Microscopic Grains Research Articles

A framework for microscopic grains segmentation and Classification for Minerals Recognition using hybrid features

A framework for microscopic grains segmentation and Classification for Minerals Recognition using hybrid features

Influence of process parameters on the organization and properties of 316L-SCBCC bracket formed by selective zone laser melting

Abstract 316L porous skeletal scaffolds prepared by selective laser melting (SLM) technology are currently widely used in bone injuries. Its successful implantation is predicated on having properties that match those of natural bone. The process parameters significantly influence the performance of SLM-316L porous scaffold. In this study, the nine-group shaping process parameters were determined by orthogonal method. The 316L porous scaffolds were tested in compression, electrochemistry, XRD and microstructure. The influence of process parameters on the performance of body-centered cubic peripheral square structure bracket was investigated. The influence laws of process parameters on microstructure, mechanical properties and corrosion resistance were obtained. The results show that process parameters have a significant effect on the microstructure, properties and defect distribution. The reduction of defects and grain refinement in the stent is conducive to the improvement of compressive properties and hardness of the stent. The magnitude of the hardness is inversely related to the grain size. The corrosion current density of porous scaffolds are also affected by their microscopic defects and grain size. At an energy density of 78.70 J mm−3 presents the least defects and obtains smaller grains, resulting in the best mechanical properties and corrosion resistance.

Influence of electrodeposition parameters on the fabrication of Ni–Co/SiC + TiN composite films through pulse current electrodeposition

In this investigation, pulsed current electro-deposition (PCE) was used to prefabricate Ni–Co/SiC + TiN composite coatings (NCSTCCs) on mild steel surfaces. The research focused on the influence of two electrodeposition parameters, pulse frequency (PF) and duty cycle (DC), on NCSTCF features including microscopic surface morphology, crystal orientation, grain size, microhardness, SiC and TiN nanoparticles (NPs), deposition quantity, and corrosion resistance properties. The results indicated that NCSTCCs produced under a 10% DC showed minimal SiC and TiN contents with a percent volume of just 5.6 v/v% and 5.4 v/v% respectively under the fixed condition of 60 Hz PF. However, the three-dimensional surface diagram indicated that the Ni–Co/SiC + TiN composite film deposited at 50% DC and 10 Hz PF displayed the highest SiC and TiN contents (11.6 v/v% and 11.7 v/v%) among all the films. Furthermore, NCSTCCs deposited under 50% DC and 10 Hz PF had peak microhardness at 667.4 kg/mm2, while the composite film achieved a microhardness of 514.1 kg/mm2 when prepared using 10% DC and 60 Hz PF. Moreover, when the DC and PF were at 50% and 10 Hz respectively, the Ni–Co/SiC + TiN composite film presented the maximum charge transfer resistance (4915.7–4927.2 Ω·cm2), indicating an excellent corrosion resistance.

More microscopic interfacial segregation slowers macroscopic grain growth: A case in WC-Co cemented carbides

In industrial practice, combining grain growth inhibitors (GGIs) with low carbon content effectively restrains WC grain growth in WC-Co cemented carbides. However, the intricate relationship between carbon content, WC grain microstructure, and GGI impact remains unresolved. This study investigates two WC-Co sample sets, maintaining constant VC inhibitor levels but varying carbon content near upper (HC) and lower (LC) limits. SEM analysis revealed distinct morphologies: HC displayed truncated prism shapes, exposing long basal and prismatic terraces, while LC exhibited a saw-tooth morphology with finer grains. EBSD stereology quantified anisotropic WC grain growth, revealing suppressed growth perpendicular to both basal (HC: 0.51 μm vs. LC: 0.38 μm) and prismatic planes (HC: 0.44 μm vs. LC: 0.37 μm) with decreased carbon content. Atomic-resolution EDS showed higher V solute excess in LC at WC(basal)-Co, WC(prismatic)-Co interfaces, and step corners (HC: 4.6, 0.9, and 4.4 atoms/nm2; LC: 5.5, 0.9, and 7.8 atoms/nm2). Our findings elucidate a clear physical understanding that a low carbon content enhances V atom solubility within liquid cobalt, increasing the thickness of complexions to quad-layer on WC (basal)-Co interfaces and forming V-rich nanoprecipitates at step corners. Those inhibitory effects further limited step flow, resulting in pronounced step bunching and a saw-tooth fine-grained morphology in LC sample. This study highlights that complexions housing more inhibitory solute elements exert a stronger drag effect on grain growth front migration. This approach has the potential for studying grain growth in anisotropic materials, highlighting the importance of constructing experimental complexion diagrams in engineering fine-structured ceramics and metals.

Dynamic Shear Mechanical Properties and Microscopic Deformation Characteristics of Laser Cladding IN625 Alloy

To reveal the dynamic shear mechanical properties of laser cladding Inconel 625 (IN625) alloy, dynamic shear mechanical properties experiments are conducted on forged specimens and laser cladding specimens by split Hopkinson press bar experimental device. Optical microscopy, scanning electron microscopy, and electron backscattered diffraction (EBSD) are used to characterize the microscopic morphology, crystal orientation, and grain size of laser cladding specimens before and after dynamic shear deformation. In the results, it is shown that the yield strength and shear strength of both forged and laser clad specimens increase with the increase of shear strain rate, reflecting a remarkable strain‐rate‐strengthening effect, and the shear strength of the laser cladding specimen is higher than that of the forged specimen. After dynamic shear loading, the grains in the shear region of the laser cladding specimen are severely deformed, deformation bands appear, and some dendrites are transformed into equiaxed crystal. After shear deformation, the preferred orientation strength of the crystal increases, the small‐size grain and low‐angle grain boundary increase, and a large number of dislocations are formed in the shear region, which dominates the dynamic shear deformation behavior of the material. Dislocation is an important dominant mechanism of dynamic shear deformation.

Mechanism of grain refinement in FSW joints of 6063-T6 aluminum alloy under different rotational speeds

Abstract The inherent properties of aluminum alloys often result in defects like deformation and porosity in joints and welds created through conventional fusion welding. Our paper investigates the impact of varying rotational speeds in the friction stir welding of 4mm thick 6063-T6 aluminum alloy, focusing on microscopic grain refinement and mechanical property alterations in T-joints. Using mechanical stretching and numerical simulation methods, we observed that the initial weld joint is robust, with minimal flying edges and a distinct fish-scale pattern on the surface. Moreover, the grain sizes in the weld’s core area are notably smaller than those in the region affected by the upper axial shoulder. The mechanical properties of the joint experienced a first increase and then a decrease in mechanical properties when the friction stir welding rotational speed, was increased from 600r/min to 1500r/min. Moreover, in 1000r/min rotational speed, the material welded tensile strength and yield strength of the best tensile strength compared to the raw material to enhance the 21MPa, yield strength of 30MPa, elongation close to the raw material of 89.86%.

Multi scale simulation of crack propagation in polycrystalline SiC

Silicon carbide (SiC) is considered one of the most promising emerging materials in the fields of refractory materials and semiconductors. In this paper, a multi-scale numerical simulation method is proposed to investigate crack propagation in SiC at different scales, using a combination of cohesive zone model and molecular dynamics (MD). The microstructure of the material is represented by Voronoi subdivision, and bilinear treatment is applied at the grain boundaries. Firstly, MD models with different microscopic defects were established to obtain the corresponding traction separation curves. Then, the element parameters, obtained by fitting the traction separation law, were inserted into the cohesive elements located at the grain boundary and within the grain. Finally, the finite element models were simulated by the failure criterion. The fracture toughness of the material is predicted, and the influence of microscopic defects and grain distribution on macroscopic fracture toughness is explored. The results indicate that the grain distribution and the type of micro defect have an impact on the crack growth path and macro fracture toughness. The simulation results are consistent with published experimental results, which demonstrates the viability of employing this multi-scale analysis method for examining and replicating the micro-, meso-, and macro-scale crack propagation characteristics of SiC.

Semisupervised Boundary Detection for Aluminum Grains Combined With Transfer Learning and Region Growing.

In the manufacturing process of aluminum alloy, the size, distribution, and shape of microscopic grains indicate the mechanical characteristics and product quality. However, for metallographic images that can reveal microstructures, the cost of expert labeling at pixel level is high. To solve the problem, we propose a semisupervised learning strategy for grain boundary detection with a few labeled images and abundant unlabeled samples. To expand the helpful information, transfer learning and rule-based region growing are considered. Specifically, a deep network used for extracting multiscale features is designed. With constant training, through a few labeled metallographic images and abundant transferred natural images, pseudo annotations are generated gradually for unlabeled metallographic images iteratively by feature similarity and boundary region growing. The increased unlabeled samples with their pseudo annotations would be involved in the following training process in semisupervised self-training mode to improve the generalization ability of model, together with the domain adaptation block. In experiments, the proposed two methods named semiricher convolutional features-generative adversarial networks (SemiRCF-GAN) and semiricher convolutional features-maximum mean discrepancy (SemiRCF-MMD) can effectively detect grain boundaries with only one labeled metallographic image, and achieve F1 scores of 0.73 and 0.72, respectively, which surpass typical methods.

Nanoscale Characterization of Photocurrent and Photovoltage in Polycrystalline Solar Cells.

We investigate the role of grain structures in nanoscale carrier dynamics of polycrystalline solar cells. By using Kelvin probe force microscopy (KPFM) and near-field scanning photocurrent microscopy (NSPM) techniques, we characterize nanoscopic photovoltage and photocurrent patterns of inorganic CdTe and organic-inorganic hybrid perovskite solar cells. For CdTe solar cells, we analyze the nanoscale electric power patterns that are created by correlating nanoscale photovoltage and photocurrent maps on the same location. Distinct relations between the sample preparation conditions and the nanoscale photovoltaic properties of microscopic CdTe grain structures are observed. The same techniques are applied for characterization of a perovskite solar cell. It is found that a moderate amount of PbI2 near grain boundaries leads to the enhanced photogenerated carrier collections at grain boundaries. Finally, the capabilities and the limitations of the nanoscale techniques are discussed.

Localized Bound Multiexcitons in Engineered Quasi-2D Perovskites Grains at Room Temperature for Efficient Lasers.

Reducing the excitation threshold to minimize the Joule heating is critical for the realization of perovskite laser diodes. Although bound excitons are promising for low threshold laser, how to generate them at room temperature for laser applications is still unclear in quasi-2D perovskite-based devices. In this work, via engineering quasi-2D perovskite PEA2 (CH3 NH3 )n -1 Pbn Br3 n +1 microscopic grains by the anti-solvent method, room-temperature multiexciton radiative recombination is successfully demonstrated at a remarkably low pump density of 0.97 µJ cm-2 , which is only one-fourth of that required in 2D CdSe nanosheets. In addition, the well-defined translational momentum in quasi-2D perovskite grains can restrict the Auger recombination which is detrimental to radiative emission. Furthermore, the quasi-2D perovskite grains are favorable for increasing binding energies of excitons and biexcitons and so as the related radiative recombination. Consequently, the prepared <n= 8> phase quasi-2D perovskite film renders a threshold of room-temperature stimulated emission as low as 13.7 µJ cm-2 , reduced by 58.6% relative to the amorphous counterpart with larger grains. The findings in this work are expected to facilitate the development of solution-processable perovskite multiexcitonic laser diodes.

Experimental Research on the Surface Quality of Milling Contour Bevel Gears

Contour bevel gears have the advantages of high coincidence, low noise and large bearing capacity, which are widely used in automobile manufacturing, shipbuilding and construction machinery. However, when the surface quality is poor, the effective contact area between the gear mating surfaces decreases, affecting the stability of the fit and thus the transmission accuracy, so it is of great significance to optimize the surface quality of the contour bevel gear. This paper firstly analyzes the formation process of machined surface roughness of contour bevel gears on the basis of generating machining method, and dry milling experiments of contour bevel gears are conducted to analyze the effects of cutting speed and feed rate on the machined surface roughness and surface topography of the workpiece. Then, the surface defects on the machined surface of the workpiece are studied by SEM, and the causes of the surface defects are analyzed by EDS. After that, XRD is used to compare the microscopic grains of the machined surface and the substrate material for diffraction peak analysis, and the effect of cutting parameters on the microhardness of the workpiece machined surface is investigated by work hardening experiment. The research results are of great significance for improving the machining accuracy of contour bevel gears, reducing friction losses and improving transmission efficiency.

Toward low-salinity waterflooding predictive capability development in carbonates for fast screening of oil-brine-rock candidates

Despite numerous studies on the low-salinity waterflooding (LSWF) technique, a robust predictive capability has not yet been established. Predictive capability development is essential to reduce costs and time during the early screening or prioritization of candidate fields for LSWF in the opportunity realization process (ORP). This study aims at proposing a set of screening methods that offer the best LSWF predictive capability for various crude oil-brine-carbonate rock systems. In this regard, the robustness of different methods for predicting oil recovery factor (RF) from core-scale spontaneous imbibition (SI) experiments in carbonate rocks was investigated here. The relevant small-scale screening methods were divided into two distinct categories. The first category includes methods based on rock/fluid interactions: wettability assessment based on flotation and contact angle measurement, and geochemical assessment to identify mineral dissolution (and pH change). The second group includes methods based on probing fluid/fluid interactions: oil-brine interfacial tension (IFT) and viscoelasticity, and micro-dispersion formation. The most common types of carbonate rocks, including dolomite, limestone, and chalk, were used to comprehensively evaluate the response of each carbonate rock type to brines of different salinities. Each rock type could be distinguished with its particular microscopic texture, pore-size, grain type, and carbonate mineral structure. According to the SI results, oil recovery strongly depends not only on brine salinity but also on the rock type. The oil RF for Indiana limestone was found to be higher than that for other rock types but showed less sensitivity to the degree of dilution. Additionally, RF from dolomite and chalk plugs showed the most and the least sensitivity to the degree of brine dilution, respectively. We introduced a brine efficiency index based on the SI results to compare the results for different rock types and salinities. The results of the systematic tests performed here showed that variation of IFT and viscoelasticity (expressed as phase angle) with brine salinity reduction was neither significant nor monotonic, and did not correlate with the brine efficiency index. Also, minor/negligible mineral dissolution was observed upon brine-rock contact. On the other hand, wettability results based on contact angle measurement and flotation, as well as microdispersion results strongly correlated with the brine efficiency index over a wide range of brine salinities, which indicates these techniques can quickly predict the potency of a system toward low salinity effect (LSE). It is hypothesized, therefore, that the techniques which involve rock explicitly would be more robust because they capture the rock-type dependency of LSE too. The findings from this study can be used for quick screening of the candidate formations for LSWF, before performing the costly and time-intensive special core analysis (SCAL) experiments. The data provided by this research can also enrich the SCAL data bank toward developing robust data-driven predictive models.

Proximal composition of bee pollen and its functional effect on stress

Bee pollen is an agglomerate of microscopic grains rich in proteins and phenolic compounds. Other products rich in flavonoids and vitamins, as well as bee pollen, have been shown a positive effect on stress, which is a physical condition that can lead to several somatic disorders. In this work the compositional characteristics of bee pollen were measured, and its effect in volunteers’ adult men was evaluated by a cortisol salivary test, and by responding to Lip’s Stress Symptom Inventory. The volunteers were given bee pollen for a month. After that, the salivary cortisol was measured and applied the questionnaire. Bee pollen shown an adequate nutritional composition. Its administration had a 23% reduction in salivary cortisol. The values obtained in the questionnaire were consistent with the results of the cortisol dosage, which relieved the symptoms reported by the volunteers. A phytochemical screening was also performed on this material showing the presence of flavonoids, which may be an active compound responsible for the functional effect in the stress relieving of the participants.

Determination of Atomic-Scale Density of Materials from Total Scattering Profiles

Atomic-scale density (microscopic density) for non-crystalline materials is sometimes hard to obtain when the sample contains microscopic grains and/or pores. This is also the case for crystalline materials that contain atomic scale defects. We propose a method for the determination of the microscopic density of an amorphous sample from total scattering data. Theoretically, the microscopic density can be calculated from the slope of the pair distribution function G(r) in the short-distance region from zero to the nearest neighbor. However, the observed G(r) in this region is greatly affected by unphysical modulation of the experimental scattering data and the derived structure factor S(Q). As a result, the estimated microscopic density has a large uncertainty. The proposed method removes the unphysical modulation of S(Q) and obtains a G(r) that satisfies theoretical conditions only using the coherent scattering intensity and the first neighbor distance. We have applied the present method to SiO2 glass, crystalline Ni powders, and a set of data from germinate glasses whose densities have been reported. The results of the present method are consistent with the reported values within ±5%.

Strength estimation of granular rocks using a microstructure-based empirical model

A natural rock is an assembly of various mineral grains, and the microscopic grain structure of the rock influences its strength. The strength of granular rocks can be related to microscopic grain structure; however, empirical models linking microscopic grain structure and rock strength are rarely reported. This research presents a characterization method for geometric heterogeneity induced by the grain size difference. The heterogeneity of the microscopic scanning images of a coarse-grained marble is analyzed using a proposed heterogeneity index. A microstructure-based empirical model is proposed to describe the relation between the compressive strength of rock and its micro-property parameters. This microstructure-based empirical model is verified using numerical and experimental test data. The analysis results show that the proposed model can predict the strength of a granular rock better than existing models of similar nature. The model parameters for different rocks such as LdB granite, Aminadav dolomite, and Bohemian Massif granite are obtained by nonlinearregressionanalysis. This model is also employed to predict crack initiation and damage stresses of rocks, showing results in good agreement with the experimental data.

Slow Neutron-Capture Process: Low-Mass Asymptotic Giant Branch Stars and Presolar Silicon Carbide Grains

Presolar grains are microscopic dust grains that formed in the stellar winds or explosions of ancient stars that died before the formation of the solar system. The majority (~90% in number) of presolar silicon carbide (SiC) grains, including types mainstream (MS), Y, and Z, came from low-mass C-rich asymptotic giant branch (AGB) stars, which is supported by the ubiquitous presence of SiC dust observed in the circumstellar envelope of AGB stars and the signatures of slow neutron-capture process preserved in these grains. Here, we review the status of isotope studies of presolar AGB SiC grains with an emphasis on heavy element isotopes and highlight the importance of presolar grain studies for nuclear astrophysics. We discuss the sensitives of different types of nuclei to varying AGB stellar parameters and how their abundances in presolar AGB SiC grains can be used to provide independent, detailed constraints on stellar parameters, including 13C formation, stellar temperature, and nuclear reaction rates.

New Polarimetric Data for the Galilean Satellites: Europa Observations and Modeling

This paper is dedicated to a long-standing problem of the shape of the negative branch of polarization (NBP) for Jupiter's moon Europa, determination of which is crucial for the characterization of the icy regolith on this satellite and similar objects, as well as for further progress in understanding light scattering by particulate surfaces. To establish the shape of Europa's NBP, in 2018–2021 we accomplished high-precision disk-integrated polarimetry of Europa in the UBVR I bands using the identical two-channel photoelectric polarimeters mounted on the 2.6 m Shajn reflector of the Crimean Astrophysical Observatory and the 2 m telescope of the Peak Terskol Observatory. We found that the polarization dependence on the phase angle in each filter is an asymmetric curve with a sharp polarization minimum at phase angle , after which the polarization degree gradually increases to positive values, passing the inversion angle at α inv ≈ 6° − 7°. Within the error limits, the parameters P min, , and α inv of the NPB are independent of the wavelength in the visible spectrum. The polarization curve clearly demonstrates the so-called polarization opposition effect (POE). Our analysis of the previous and new polarimetric observations of Europa allows us to conclude that the POE is caused by coherent backscattering of sunlight on microscopic icy grains covering Europa’s surface. Computer modeling with the numerical radiative transfer coherent backscattering method demonstrates that the best fit to the polarimetric observations and geometric albedo of Europa is provided by a regolith layer of elementary single-scattering albedo ∼0.985 and extinction mean free path length 2π l/λ eff ≈ 150, λ eff representing the effective wavelength in the UBVR I spectral bands.

Nature and genesis of the Zaglic Au deposit, NW Iran: Constraints from geochemical studies

The Zaglic Au deposit is located in a Late Oligocene magmatic arc within the Arasbaran Magmatic Belt of NW Iran, which formed during the subduction of Mesotethys oceanic crust. Country rocks comprise intermediate to mafic volcanic and volcanoclastics of andesitic to trachy–andesitic composition, and exhibit late granite plutonism. Host assemblages display medium– to high–K calc–alkaline affinities with fractionated REE profiles, including Nb and Ti depletion and Rb, Ba, Th, U enrichment, consistent with subducted terranes. Wall–rock alteration comprises multi–stage silicic, sericitic, argillic and/or propylitic domains, associated with (i) pre–, (ii) main–, and (iii) post–ore emplacement. Pyrite is the dominant sulfide with spatially associated chalcopyrite and bornite in quartz vein and veinlets, with free gold occurring as microscopic grains in quartz, or as inclusions in pyrite. Fluid inclusion analysis of pre– (quartz I), main– (quartz II) and post–ore stages (quartz III) identifies liquid–rich, multi–stage, and vapor–rich varieties with decreasing temperatures and salinities, with the following Th and NaCl wt% equivalent ranges: pre–mineralization: 230–382 °C and 6.1–8.2; main–ore: 179–311 °C and 0.35–3.22%; and post–ore: 150–195 °C and 2.2–2.9%. Stable isotope analysis identifies variable δ18Ofluid and δDfluid signatures, including: quartz I: 2–3.4‰; −86 to −78‰; quartz II: −0.6–0.2‰; −89 to −85‰; sericite: −0.2 to 3.4‰; −107 to −91‰; and chlorite: −0.6 to 1.4‰; −115 to −104‰. Such ranges imply a mixture of magmatic and meteoric fluids, characteristic of a wide range of epithermal Au deposits. Sulfur isotope composition (δ34S) of this deposit's two principal sulfide minerals is consistent with compositionally reduced mineralizing fluids including: pyrite: −1.4 to 2.7‰ and chalcopyrite: −2.6 to 1.8‰. Geochronological analysis records 40Ar/39Ar dating of biotite from andesite porphyry with a plateau Eocene age of 48.20 ± 0.73 Ma, together with ~8 Ma or Late Miocene ages from fine–grained sericite.

Octahedral distortion-driven phase transition, relaxation and conduction process of Zr/Sn modified barium titanate relaxors

This paper mainly reports the effect of Zr/Sn substitution on structural, dielectric, and electrical characteristics of pure BaTiO3 (BT). The addition of Zr4+ and Sn4+ at the Ti-site of BT has bas created compositional disordered state. The disordered state is the necessary/prerequisite for the development of the relaxor ferroelectrics. The appearance of polar nano-regions is the cause of the relaxor property of the ferroelectric. The dielectric characteristics of Ba(ZrTi)O3 (BZT) and Ba(SrTi)O3 (BST) deviate from those of traditional Curie Weiss law, and hence do not show a sharp phase transition, but little diffused as compared to that of BT. Impedance spectra is fitted to the modified Cole-Cole equation to reveal the (i) asymmetry and broadening of the dielectric/impedance dispersion curves, (ii) non-Debye type of relaxation, (iii) actual grain and grain boundary contributions and (iv) semiconductor or positive temperature coefficient of resistance (PTCR) nature of the prepared materials. The correlated barrier hopping model fits well to BT and BST, whereas overlapping polaron tunnelling and small polaron tunnelling models signify the conduction mechanism of BZT. Zr and Sn addition increases impedance, energy storage and decreases the conductivity, leakage current and loss energy of BT. The high energy efficiency, good temperature stability of energy efficiency, high recoverable energy density and high breakdown strength of BZT and BST is observed as compared to those of BT which satisfy their the energy storage applications. The relaxation phenomena and the connection of microscopic electrical grain and grain boundary with microstructure are discussed here.

Characterization of synthetic and natural gold chalcogenides by electron microprobe analysis, X‐ray powder diffraction, and Raman spectroscopic methods

AbstractElectron microprobe analysis (EMPA), X‐ray powder diffraction (XRD), and Raman spectroscopy (RS) were applied to characterize the synthetic gold chalcogenides of the Au–Te–Se–S system and natural analogs from the Gaching deposit (Central Kamchatka, Russia). The EPMA results showed that the synthetic chalcogenides have different Te/Se/S and Au/X (X = Te + Se + S) ratios: AuX2, Au3X10, and AuX. They are similar in composition to natural compounds — calaverite (AuTe2), maletoyvayamite (Au3Te6Se4), and unnamed minerals AuTe0.7Se0.3 and AuSe0.7S0.3. It was established that chalcogenides AuX, Au3X10, and AuX2 have a specific Raman spectra with characteristic peaks. The position of the peaks and the character of the spectra of the synthetic phases and their natural analogs from the Gaching deposit coincide within the limits of accuracy. Different ratios of chalcogenes Te/Se/S in compounds influence the Raman peak positions. The positions of the peaks for natural compounds AuX differ depending on the predominance of Te (AuTe0.7Se0.3) or Se (AuSe0.7S0.3). AuSe synthetic phases consist of a mixture of α‐ and β‐polymorphs. Raman spectroscopy can be used for the identification of natural gold chalcogenides worldwide, which are difficult to diagnose by other methods due to the microscopic grain sizes and close intergrowths with other ore minerals. The similarity of the Raman spectra upon changing the concentrations of Se and S suggests identical structures and possible isomorphism in the composition range of AuTe0.7Se0.3– AuTe0.7Se0.2S0.1, AuTe1.9Se0.1– AuTe1.8Se0.1S0.1, and Au3Te6Se4– Au3Te6S3Se.