Sn Deposits Research Articles

Redox states and protoliths of Late Mesozoic granitoids in the eastern Jiangnan Orogen: Implications for W, Mo, Cu, Sn, and (Au) mineralization

• Late Mesozoic granites in eastern Jiangnan Orogen include 154–136 and 136–126 Ma. • Zircon and biotite parameters reveal redox state of Late Mesozoic granitoids. • Early stage granitoids originate from metasedimentary & volcanic–sedimentary rocks. • Late stage granitoids originate from anatexis with various mantle-derived melts. • Magmatic redox states and protoliths controlled the diverse mineralization . Late Mesozoic magmatism is extensively developed in the eastern Jiangnan Orogen and is closely related to W, Mo, Cu, Au, and Sn mineralization. Late Mesozoic granitoids show various petrological and mineralizing features that vary spatially (northern Jiangxi Province and southern Anhui Province) and temporally (early stage: 154 to 136 Ma, late stage: 136 to 126 Ma). In this study, we analyzed zircon trace element data from four Late Mesozoic granitoids. Together with published zircon trace element data and biotite compositions from granitoids in the eastern Jiangnan Orogen and W–Sn, Mo and Cu deposits, we use these data to determine the magmatic redox state of the Late Mesozoic granitoids, which is useful in determining mineralization competency and is instructive during exploration. The results show that early stage granitoids of southern Anhui Province are oxidized, characterized by high zircon Ce 4+ /Ce 3+ (median = 278), Ce/Nd (median = 17.1), and Eu N /Eu N * (median = 0.42) ratios, and high biotite Fe 3+ /Fe 2+ ratios (median = 0.23) and X Mg values (median = 0.48). The late stage granitoids of southern Anhui Province are relatively reduced, showing lower zircon Ce 4+ /Ce 3+ (median = 49.7), Ce/Nd (median = 12.7), and Eu N /Eu N * (median = 0.16) ratios, and lower biotite Fe 3+ /Fe 2+ ratios (median = 0.11) and X Mg values (median = 0.38). The early stage granitoids of northern Jiangxi Province show a somewhat reduced redox state. They have comparatively low zircon Ce 4+ /Ce 3+ (median = 17.28), Ce/Nd (median = 4.50), and Eu N /Eu N * (median = 0.17) ratios, and comparatively low biotite Fe 3+ /Fe 2+ ratios (median = 0.07, N = 160) and X Mg values (median = 0.35). The late stage granitoids of northern Jiangxi Province are strongly reduced, characterized by low zircon Ce 4+ /Ce 3+ (median = 17.03), Ce/Nd (median = 0.72), and Eu N /Eu N * (median = 0.02) ratios, and low biotite Fe 3+ /Fe 2+ ratios (median = 0.06) and X Mg values (median = 0.25). Geochemical and isotopic data reveal that early stage granitoids in northern Jiangxi Province were sourced from Neoproterozoic metasedimentary rocks, whereas those in southern Anhui Province originated from Neoproterozoic volcanic–sedimentary sequences. The late stage granitoids in the eastern Jiangnan Orogen formed under an extensional regime and were generated by anatexis with various mantle inputs. The results suggest that early stage granitoids of southern Anhui Province have the potential for Cu (>1 Mt) and Mo (>0.3 Mt) mineralization, whereas late stage granitoids are related to W, Cu (<1 Mt), and Mo (<0.3 Mt). In northern Jiangxi Province, the highly evolved and relatively reduced early stage granitoids have more potential to form large- to super-large-scale W mineralization, with subordinate Cu (<1 Mt) and Mo (<0.3 Mt) mineralization, whereas the similarly reduced and evolved late stage granitoids are closely associated with large- to super-large-scale Sn and W mineralization, with subordinate Cu (<1 Mt) and Mo (<0.3 Mt) mineralization. Different magmatic redox states and protoliths have controlled diverse mineralization in the eastern Jiangnan Orogen.

Geological characteristics and metallogenic age of Tengshan'ao Sn deposit in Dayishan of South Hunan and its prospecting significance

The Tengshan'ao Sn deposit, located at the Dayishan ore field, Nanling Range, is one of the recently explored deposits in this region. In this study, LA-MC-ICP-MS cassiterite U–Pb and muscovite 40Ar-39Ar isotopic dating analyses for altered granite-type Sn ores yielded ages of 156.7 ± 4.3 Ma and 151.1 ± 1.5 Ma, respectively. These ages are consistent to the LA-MC-ICP-MS zircon U–Pb age of the fine-grained two-mica monzogranite (158.2 ± 1.6 Ma), indicating a coeval magmatism and mineralization for the Late Jurassic Tengshan'ao Sn deposit. It is further demonstrated that the formation of this deposit is related to the Early Yanshanian (160-150 Ma) large-scale diagenesis and mineralization in Nanling Range. It is suggested that the late-stage fine-grained two-mica (muscovite) granite has an indicative significance for searching the altered granite type Sn polymetallic mineralization.

Cu Plating with Sn and Subsequent Bronze Formation under Mild Conditions

In a well-known bronze plating experiment, a Cu coupon is subjected to Sn plating and heating with a Bunsen burner. Currently, aqueous NaOH or HCl is typically used as the plating solution; however, the use of a strong acid or base provides operational risks, particularly in educational settings (e.g., schools). Herein, we introduce a modified method that uses aqueous NaHSO4 as the plating solution. This method reduces the operational risks and allows for the smooth deposition of silver-white Sn onto the Cu coupon in a higher yield than that obtained by the HCl method, which uses 30 times the concentration of the solute. When the Sn-plated Cu coupon is heated, it changes to bronze plating. This experiment is ideal for high school students, as it allows them to observe metal plating and solid diffusion.

Fabrication of Cu-rich CZTS thin films by two-stage process: Effect of gas flow-rate in sulfurization process

In this study, CZTS thin films were prepared using a two-stage process consisting of sputter deposition of Cu, Sn and ZnS layers on the glass substrates to form CuSn/ZnS/Cu stacked precursor films followed by sulfurization process under various flow-rate (0, 20, 40, 60, 80, 100 sccm) of Ar+H2 mix gas in a tubular furnace. The EDX measurements of the precursor and reacted films are Cu-rich and Zn-rich composition. However, Zn and Sn loss was observed for samples annealed under the flow-rate of gas above the 60 sccm. The XRD pattern of the samples showed diffraction peaks of pure kesterite CZTS structure and the FWHM values extracted from their XRD patterns and W-H plot calculations demonstrated that CZTS-40 thin film had a more desired crystallite size. The Raman spectra of the samples confirmed the formation of CZTS phase for all samples and indicated the formation of some secondary phases such as Cu2SnS3, SnS2, Sn2S3 except for CZTS-40 thin film. All the samples displayed dense and polycrystalline microstructure according to their SEM images. The optical band gap values of CZTS samples showed variation between 1.40 and 1.48 eV. The room-temperature PL spectra of the samples revealed a broad band that had a peak value at around 1.36–1.40 eV that are close to the optical band gap values for prepared CZTS samples.

Trace element composition and U-Pb ages of cassiterite from the Bolivian tin belt

The Bolivian tin belt is a metallogenic province in the Eastern Cordillera of the Andes known for its Sn, W, Ag, and base metal deposits. Cassiterite, which is a major constituent in many magmatic-hydrothermal ore deposits from the Bolivian tin belt, can incorporate dozens of elements within its crystal lattice, making it a useful geological tracer mineral and also a potential host of critical elements. New U-Pb dating of cassiterite yields Late Triassic (Kellhuani deposit) and Late Oligocene to earliest Miocene (Viloco, Huanuni, and Llallagua deposits) ages. These ages confirm that Sn mineralization in the Bolivian tin belt occurred at least in two separate events during two major magmatic episodes apparently triggered by mantle upwelling, decompression melting, and basalt production promoting high heat flow into the overlying crust. The composition of studied hydrothermal cassiterite yields some geochemical trends that are attributed to its distance to the causative intrusion and/or level of emplacement. For example, cassiterite is generally enriched in Nb and Ta and yields higher Ti/Zr and Ti/Sc ratios in samples from xenothermal ore deposits located adjacent to intrusive complexes relative to shallow xenothermal and epithermal ore deposits. Therefore, these geochemical trends in cassiterite are useful tracers pointing to magmatic-hydrothermal centers. REE distribution in cassiterite was likely influenced by boiling processes, which resulted in tetrad-type irregularities. Cassiterite from the Bolivian tin belt is unattractive as a source for Nb (interquartile range [IQR] 4.84–0.037 ppm), Ta (IQR 0.0924–0.0126 ppm), and Ge (IQR 3.92–0.776 ppm). Some deposits, however, contain cassiterite relatively enriched in In (IQR 96.9–9.78 ppm, up to 1414 ppm) and Ga (IQR 92.1–3.03, up to 7437 ppm), that could constitute an attractive supplementary source for these elements in addition to sulfide minerals in the same deposits.

Geological characteristics, geodynamic setting of magmatism and metallogeny of Early Cretaceous Sn (W) deposits in southeastern coastal belt of China, and their implication for exploration

我国华南是世界上最重要的锡矿资源省之一，其锡矿成矿时代从新元古代、古生代、早中生代至晚中生代均有发育，其中以晚中生代锡矿成矿作用最为重要，成矿集中在中晚侏罗世（160~150Ma）和晚白垩世（100~80Ma）。然而，最近在东南沿海成矿带新识别出一期早白垩世锡（钨）（145~130Ma）成矿事件，改变了以往华南锡（钨）矿床时空分布格局。本文在详细介绍东南沿海早白垩世锡（钨）矿床地质特征基础上，系统总结了其成岩成矿时空分布，并与南岭板内锡（钨）成矿作用进行对比，浅析了早白垩世锡（钨）矿的成岩成矿背景和找矿潜力。研究显示，早白垩世锡（钨）成矿主要发生在东南沿海成矿带的粤东和赣州会昌地区，矿床类型以斑岩型和锡石硫化物型为主。与成矿有关的岩石为黑云母花岗岩和花岗斑岩，成因上属于高分异I型或A型，与南岭板内锡（钨）矿相比，具有较高的锆石ε_Hf（t）值和较低δ¹⁸O值，以及较高成岩温度，表明成岩过程中有较多新生地壳或地幔物质加入。结合区内发育同时期基性岩脉，认为华南这期早白垩世锡（钨）矿形成于岩石圈伸展背景，与古太平洋板块俯冲后撤有关。最后指出覆盖大面积晚白垩世火山岩的东南沿海地区，火山岩盖层下部具有寻找该期锡（钨）矿床的找矿潜力。;South China is one of the most important tin provinces in the world, and the tin mineralization formed from Neoproterozoic, Early Paleozoic, to Early and Late Mesozoic are well developed in this area. In particular, the Late Mesozoic tin mineralization is the most important one, happened at two age peaks of the Middle-Late Jurassic (160~150Ma) and Late Cretaceous (100~80Ma), respectively. However, an Early-Cretaceous (145~130Ma) tin (tungsten) metallogenic event has also been newly recognized in southeastern coastal belt of China. This makes a change in temporal-spatial framework of tin (tungsten) deposits. In this paper, based on detailed observations of geological characteristics of the Early Cretaceous tin (tungsten) deposits in southeastern coastal belt, we summarize the temporal-spatial distribution of these deposits and their associated magmatisms, and compared them with those in the Nanling Range, in order to identify their metallogenic geodynamic setting and implications for metallogenic potential. The Early Cretaceous tin (tungsten) deposits are mainly developed in the coastal eastern Guangdong Province and Huichang district of the southern Jiangxi Province. Genetically, the tin mineralization mainly comprises porphyry and cassiterite-sulfide-vein types, and associated granitoids include biotite granite and granitic porphyry characterized by high-fractionated I- and A-type affinities. Compared with those in the Nanling Range, these granites display higher zircon ε_Hf(t) and δ¹⁸O values, as well as higher magma temperatures, indicating a contribution of more mantle or juvenile crustal components. Given the coeval mafic dikes in the region, we suggest that the Early Cretaceous tin (tungsten) deposits were formed in the setting of lithospheric extension, triggered by the retreat of the subducting paleo-Pacific plate. Finally, we suggest that there is potential for tin (tungsten) exploration under the large-scale cover of Late Cretaceous volcanic rocks in southeastern coastal belt of China.

Extraction of fractionated interstitial melt from a crystal mush system generating the Late Jurassic high-silica granites from the Qitianling composite pluton, South China: Implications for greisen-type tin mineralization

High-silica granites (> 74 wt% SiO2) in the Nanling Range are associated with important W–Sn deposits. Their petrogenesis remains controversial. The Qitianling composite pluton, one of the Mid–Late Jurassic W–Sn-related granitic plutons in the Nanling Range, comprises dominantly the main-phase medium- to coarse-grained K-feldspar megacrystic hornblende biotite monzogranites and biotite monzogranites (mostly < 70 wt% SiO2) in the outer zone, and minor fine-grained alkali-feldspar granites (high-silica granites with ~75 wt% SiO2) in the inner zone. SHRIMP zircon U–Pb dating indicates that the high-silica granites were emplaced at 154–155 Ma, coeval with the main-phase granites (163–153 Ma) within the analytical error uncertainty. The whole-rock Nd (εNd(t) = −6.85 to −6.56) and zircon Hf–O (εHf(t) = −12.2 to −2.2 and δ18OVSMOW = 7.15‰ to 9.19‰) isotopic compositions of the high-silica granites are indistinguishable from those of the main-phase granites, implying that they are derived from the same sources. Petrographic, mineralogical and geochemical data indicate that both granite types have A2-type affinity, with the high-silica variant characterized by more evolved chemical compositions, higher Rb/Sr, lower Nb/Ta and Zr/Hf ratios, more F enrichment, and more distinct REE tetrads. Based on the geochemical data, trace element modeling and recent studies on the fractionation processes in silicic magma system, we propose that the Qitianling granites have undergone a high degree differentiation in a crystal mush system. The high-silica granites represent the highly-fractionated interstitial melt that was extracted from the crystal mush system, whereas the main-phase granites represent the residual crystal mush consisting of the ‘cumulate crystals’ and trapped interstitial melt. The extraction is inferred to have occurred when the crystallinity of the mush reached about 67–76%, at least for the most evolved sample of the high-silica granites, and the residual crystal mush might have trapped about 15–25% interstitial melt. The highly-fractionated high-silica granites with high melting temperature and low oxygen fugacity are responsible for the greisen-type tin mineralization at the Furong tin deposit.

Tin Enrichment in Magmatic-Hydrothermal Environments Associated with Cassiterite Mineralization at Ardlethan, Eastern Australia: Insights from Rb-Sr and Sm-Nd Isotope Compositions in Tourmaline

Abstract Primary cassiterite mineralization is often associated with highly evolved granites, but the magmatic and hydrothermal processes that produce these deposits are often difficult to decipher. In this study, we employed the chemical and Sr-Nd isotope compositions of tourmaline to monitor processes of Sn enrichment in the magmatic and hydrothermal stages of the Ardlethan granite (Australia) and its associated Sn deposits. Initial 87Sr/86Sr (0.710–0.717) and ɛNd (–5.0 to −1.0) values of late magmatic tourmalines indicate derivation of the Ardlethan granite via an assimilation-fractional crystallization (AFC) process in which incorporation of Ordovician sediment into an I-type granitic parental magma produced an enrichment of Sn at least 30 times over that of the assumed mafic-dominated igneous source of the granite. The rare earth element and Sn concentrations of tourmaline in the greisen deposits together with δ18O of coprecipitated quartz indicate that exsolution of a late-stage, Cl-rich fluid from the Ardlethan granite led to cassiterite mineralization in these deposits. In contrast the Fe/(Fe + Mg) and initial εNd (–9.2 to −12.9) compositions of tourmaline that coprecipitated with cassiterite in the large breccia pipes adjacent to the Ardlethan granite suggest that granite-derived fluids scavenged Sn by chemical leaching of an older S-type granite that hosts the pipes. This study shows that tourmaline can act as a robust monitor of key geologic processes in complex and dynamic magmatic-hydrothermal Sn systems and that its 87Sr/86Sr and ɛNd isotope compositions are especially useful for constraining the nature of magmatic and hydrothermal sources that contributed to these deposits.

Electrochemical Behavior and Electrodeposition of Sn Coating from Choline Chloride–Urea Deep Eutectic Solvents

The electrochemical behavior and electrodeposition of Sn were investigated in choline chloride (ChCl)–urea deep eutectic solvents (DESs) containing SnCl2 by cyclic voltammetry (CV) and chronoamperometry techniques. The electrodeposition of Sn(II) was a quasi-reversible, single-step two-electron-transfer process. The average transfer coefficient and diffusion coefficient of 0.2 M Sn(II) in ChCl–urea at 323 K were 0.29 and 1.35 × 10−9 cm2∙s−1. The nucleation overpotential decreased with the increase in temperature and SnCl2 concentration. The results of the chronoamperometry indicated that the Sn deposition on tungsten electrode occurred by three-dimensional instantaneous nucleation and diffusion controlled growth using the Scharifker–Hills model. Scanning electron microscopy (SEM) showed that the morphology of the deposits is uniform, as a dense and compact film prepared by potentiostatic electrolysis on Cu substrate. X-ray diffraction (XRD) analysis revealed that the deposits were pure metallic Sn.

Nanostructured Sn Plating and Pre-Lithiation on Cu Current Collector for Anode-Free Lithium Batteries

The fast and growing employment of Li-ion batteries in automotive and electrical mobility is pushing research towards the development of higher energy density and safer Li-ion batteries. Regarding the anodic material, metal and semi-metals as Al, Sn, Ag and Si are known to electrochemically alloy at low potential with lithium resulting in extremely high specific capacity, up to 4200 mAh/g for Li22Si5. However, severe issues as volumetric expansion and non-reversible lithium trapping strongly limit their cyclability and performances.[1] Anode-free Li battery (AFLB) strategy is a promising alternative to find a good compromise between safety and energy and power density because of the absence of an anodic active material in assembly phase. However, these systems suffer from severe challenges, including low coulombic efficiency (CE) due to intrinsic unstable interface that rapidly leads to dendritic growth and short-circuit.[2] To overcome this problem, nano-structuring of current collector has been demonstrated to be a valid approach to stabilize Li plating and stripping without dendrites formation.[3,4,5] In this work, we address current collector nano structuring by Sn plating as an efficient route for reversible Li plating/stripping. Interface stability is correlated with morphology of Sn deposits on Cu current collector in different conditions. Sn deposits were examined by AFM, SEM and XRD analysis and electrochemical behavior by galvanostatic charging and discharging cycles as well as EIS measurements. Sn pre-lithiation is also investigated as suitable strategy to further smoothing Li plating.

Fabrication and Electrochemical Performance of TiO2-TiN/Sn-SnO2 Composite Films for High Capacity and High Conductivity Lib Anodes

Recently, anodic nanoporous TiO2 films have gained widespread attention as promising anode candidates for Li ion batteries to replace traditional C-based anodes. TiO2 delivers very small volume expansion (<4%) and works at a relatively high working voltage (1.7 V vs. Li/Li+) during Li+ insertion/extraction. This eliminates the influence from the solid electrolyte interface (SEI) layer and avoid the risk of lithium electrodeposition during charge/discharge process, thus further ensuring the cycling stability and safety of batteries. However, the development of TiO2 materials as LIB anodes is limited by its poor electric conductivity and low theoretical capacity. Therefore, we propose a new approach to fill Sn-based materials, which possess around 3 times theoretic capacity higher that the C-based anode, into the nanoporous anodic TiO2 films. Since the TiO2 nanostructure can alleviate the volume expansion of Sn-based materials, the synergistic effect of Sn with high capacity and TiO2 with large surface area is expected.In this study, we first formed nanoporous TiO2-TiN composite films on Ti foils by a smart anodization in NO3 –-based solutions. The inclusion of conductive TiN component in TiO2 matrix film improves the electronic conductivity effectively, which enables the successive electrodeposition on anodic TiO2 film. Then, the nanoporous TiO2-TiN composite films were used as matrix films to deposit Sn and/or SnO2 nanoparticles by a cathodic electrodeposition in acidic baths containing different Sn ions. The electric conductivity and nanostructures were tailored through anodizing process to perform successive electrodeposition. The microstructures, chemical composition, and crystalline structure of the anodized specimens before and after annealed were investigated FE-SEM (EDS), TEM (FIB), and XPS. Moreover, the cyclic voltammetric behaviors, impedance spectra, and charge-discharge performances of various composite films on Ti foils were investigated as binder-free anode materials for Li ion secondary batteries.Fig.1a-b shows the FE-SEM images of surface and cross section of TiO2-TiN composite films. An ordered nanoporous structure is obtained, with parallel pores of 50-100 nm in diameter and around 3-μm thickness after anodization for 90 min. Fig.1c shows the surface morphology of a TiO2-TiN/Sn composite film by electrodeposition in a Sn2+-based solution for 25 min. A granular Sn-based film with particle size of 100-300 nm in diameter formed on the anodic TiO2-TiN film. This indicates that the prolonged electrodeposition led to the filling of Sn not only inside but also on the anodic TiO2-TiN film. XPS analysis revealed that Sn deposits existed in metallic Sn and Sn oxides as SnO and/or SnO2. Moreover, it is confirmed by TEM observation that the nanocrystalline Sn-SnO2 deposits filled in the porous TiO2-TiN film. It is normally that the particles emerging on the film surface are larger than the pores of TiO2-TiN film.Fig.1d demonstrates the cycling performance and coulombic efficiency of TiO2-TiN/Sn-SnO2 and TiO2-TiN composite films on Ti sheets at 30 mA cm-2 for the first cycle and then 80 mA cm-2. The initial capacity of TiO2-TiN/Sn-SnO2 is 2100 μA h cm-2, which is around 5 times larger than the TiO2-TiN matrix film of 396 μA h cm-2. After 40 cycles, the capacity of the composite film remains 1153 μA h cm-2 and 4.6 times higher than the film without Sn electrodeposition. Since the nanoporous structure of TiO2-TiN can alleviate the volume expansion of Sn-based particles inside, the capacity deterioration can be mainly ascribed to the Sn-based particles overflowed on the surface, which may fall off or crush during charge/discharge process by the large volume expansion. Moreover, it was found from the EIS measurement that the internal electrical resistance of the TiO2-TiN composite film decreased considerably after the electrodeposition of the Sn-based materials, in proportional to the deposition time. Therefore, electrodeposition of Sn-based material in porous TiO2-TiN films is an effective approach to enhance the capacity and to improve the conductivity of the electrode material. Nevertheless, optimizing the conditions of anodization Ti base materials and Sn-based electrodeposition are necessary and will be an issue in the future study. Figure 1

Tourmaline as a Tracer of Late-Magmatic to Hydrothermal Fluid Evolution: The World-Class San Rafael Tin (-Copper) Deposit, Peru

Abstract The world-class San Rafael tin (-copper) deposit (central Andean tin belt, southeast Peru) is an exceptionally large and rich (&amp;gt;1 million metric tons Sn; grades typically &amp;gt;2% Sn) cassiterite-bearing hydrothermal vein system hosted by a late Oligocene (ca. 24 Ma) peraluminous K-feldspar-megacrystic granitic complex and surrounding Ordovician shales affected by deformation and low-grade metamorphism. The mineralization consists of NW-trending, quartz-cassiterite-sulfide veins and fault-controlled breccia bodies (&amp;gt;1.4 km in vertical and horizontal extension). They show volumetrically important tourmaline alteration that principally formed prior to the main ore stage, similar to other granite-related Sn deposits worldwide. We present here a detailed textural and geochemical study of tourmaline, aiming to trace fluid evolution of the San Rafael magmatic-hydrothermal system that led to the deposition of tin mineralization. Based on previous works and new petrographic observations, three main generations of tourmaline of both magmatic and hydrothermal origin were distinguished and were analyzed in situ for their major, minor, and trace element composition by electron microprobe analyzer and laser ablation-inductively coupled plasma-mass spectrometry, as well as for their bulk Sr, Nd, and Pb isotope compositions by multicollector-inductively coupled plasma-mass spectrometry. A first late-magmatic tourmaline generation (Tur 1) occurs in peraluminous granitic rocks as nodules and disseminations, which do not show evidence of alteration. This early Tur 1 is texturally and compositionally homogeneous; it has a dravitic composition, with Fe/(Fe + Mg) = 0.36 to 0.52, close to the schorl-dravite limit, and relatively high contents (10s to 100s ppm) of Li, K, Mn, light rare earth elements, and Zn. The second generation (Tur 2)—the most important volumetrically—is pre-ore, high-temperature (&amp;gt;500°C), hydrothermal tourmaline occurring as phenocryst replacement (Tur 2a) and open-space fillings in veins and breccias (Tur 2b) and microbreccias (Tur 2c) emplaced in the host granites and shales. Pre-ore Tur 2 typically shows oscillatory zoning, possibly reflecting rapid changes in the hydrothermal system, and has a large compositional range that spans the schorl to dravite fields, with Fe/(Fe + Mg) = 0.02 to 0.83. Trace element contents of Tur 2 are similar to those of Tur 1. Compositional variations within Tur 2 may be explained by the different degree of interaction of the magmatic-hydrothermal fluid with the host rocks (granites and shales), in part because of the effect of replacement versus open-space filling. The third generation is syn-ore hydrothermal tourmaline (Tur 3). It forms microscopic veinlets and overgrowths, partly cutting previous tourmaline generations, and is locally intergrown with cassiterite, chlorite, quartz, and minor pyrrhotite and arsenopyrite from the main ore assemblage. Syn-ore Tur 3 has schorl-foititic compositions, with Fe/(Fe + Mg) = 0.48 to 0.94, that partly differ from those of late-magmatic Tur 1 and pre-ore hydrothermal Tur 2. Relative to Tur 1 and Tur 2, syn-ore Tur 3 has higher contents of Sr and heavy rare earth elements (10s to 100s ppm) and unusually high contents of Sn (up to &amp;gt;1,000 ppm). Existence of these three main tourmaline generations, each having specific textural and compositional characteristics, reflects a boron-rich protracted magmatic-hydrothermal system with repeated episodes of hydrofracturing and fluid-assisted reopening, generating veins and breccias. Most trace elements in the San Rafael tourmaline do not correlate with Fe/(Fe + Mg) ratios, suggesting that their incorporation was likely controlled by the melt/fluid composition and local fluid-rock interactions. The initial radiogenic Sr and Nd isotope compositions of the three aforementioned tourmaline generations (0.7160–0.7276 for 87Sr/86Sr(i) and 0.5119–0.5124 for 143Nd/144Nd(i)) mostly overlap those of the San Rafael granites (87Sr/86Sr(i) = 0.7131–0.7202 and 143Nd/144Nd(i) = 0.5121–0.5122) and support a dominantly magmatic origin of the hydrothermal fluids. These compositions also overlap the initial Nd isotope values of Bolivian tin porphyries. The initial Pb isotope compositions of tourmaline show larger variations, with 206Pb/204Pb(i), 207Pb/204Pb(i), and 208Pb/204Pb(i) ratios mostly falling in the range of 18.6 to 19.3, 15.6 to 16.0, and 38.6 to 39.7, respectively. These compositions partly overlap the initial Pb isotope values of the San Rafael granites (206Pb/204Pb(i) = 18.6–18.8, 207Pb/204Pb(i) = 15.6–15.7, and 208Pb/204Pb(i) = 38.9–39.0) and are also similar to those of other Oligocene to Miocene Sn-W ± Cu-Zn-Pb-Ag deposits in southeast Peru. Rare earth element patterns of tourmaline are characterized, from Tur 1 to Tur 3, by decreasing (Eu/Eu*)N ratios (from 20 to 2) that correlate with increasing Sn contents (from 10s to &amp;gt;1,000 ppm). These variations are interpreted to reflect evolution of the hydrothermal system from reducing toward relatively more oxidizing conditions, still in a low-sulfidation environment, as indicated by the pyrrhotite-arsenopyrite assemblage. The changing textural and compositional features of Tur 1 to Tur 3 reflect the evolution of the San Rafael magmatic-hydrothermal system and support the model of fluid mixing between reduced, Sn-rich magmatic fluids and cooler, oxidizing meteoric waters as the main process that caused cassiterite precipitation.

Mn–Cu Transmetalation as a Strategy for the Assembly of Decoupled Metal–Organic Networks on Sn/Cu(001) Surface Alloys

Surface alloying of Cu(001) by Sn deposition is a finely controllable method of tuning the degree of copper reactivity in order to drive the on-surface assembly and synthesis of metal–organic coord...

The world-class Jiangnan tungsten belt: Geologicalcharacteristics, metallogeny, and ore deposit model

The Jiangnan tungsten belt (JNB), a newly identified in the past decade, has a total resource of more than 6 Mt WO3 and still has a good potential for further prospecting. The JNB, located along the Jiangnan Massif (JM) and its eastern extensional areas, is adjacent to and parallel with the Middle-Lower Yangtze River porphyry-skarn Cu-Mo-Au-Fe belt (MLYRB) at north. Both JNB and MLYRB have the same mineralization periods, i.e., 150–135 and 130–125 Ma. The tungsten mineralization in JNB developed at the proximal contact of granite plutons, whereas the Pb-Zn±Cu veins occurs at the distal areas, exhibiting an obvious zoning in space. Apart from the Dongping quartz vein wolframite deposit, the other W deposits in the JNB belong to porphyry and skarn types. The Zhuxi scheelite skarn deposit with 3.44 Mt of WO3 is the largest one over the world. Meanwhile, the exploration of the Dahutang super-large, and Dongyuan and Yangchuling large porphyry W deposits has proven the porphyry is a new major W type except for both skarn and quartz vein types which were recognized before. Moreover, it is interesting to find unusual scheelite-bearing anorthosite and albitite dikes, which cut through the skarn ores in the Zhuxi deposit area. The scheelite-bearing albitite is proposed to crystallize from Al-, Si-, P-, W-, and F-rich residual magma whereas the scheelite-bearing anorthosite formed when the residual magma was contaminated by pure limestone in a reducing environment. The granitoids associated with W deposits and W-Mo deposits in the JNB are biotite monzonite and granodiorite, respectively. According to the petrology, geochemistry and major accessory minerals, the ore-related granitoids can be recognized as S type (or ilmenite series) with peraluminous nature and I type (or magnetite series) with metaluminous nature. Geochemical and Sr-Nd-Hf isotopic data indicate the W deposits-related granitoids were derived from the remelting of the Neoproterozoic phyllite and slate and the W-Mo deposits-related granitoids were also derived from the same strata but with input of mantle materials. According to the sources of granitoids and the skarn mineral assemblages as well as mineral chemistry it can be recognized as reduced W and the oxidized W-Mo deposits. Usually the reduced W deposit appears as large and super-large scale, such as the Zhuxi and Dahutang whereas the oxidized W-Mo as relatively smaller. A tectonic model is suggested to explain the two periods of mineralization in both JNB and MLYRB, which are corresponding to oblique subduction of Izanagi plate in 150–135 Ma at quite low angle and the extension tectonic regime of post-subduction at 130–125 Ma, respectively. The porphyry-skarn Cu-Mo-Au-Fe system in early period and apatite-magnetite system in late period along MLYRB are related to the granitoids derived from the slab subducted slab and the stagnant slab whereas tow periods of porphyry-skarn as well as quartz vein type W(Sn) deposits are associated with the granitoids which were remelted from the Neoproterozoic phyllite deduced from mantle underplated. Moreover, a deposit model is set up for the relationship among the porphyry-skarn W and W-Mo, and distal Pb-Zn-Ag±Cu veins, which can be referenced for the further prospecting in JNB and the regions with similar tectonic setting.

Effects of additives on the electrodeposition of Zn Sn alloys from choline chloride/ethylene glycol-based deep eutectic solvent

Abstract The effects of additives on the electrodeposition of Zn Sn alloy from aqueous electrolyte have been the subject of considerable interest in the literature; however, to date there has been little consideration of their effects on alloy electrodeposition from Deep Eutectic Solvents (DESs). This work will show, for the first time, the effects of boric acid, ammonium chloride and nicotinic acid on the electrodeposition of Zn Sn alloys on copper from a DES consisting of a stoichiometric 1:2 mix of choline chloride and ethylene glycol (Ethaline 200). Cyclic voltammetry has been used to study the electrochemical properties of the Zn Sn electrolyte, and the resultant surface morphologies, composition and roughness of the Zn Sn coating were revealed via SEM/EDX and AFM, demonstrating that boric acid and nicotinic acid function as very effective brighteners, producing highly uniform and smooth Zn Sn deposits. It was found that these additives strongly affect the morphology, composition, and roughness of the Zn Sn coating. XRD was also used to examine the crystal structure of Zn Sn coatings, where it was found that the phase composition of the deposits depends on the additive(s) used. In addition, corrosion of the Zn Sn alloy in salty media was measured using the Tafel method.

Contribution of crustal and mantle sources to genesis of Sn, B and Pb-Zn deposits in South Sikhote-Alin subprovince (Russian Far East): Evidence from high–precision MC-ICP-MS lead isotope study

South Sikhote-Alin metallogenic subprovince (SSAP) is located in the southern part of the Sikhote-Alin orogenic belt. It encompasses more than one hundred well-known deposits and occurrences of boron, tin, lead, and zinc. These deposits have been genetically related to the Late Cretaceous and Paleocene granitoid magmatism. Pb isotope composition was measured using the MC-ICP-MS method in 20 SSAP deposits. Pb isotope ratios (48 samples of galena) vary within narrow limits: 206Pb/204Pb ranges from 18.321 to 18.474, 207Pb/204Pb − 15.608–15.655, and 208Pb/204Pb 38.601–38.796. The high degree of homogeneity of the Pb isotope composition and absence of correlations between the lead isotope characteristics of the deposits, on the one hand, and the age and type of ore mineralization, on the other, indicate the presence of a regional uniform Pb source for all the SSAP deposits. The results of Pb-Pb studies of the different rocks of the SSAP suggest that the source was most likely the Mesozoic sedimentary sequences of the Sikhote-Alin accretionary complexes. In turn, individual lead isotope characteristics of the SSAP deposits are caused by varibale contribution of mantle source to the overall balance of lead.

Effect of thiourea on electrocrystallization of Cu–Sn alloys from sulphate electrolytes

In this work, the effect of thiourea on the initial stages of the Cu–Sn electrodeposition in the potential range of the underpotential deposition (UPD) of tin from the sulphate electrolyte was studied by linear sweep voltammetry. The mechanism of Cu–Sn alloy nucleation and growth was proposed based on the results of chronoamperometry, chronopotentiometry, and scanning electron microscopy. Thiourea in the concentrations of 0.001–0.010 g/L showed a significant inhibitory effect on the reduction of copper ions. Analysis of the current-time dependencies revealed that Cu–Sn deposition in the UPD region of tin from thiourea-containing solutions proceeds through 3D diffusion-controlled growth of copper clusters. The nucleation type and the main nucleation parameters were calculated based on the Scharifker and Hills theoretical model. Galvanostatic experiments proved that the UPD of tin occurs on the surface of initially formed copper clusters. Surface characterization of Cu–Sn coatings deposited in the presence of thiourea showed a good correlation with electrochemical experiments.

The relationship between ductile shear zone and mineralization in the Jiufeng Sn deposit, northern Guangxi, South China: Evidence from structural analysis and cassiterite U-Pb dating

The Jiufeng Sn deposit is located in the outer contact zone southwest of the Neoproterozoic Motianling granitic pluton, in northern Guangxi, South China. The deposit is characterized by a NNE-striking, 30–200-m-wide ductile shear zone, named the Jiufeng ductile shear zone. Majority of the Sn orebodies, including four large ones, are hosted by the shear zone. Field and microstructural observations, electron backscatter diffraction measurements, and magnetic fabric analyses show that the shear zone is characterized by sinistral thrust shearing. The shear zone has also slightly modified the Sn orebodies. Quartz in the shear zone exhibits core-mantle structure and undulose extinction. Quartz has experienced significant sub-grain rotation and grain-boundary migration recrystallization. Lattice preferred orientation analysis reveals primarily basal <a>, rhomb <a>, and prism <a> slips. Cassiterite grains in the shear zone, however, demonstrate brittle deformation. Therefore, the deformation temperature during the ductile shearing is estimated lower than 650 °C and below U-Pb closure temperature of cassiterite. As such, the U-Pb isotopic composition of the cassiterite was not disturbed by the shearing and the U-Pb age of the cassiterite could be used for the age of the Sn mineralization. LA-ICP-MS U-Pb dating of cassiterite grains selected from a cassiterite-bearing tourmalinite sample performed in this study yielded a Tera–Wasserburg U-Pb lower intercept age of 832.3 ± 5.3 Ma. This age is consistent within error with that of the neighboring Neoproterozoic Motianling granitic pluton, which suggests a close genetic relationship between the Sn mineralization and the granitic magmatism. Studies show that the Jiufeng ductile shear zone was produced by a widespread Caledonian (or Kwangsian) tectonic event in South China, indicating that the shearing was much later than the Sn mineralization and has no generic relationship to the Sn deposit.

FeCeOx Supported Ni, Sn Catalysts for the High-Temperature Water–Gas Shift Reaction

In this work, the effect of monometallic Ni or Sn and bimetallic NiSn deposition on the activity of FeCeOx catalysts in high-temperature water–gas (HT-WGS) reactions was investigated. It was found that the HT-WGS performance of FeCeOx has significantly improved after the deposition of Sn together with Ni on it. Furthermore, the bimetallic NiSn/FeCeOx catalyst showed higher activity compared to the monometallic Ni/FeCeOx and Sn/FeCeOx catalysts within the tested temperature range (450–600 °C). Although the Ni/FeCeOx catalyst showed methanation activity at a temperature below 550 °C, the NiSn/FeCeOx catalyst suppressed the methane formation to zero in the WGS. Besides, the NiSn/FeCeOx catalyst exhibited an excellent time-on-stream stability without methanation reaction, even at a steam-to-CO ratio as low as 0.8. The combination of Ni and Sn supported on FeCeOx led to a large lattice strain, the formation of NiSn alloy, and a strong synergistic effect between the bimetallic NiSn and FeCeOx mixed oxide support interface. All these features are very important in achieving the best activity and stability of NiSn/FeCeOx in the HT-WGS reaction.

Concentration of rare earth elements in the Faixa Placha tin deposit, Pedra Branca A-Type Granitic Massif, central Brazil, and its potential for ion-adsorption-type REE-Y mineralization

The Goiás Tin Province (GTP) in Brazil has great potential for rare earth elements (REE) deposits associated with A-type granites, such as the Pedra Branca Massif, which contains several Sn deposits and REE anomalies, hosted in its cupola and fracture greisens. The Faixa Placha is the most important tin deposit in the Pedra Branca Massif and has high REE-Y concentrations, both in the Sn ore and parent biotite granite, as well as greisenized granites and greisens, with the potential to be economically used as a byproduct of tin. The values exceed 1000 ppm in light rare earth elements (LREEs) and 500 ppm in heavy rare earth elements (HREEs) + Y in the parent granite. REE concentrations in greisenized granites and greisens are similar to that of the parent granite, indicating that the enrichment in REE is due to the presence of REE-bearing primary minerals and that greisenization did not affect the original magmatic primary REE content. The REE-bearing minerals in the parent granite are allanite, monazite, xenotime, thorite, apatite, and zircon. These minerals, except zircon, are altered to secondary monazite, silicates, fluorcarbonates, and oxyfluorides, which are responsible for the concentration of REE in greisenized granites and greisens and the availability of these metals for the clay fraction of saprolites and soils. Ion exchange analyses in the saprolites and soils of a Faixa Placha profile show that the extractions in the clay fraction are more enriched in REE-Y compared to the whole soil extractions, with values between 3425 and 36,762 ppm and between 2804 and 21,689 ppm, respectively. The REEs are more enriched in the basal part of the profile, especially the LREEs. These exchangeable REE-Y concentrations indicate the potential of the Faixa Placha and nearby areas to constitute an important REE-Y deposit of the ion-adsorption-type.