the processes of preliminary removal of persistent wax layering, a restoration measure rarely analyzed by researchers. Highlighting the restoration of Kufic dirhams from the collection of the National Museum of the History of Ukraine has a particular interest in working with similar exhibits and substantiating the prospects for the direction of further research.

Effects of duty cycle on microstructure and iodine-induced stress corrosion cracking behavior of pulse electro-deposited zirconium coating

ABSTRACT Compact and dense zirconium coatings with silvery-white metallic luster were deposited on the surfaces of alloy ZIRLO under different duty cycles of 20%, 50% and 80% by pulse electro-deposition (PED) method in FLiNaK molten salt at 1023 K. The characteristics of the Zr coatings were investigated by SEM, EDS and XRD. The iodine-induced stress corrosion cracking(I-SCC) behavior of the Zr-coated alloy ZIRLO was investigated using slow strain rate tensile (SSRT) tests. The results showed that as the duty cycle increased from 20% to 80%, the average grain size of zirconium deposits increased but current efficiency decreased progressively. All of the Zr-coated samples improve the ultimate tensile strength and ductility in iodized butanol solution with respect to the uncoated Zr. The sample with Zr coating of 50% duty cycle has the highest ultimate tensile strength and ductility during the SSRT test in iodized butanol solution.

The Different Inclusions’ Characteristics between Natural and Heat-Treated Tanzanite: Evidence from Raman Spectroscopy

In this paper, Raman spectroscopy experiments were used to distinguish the characteristics of inclusions (calcite, anatase, graphite etc.) between natural and heat-treated tanzanite. These characteristics were preliminarily divided according to their pleochroism. In natural unheated tanzanite (N5), calcite inclusion is often interspersed with dolomite and has Raman shifts around 156, 283, 710, and 1087 cm−1. In other high temperature treatment samples, the baseline of calcite increased and their Raman peaks gradually shifted towards lower frequencies. Anatase inclusions in natural tanzanite (N5) have four characteristic Raman peaks around 146, 394, 514, and 641 cm−1. Because of the longer Ti-O bond and the wider bond angle distribution caused by high temperature, fewer Raman peaks were observed and the peaks’ intensities were weakened in the heat-treated T7 sample. The black graphite inclusions are often scattered or have a dotted distribution. The most obvious difference between natural and heat-treated samples is that the latter lack the characteristic 1350 cm−1 Raman peak of graphite, thus representing the order and structural incompleteness of graphite. In addition, there are other inclusions in natural unheated tanzanite, such as lead-grey molybdenite with strong metallic luster, randomly scattered prehnite with white dots, orange-yellow rounded rutile, and metallic luster hematite.

The effects of the metal pigment, adsorbent, extractant and their feeding methods on the properties of polycarbonate/acrylonitrile–butadiene–styrene composites

The aim of the present work is to upgrade the functionality and applicability of polycarbonate (PC)/acrylonitrile–butadiene–styrene (ABS) blends by means of a blending technique. Metallic glossy PC/ABS composites with low odour were prepared by adding metallic pigment, adsorbent and extractant into the PC/ABS composite matrix. The effects of the metal pigment, extractant, adsorbent and processing technology on the volatile organic compounds (VOC), condensable substances (FOG) and odour of PC/ABS composites were studied systematically. It was found that upon increasing the content of the metallic pigments, the VOC, FOG and odour of the PC/ABS composites increase rapidly. The adsorbent and extractant can effectively improve the VOC, FOG and odour. When the extractant and adsorbent were used at the same time, the method of adding extractant and adsorbent from the main and the secondary feeding port, respectively, was significantly superior to the method of adding the extractant and adsorbent from the main feeding port together in reducing the VOC, FOG and odour of PC/ABS composites, which displayed a good synergistic effect. When the adsorbent and extractant content are 1.5 and 5.0 parts per hundreds of resin (phr), respectively, the obtained composites have good metallic lustre and environmental friendliness (odour level = 2.0, VOC and FOG: not detected).

High-pressure synthesis, crystal structure, and physical properties of NaB13C2 single crystals

A new boron-rich boride carbide of sodium, NaB13C2 single crystals have been successfully synthesized from the elements under high temperature and high pressure. The crystals are reddish black with a metallic luster and show a regular hexagonal prism shape. NaB13C2 crystallizes into an orthorhombic LiB13C2-type structure with a space group of Imma (No. 74) and the lattice constants are a = 10.9417 Å, b = 5.6756 Å, c = 8.0898 Å. The crystal structure is characterized by a covalent framework of B12 icosahedra connected by CBC chains and Na atoms located in the void of the framework. The measured and calculated Raman spectra of NaB13C2 are in good agreement and show expected oscillations of the covalent framework. The electronic band structures reveal that NaB13C2 is a wide band gap semiconductor with a band gap of 3.36 eV. As a novel wide band gap semiconductor, NaB13C2 may have potential applications in semiconductor field.

A NEW SPECIES OF THE GENUS EXRHYNCHITES VOSS, 1930 (COLEOPTERA: RHYNCHITIDAE) FROM VIETNAM

Exrhynchites storozhenkoi sp. n. is described and illustrated from North Vietnam. The new species differs from other congeners in the body without metallic blue luster, cowered with dense yellow-brown hairs, and sclerotized armament of the endophallus.

Chemical Oxidative Polymerization of Methylene Blue: Reaction Mechanism and Aspects of Chain Structure.

The kinetic regularities of the initial stage of chemical oxidative polymerization of methylene blue under the action of ammonium peroxodisulfate in an aqueous medium have been established by the method of potentiometry. It was shown that the methylene blue polymerization mechanism includes the stages of chain initiation and growth. It was found that the rate of the initial stage of the reaction obeys the kinetic equation of the first order with the activation energy 49 kJ · mol−1. Based on the proposed mechanism of oxidative polymerization of methylene blue and the data of MALDI, EPR, and IR spectroscopy methods, the structure of the polymethylene blue chain is proposed. It has been shown that polymethylene blue has a metallic luster, and its electrical conductivity is probably the result of conjugation over extended chain sections and the formation of charge transfer complexes. It was found that polymethylene blue is resistant to heating up to a temperature of 440 K and then enters into exothermic transformations without significant weight loss. When the temperature rises above 480 K, polymethylene blue is subject to endothermic degradation and retains 75% of its mass up to 1000 K.

PECULIARITIES OF SINGLE CRYSTAL GROWTH OF SOLID SOLUTION IN SYSTEMS Ag6PS5I‒Ag7GeS5I AND Ag7SiS5I‒Ag7GeS5I

The application of innovative resolutions that are technically grounded and economically acceptable with the use of environmentally friendly components is one of the important points at the present stage of human development to promote the ideas of efficient use of energy resources. Superionic conductors take a leading role in solving the problems of energy-saving technologies because electrochemical sensors and solid energy sources based on them can be created. Quaternary silver-containing compounds of argyrodite structure Ag6PS5I, Ag7SiS5I, and Ag7GeS5I have many advantages, in particular chemical stability, high values of ionic conductivity, the ability to form wide series of solid solutions due to the structural features. This work is devoted to the development and optimization of technology for obtaining high-quality single-crystal samples of solid solutions based on compounds of argyrodite structure formed in systems Ag6PS5I‒Ag7GeS5I та Ag7SiS5I‒Ag7GeS5I.
 The synthesis of solid solutions of the investigated systems was carried out by a direct single-temperature method from previously obtained quaternary compounds Ag6PS5I, Ag7SiS5I, and Ag7GeS5I. The maximal temperature of synthesis was 1273 K (exposure 72 h). Cooling to the experimentally selected annealing temperatures of 733 K (Ag6PS5I‒Ag7GeS5I) and 873 K (Ag7SiS5I‒Ag7GeS5I) was performed at a rate of 100 K/h. The annealing was performed for 120 hours.
 Crystal growth of solid solutions based on Ag6PS5I, Ag7SiS5I, and Ag7GeS5I phases was carried out by the directional crystallization from solution-melt by the Bridgman technique. The growth of single crystals was carried out in a three-zone furnace in a quartz container with a conical bottom. The optimal technological regimes for crystal growth of solid solutions of Ag6PS5I‒Ag7GeS5I and Ag7SiS5I‒Ag7GeS5I systems have been established. Grown single crystals of solid solutions Ag6+x(P1-xGex)S5I (х=0.25, 0.5, 0.75) and Ag7(Si1-xGex)S5I (х=0.2, 0.4, 0.6, 0.8) were dark gray color with metallic luster 30-40 mm long and 10-12 mm in diameter. Obtained crystals were investigated by X-ray diffraction analysis. Calculated lattice parameters change according to Vegard’s rule and confirm the formation of solid solutions in studied systems.

Experimental research on fatigue performance of butt welds of corroded Q690 high strength steel

The marine environment was characterized by high humidity and high salinity. Offshore structures faced erosion damage caused by the spray splash, structural durability was severely challenged and tested. In this paper, by simulating the corrosion environment of splash zone, the fatigue test of butt welds of Q690 high strength steel was carried out, and the SN curves of different periods were compared to analyze the influence of corrosion damage on fatigue performance of butt welds of HSS. Based on the damage theory, the degradation law of mechanical properties of specimen was studied. The results show that as the corrosion period increases, more corrosion products were distributed at the butt welds, and the metallic luster gradually darkens. The rust rates of 100 days of corrosion was 8.46%, and the corrosion depth rates of WZ and HAZ were 1.34 mm/a and 1.46 mm/a, respectively. The fatigue limit value of specimen was reduced by 32.7% under high cycle loading. According to the scan results of failure fractures, weld defects and corrosion damage have a greater impact on crack propagation. The damage curve can reflect the fracture formation mechanism. When the stress level was large, the number of fatigue striations decreases, and the cumulative amount of damage gradually increases. The research results are of great significance to the practical engineering application of Q690 high strength steel.

Polysulfide Filter and Dendrite Inhibitor: Highly Graphitized Wood Framework Inhibits Polysulfide Shuttle and Lithium Dendrites in Li–S Batteries

AbstractThe design and manufacture of advanced materials based on biomaterials provide new opportunities to solve many technological challenges. In this work, a highly graphitized wood framework (GWF) with a porous tunnel structure and microvilli is constructed as a multifunctional interlayer to improve the electrochemical performance of lithium–sulfur (Li–S) batteries. The GWF not only retains the 3D transport network of wood, but also offers increased deposition sites for polysulfides through the microvilli which grow on the inner surfaces of the carbon tunnels. Electrochemical tests show that GWF effectively enhances the initial discharge capacity of the Li–S battery to 1593 mAh g−1at 0.05 C, with a low capacity decline of 0.06% per cycle at 1 C. Besides, the GWF interlayer also effectively protects lithium anodes from corrosion by Sx2−, thus they still keep their metallic luster and clean surface even after long charge‐discharge cycles. These enhancements are attributed to the high conductivity, abundant microvilli, and tunnel confinement effects of GWF, which effectively inhibit the shuttle effect of polysulfides by the same principle as nose hairs filtering the air. This work presents a new understanding of bionic/biomaterials and a new strategy to improve the performance of Li–S batteries.

Tamuraite, Ir5Fe10S16, a New Species of Platinum-Group Mineral from the Sisim Placer Zone, Eastern Sayans, Russia

Tamuraite, ideally Ir5Fe10S16, occurs as discrete phases (≤20 μm) in composite inclusions hosted by grains of osmium (≤0.5 mm across) rich in Ir, in association with other platinum-group minerals in the River Ko deposit of the Sisim Placer Zone, southern Krasnoyarskiy Kray, Russia. In droplet-like inclusions, tamuraite is typically intergrown with Rh-rich pentlandite and Ir-bearing members of the laurite–erlichmanite series (up to ~20 mol.% “IrS2”). Tamuraite is gray to brownish gray in reflected light. It is opaque, with a metallic luster. Its bireflectance is very weak to absent. It is nonpleochroic to slightly pleochroic (grayish to light brown tints). It appears to be very weakly anisotropic. The calculated density is 6.30 g·cm−3. The results of six WDS analyses are Ir 29.30 (27.75–30.68), Rh 9.57 (8.46–10.71), Pt 1.85 (1.43–2.10), Ru 0.05 (0.02–0.07), Os 0.06 (0.03–0.13), Fe 13.09 (12.38–13.74), Ni 12.18 (11.78–13.12), Cu 6.30 (6.06–6.56), Co 0.06 (0.04–0.07), S 27.23 (26.14–27.89), for a total of 99.69 wt %. This composition corresponds to (Ir2.87Rh1.75Pt0.18Ru0.01Os0.01)Σ4.82(Fe4.41Ni3.90Cu1.87Co0.02)Σ10.20S15.98, calculated based on a total of 31 atoms per formula unit. The general formula is (Ir,Rh)5(Fe,Ni,Cu)10S16. Results of synchrotron micro-Laue diffraction studies indicate that tamuraite is trigonal. Its probable space group is R3m (#166), and the unit-cell parameters are a = 7.073(1) Å, c = 34.277(8) Å, V = 1485(1) Å3, and Z = 3. The c:a ratio is 4.8462. The strongest eight peaks in the X-ray diffraction pattern [d in Å(hkl)(I)] are: 3.0106(216)(100), 1.7699(420)(71), 1.7583(2016)(65), 2.7994(205)(56), 2.9963(1010)(50), 5.7740(102)(45), 3.0534(201)(43) and 2.4948(208)(38). The crystal structure is derivative of pentlandite and related to that of oberthürite and torryweiserite. Tamuraite crystallized from a residual melt enriched in S, Fe, Ni, Cu, and Rh; these elements were incompatible in the Os–Ir alloy that nucleated in lode zones of chromitites in the Lysanskiy layered complex, Eastern Sayans, Russia. The name honors Nobumichi Tamura, senior scientist at the Advanced Light Source of the Lawrence Berkeley National Laboratory, Berkeley, California.

A review of the genus Anthocomus Erichson, 1840 (Coleoptera, Cleroidea, Malachiidae) species of Inner Asia.

The distribution and species diversity of the genus Anthocomus Erichson, 1840 of Inner Asia are discussed. Nine species, Anthocomus (Celidus) equestris (Fabricius, 1781), Anthocomus (Anthocomus) abdominalis Pic, 1903, A.( A.) coreanus Pic, 1911, A. (A.) cyaneipennis Wittmer, 1940, A. (A.) limbellus (Wittmer, 1953), A. (A.) lineatipennis Wittmer, 1995, A. (A.) mongolicus Wittmer, 1969, A. (A.) similicornis Wittmer, 1999 and A. (A.) testaceoterminalis Wittmer, 1995 known from the region and adjacent territories are reviewed. The placement of four species, ? A. (A.) coreanus Pic, 1911, ? A. (A.) cyaneipennis Wittmer, 1940, ? A. (A.) limbellus (Wittmer, 1953) and ? A. (A.) mongolicus Wittmer, 1969 in the genus Anthocomus Erichson is discussed as doubtful. A new species, Anthocomus (Anthocomus) kovali Tshernyshev, sp. n. from Wexi mountains, Yunnan Province, China is described and illustrated. The new species differs in its monochromous orange-yellow elytra with orange-red apical impressions yellow within, appendages orange-brown, head, pronotum, scutellum and palpi dark brown to black and lacking metallic luster, antennae dark brown.

Metal effect pigments

AbstractMetal effect pigments are luster pigments consisting of platelet-like metallic particles, mostly of aluminum (so-called silver bronzes), copper, copper/zinc (so-called gold bronzes), and zinc flakes. After parallel orientation in their application medium, they show a metal-like luster by reflection of light at the surface of the flat metal particles in one direction. Thus, the pigment particles act similar to small mirrors and lead when orientated parallel in the application system to a reflecting metal luster (metallic effect). Metal effect pigments are used in all relevant application systems such as coatings, paints, plastics, artist paints, cosmetics, printing inks, leather, construction materials, paper, glass, and ceramics. Specific composition, particle size distribution and surface quality determine the coloristic and application technical properties of the individual pigments. Many pigments are coated with a specific surface treatment to improve the quality concerning the stability and the compatibility with the application system. Metal effect pigments are offered in form of powders, pastes, pellets, suspensions or color concentrates. They are manufactured starting from a metal granulate (grit), which is ground under formation of flakes.