Search Results (910)

The flotation effect of the new collector, 2-octylthio(aniline) (2-OA), on two types of sulfide ores under various conditions was investigated and compared with that of the conventional collector, potassium amyl xanthate (PAX). Collector 2-OA showed better floatability in copper sulfide ore flotation, and the copper grade could be enriched up to 1.5 times the original ore during the secondary flotation of copper sulfide ore. Compared to PAX, 2-OA demonstrated a stronger ability to collect copper than iron. Furthermore, in the flotation of gold sulfide ore, a 13% higher gold recovery was achieved with 2-OA than with PAX. Surface chemical analysis showed that 2-OA altered the surface charge of minerals and formed Cu–S and Cu–N bonds on the chalcopyrite surface. The adsorption capacity of 2-OA exceeded that of PAX, thereby enhancing the flotation effect. Overall, 2-OA exhibits better flotation performance and potentially serves as an efficient collector for sulfide ore flotation. Full article

The Axi gold deposit, a low-sulfidation epithermal deposit in the Western Tianshan, China, hosts over 50 t of gold resources and is widely regarded as the result of coupled processes of rock deformation, heat transfer, pore fluid flow, and chemical reactions. However, research on the ore-forming processes of this gold deposit from a coupled perspective remains limited, resulting in its ore-forming mechanisms being incompletely understood. In this paper, we use the concept of mineralization rate based on computational modeling to indicate the 3D spatial distribution of mineralization. The simulation results reveal the following: (1) temperature gradients play a key role in influencing mineral precipitation, whereas the effect of pore fluid pressure gradients is relatively negligible; (2) gold precipitation, characterized by a negative mineralization rate, predominantly took place along fault zones that exhibit vertical transitions from steep to gentle slopes or lateral bends, which are further distinguished by the accumulation of fluids and the presence of significant temperature gradients. Notably, this particular distribution pattern of gold precipitation closely mirrors the spatial arrangement of known gold orebodies. These findings suggest that the coupling of multiple physical and chemical processes at specific fault sites plays a critical role in ore formation, providing new insights into the mechanisms governing the development of the Axi gold deposit. Furthermore, based on these observations, it can be inferred that the deeper regions of the Axi gold deposit hold considerable mineralization potential. Full article

The mechanisms of massive gold migration and enrichment are challenging issues in mineral deposit research. The evolution of the elements and structures of gold-bearing minerals is the key to revealing the mechanisms of gold enrichment and migration. The Sawayardun gold deposit has an ore reserve of 127 t located in the southwestern Tianshan, Xinjiang, China. It is an ideal place for studying the mechanisms of massive gold migration and precipitation. However, the occurrence and distribution of gold are unclear, preventing an understanding of the massive gold enrichment and precipitation mechanism in the Sawayardun gold deposit. Therefore, in this study, the microscopic structural characteristics and chemical compositions of sulfides and gold minerals in the deposit were comprehensively analyzed using scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) techniques. The mineralization evolution is divided into a metamorphosed sedimentary period and a hydrothermal mineralization period, with the latter further subdivided into four mineralization stages: the quartz–pyrite stage, the arsenopyrite–pyrite stage, the polymetallic sulfide stage, and the carbonate stage. EPMA analysis reveals no clear compositional trends among different pyrite generations. Arsenopyrite (Apy) is more enriched in Au and Sb than pyrite. Overall, arsenopyrite is S-rich and As-deficient. Compared to Apy2, Apy1 is enriched in Fe and S but depleted in As. Stibnite is closely associated with native gold and contains elevated Au (up to 3.63%). Invisible gold exists in a form that is visible at the micrometer-to-atomic scale within pyrite and is lattice-bound in arsenopyrite. Visible gold occurs as native grains in quartz fractures or within sulfides. The composition of pyrite indicates that the Sawayardun gold deposit formed in a reducing, medium-depth, meso-epithermal environment. Au extraction by Sb-rich melts, dissolution–reprecipitation, and adsorption by As-bearing pyrite were the primary mechanisms for Au migration and precipitation. This study contributes to understanding the enrichment and precipitation processes of gold in orogenic-gold deposits in southwestern Tianshan. Full article

The iron-oxide-copper-gold (IOCG) skarns of the Tatatila-Las Minas mining district in central Mexico represent a structurally-controlled, exhumed fossil geothermal system located in the eastern sector of the Trans-Mexican Volcanic Belt (TMVB). The district was historically exploited for gold and copper mineralization. The emplacement of the ore bodies was controlled by regional Neogene–Quaternary NE- and NW-striking fault systems formed during the extensional evolution of the TMVB. These faults acted as conduits for high-temperature hydrothermal fluids circulating during the cooling of the Neogene magmatic intrusions. By integrating detailed field study with available exploration borehole data, the spatial distribution of the skarn bodies was reconstructed. Three main emplacement geometries were identified: (a) at contacts between magmatic bodies and host rocks, (b) as lenticular or irregular bodies parallel to the host rock foliation, and (c) at the intersections of near-orthogonal faults. Although structural controls on skarn formation represent a key factor in ore emplacement, their analysis remains scarcely explored. This paper therefore contributes to filling this gap by providing a detailed characterization of the structural framework governing IOCG skarn development at Tatatila–Las Minas. The results improve understanding of IOCG systems formation and provide predictive criteria for mineral exploration in similar geological settings, potentially reducing exploration and mining risks. Full article

While artisanal gold mining (AGM) has been credited as a sector that sustains many households in Zimbabwe, it has at the same time been criticized as the chief driver of ecological degradation and social vulnerability. This study qualitatively examines the environmental and socioeconomic impacts of AGM by conducting in-depth interviews with miners, residents, and policymakers across six central mining districts. The study findings indicate that the use of mercury has resulted in severe contamination of water bodies, while clearing land to pave the way for mining has led to severe deforestation, loss of biodiversity, and declining agricultural productivity due to the loss of fertile soils. It was also found that most AGMs were unregulated, and their unregulated operations have intensified health risks, social inequality, and land-use conflicts with the local community. This study provides an insight into how dependence on AGM has perpetuated a cycle of ecological degradation and poverty among many Zimbabweans. The study, therefore, attempts to combine community narratives with policy analysis, thereby proposing a framework for sustainable AGM in Zimbabwe. This involves advocating for the use of environmentally friendly technologies and promoting participatory environmental governance among all key stakeholders. The study contributes to achieving a balance between economic benefits and environmental management by advancing the discourse on sustainable development and community resilience in resource-dependent economies. Full article

Hair mineral analysis (HMA) has emerged as a promising non-invasive method for assessing long-term exposure to trace elements and metals, potentially complementing traditional biochemical and clinical markers of cardiovascular risk. This review synthesizes current evidence on the relationships between hair elemental profiles and cardiovascular disease (CVD), with an emphasis on toxic metals (As, Hg, Pb, Cd, Ni, Al) and essential micronutrients (Mg, Mn, Zn, Cu, Fe, Cr, Li). The reviewed studies consistently show that patients with CVD exhibit elevated levels of toxic elements and reduced concentrations of protective ones, reflecting oxidative stress, inflammation, and endothelial dysfunction as mechanistic links. Methodologically, the review highlights inductively coupled plasma mass spectrometry (ICP-MS) with collision/reaction cell technology and microwave digestion as gold-standard analytical approaches, while underscoring the urgent need for harmonized protocols, validated washing procedures, and certified reference materials. The interpretation of HMA requires consideration of temporal dynamics, external contamination, and regional variability. Although current evidence supports the research utility of HMA, its clinical integration remains limited by the absence of reference ranges and prospective validation. HMA may hold future value in environmental risk stratification and primary prevention in exposed populations, but further standardization and large-scale longitudinal studies are necessary to define its diagnostic and prognostic relevance in cardiovascular medicine. Full article

The Hadamengou gold deposit, located on the northern margin of the North China Craton, represents one of the region‘s most significant gold mineralization clusters. However, exploration in its deeper and peripheral sectors is constrained by ecological protection policies and the structural complexity of the ore-forming systems. Multivariate analysis combined with multi-model integration provides an effective mathematical approach for interpretating geochemical datasets and guiding mineral exploration, yet, its application in the Hadamengou region has not been systematically investigated. To address this research gap, this study developed a pilot framework in the key Buerhantu area, on the periphery of the Hadamengou metallogenic cluster, applying and adapting a multivariate-multimodel methodology for mineral prediction. The goal is to improve exploration targeting, particularly for concealed and deep-seated mineralization, while addressing the methodological challenges of mathematical modeling in complex geological conditions. Using 1:10,000-scale lithogeochemical data, we implemented a three-step workflow. First, isometric log-ratio (ILR) and centered log-ratio (CLR) transformations were compared to optimize data preprocessing, with a reference column (YD) added to overcome ILR constraints. Second, principal component analysis (PCA) identified a metallogenic element association (Sb-As-Sn-Au-Ag-Cu-Pb-Mo-W-Bi) consistent with district-scale mineralization patterns. Third, S-A multifractal modeling of factor scores (F1–F4) effectively separated noise, background, and anomalies, producing refined geochemical maps. Compared with conventional inverse distance weighting (IDW), the S-A model enhanced anomaly delineation and exploration targeting. Five anomalous zones (AP01–AP05) were identified. Drilling at AP01 confirmed the presence of deep gold mineralization, and the remaining anomalies are recommended for surface verification. This study demonstrates the utility of S-A multifractal modeling for geochemical anomaly detection and its effectiveness in defining exploration targets and improving exploration efficiency in underexplored areas of the Hadamengou district. Full article

We present an integrated methodology for three-dimensional inversion of large-scale airborne electromagnetic (AEM) and magnetic survey data that simultaneously recovers electrical conductivity, chargeability, and both induced and remanent magnetizations. A central feature of the AEM component is the explicit incorporation of induced polarization (IP) effects. Neglecting IP responses can lead to biased conductivity models, particularly in mineralized systems where disseminated sulfides contribute strongly to chargeability. Using the Generalized Effective-Medium Theory of Induced Polarization (GEMTIP), the inversion produces physically consistent 3D distributions of conductivity and chargeability. To enhance magnetic interpretation, we also implement a vector magnetic inversion that resolves both induced and remanent magnetization from Total Magnetic Intensity (TMI) data, enabling geologically realistic magnetization models in terranes with significant remanence. This integrated workflow was applied to airborne AEM and TMI datasets collected over the Asankrangwa Gold Belt in central Ghana. The inversion results delineate a key exploration target defined by coincident magnetic low and elevated chargeability, interpreted as sulfide-rich gold mineralization and subsequently confirmed by drilling. These results demonstrate that jointly accounting for IP and remanent magnetization in 3D inversion substantially improves subsurface characterization and provides a powerful tool for mineral exploration in structurally and lithologically complex environments. Full article

Sb-rich avicennite (first discovery in Russia) was found at the Khokhoy gold deposit, 120 km west of Aldan, Aldan district, Republic of Sakha (Yakutia), Eastern Siberia, Russia. The mineral of critical metal thallium forms irregularly shaped grains up to 0.25 mm in size, in association with amgaite, weissbergite, goethite, gold, and unidentified Tl-bearing phases. Aggregates of colloform structure prevail, represented by rhythmic-, concentric-zonal, kidney-shaped, and spherulitic varieties. Avicennite is black in color, with metallic luster, and it fractures unevenly. No cleavage is observed. The density value of avicennite, obtained using its empirical formula and the unit cell parameters calculated from the powder X-ray diffraction data, is 8.548 g/cm³. In reflected light, avicennite is light gray and isotropic. Internal reflections are absent. Reflection is very low; the reflectivity curve is of mixed type with a small maximum in the blue part. Its chemical composition (average value on 10 analyses, wt.%): Tl₂O₃—85.36, V₂O₅—0.73, As₂O₅—0.85, Sb₂O₅—12.98, Total—99.92; It corresponds to the following empirical formula (calculation for three atoms of O): Tl_1.40Sb⁵⁺_0.30V⁵⁺_0.03As⁵⁺_0.03O₃. The unit cell parameters calculated from the powder X-ray diffraction data are as follows: the mineral is cubic, a = 10.496(6) Å, V = 1156(2) Å3. Full article

The Yixingzhai deposit is a giant gold system containing four cryptovolcanic breccia pipes, several of which host significant porphyry-type gold orebodies at depth. A key exploration target is the Tietangdong cryptovolcanic breccia pipe, characterized by skarn alteration in its upper zones. However, the evolution of early hydrothermal fluids and their implications for gold enrichment potential remain poorly understood. This study employs an integrated approach—combining petrography, electron probe microanalysis, laser ablation-inductively coupled plasma–mass spectrometry (LA-ICP-MS), and LA-ICP-MS elemental mapping—to analyze zoned garnets within the Tietangdong skarn, with the aim of deciphering changes in magmatic–hydrothermal composition and physicochemical conditions, as well as their influence on gold enrichment. Textural and compositional data reveal three distinct generations of garnets. Garnets from generations I and III consist of a grossular–andradite solid solution and commonly exhibits optical anisotropy. In contrast, generation II garnet is predominantly andraditic and optically homogeneous. LA-ICP-MS elemental mapping of generations I and III indicates that both generations contain significant Al and Fe, with their optical anisotropy attributed to a high degree of Fe³⁺/Al³⁺ cationic ordering. Compared to generations I and III, generation II garnet displays distinct geochemical characteristics, including enrichment in Fe, As, Sn, W, and U, patterns enriched in light rare earth elements, a positive Eu anomaly, and a wide range of Y/Ho ratios. Garnets from generations I and III crystallized under relatively high-pressure, high-temperature, and low-oxygen fugacity conditions, whereas generation II garnets formed under lower pressure–temperature conditions and higher oxygen fugacity. Moreover, concentrations of Co, Ni, and Cu increase systematically from generation I to generation III. We interpret the sharp compositional break at generation II as recording of the pulsed injection of magmatic–hydrothermal fluids, which enhanced the potential for gold mineralization. The zoning patterns in garnet provide a robust record of the temporal evolution of physicochemical conditions and fluid composition in the hydrothermal system. Full article

The traditional methods for classifying elemental concentrations such as the cumulative frequency method, the logarithmic interval method, and the mean–standard deviation method all have the limitation of depending on a specific dataset. An objective “ruler” that can measure the elemental concentration level regardless of the amount of data (even for a single sample) and enables comparisons among different elements and regions is highly necessary. Recently, the 19-level fixed-value method was proposed as a “ruler” to measure the elemental concentrations of Sn, Li, Mo, and Ni objectively and to facilitate comparisons across elements and regions. However, the method for Au has not been proposed until now. In this paper, we propose the “ruler” for Au, which objectively divides Au concentrations into 19 levels with 18 fixed values from the detection limit to the cut-off grade with easily understood numbers. The “ruler” for Au along with those for Mo and Sn was applied to geochemical survey data at 1:200,000 and 1:50,000 scales, respectively, in the Zhongchuan area of Western Qinling, China, to classify elemental concentrations and draw geochemical maps. The results show that elemental concentrations can be measured using the “ruler” to assess the background, anomaly, and mineralization levels objectively, and the levels can be compared across different elements, regions, and even different scales. Geochemical maps show that in the study area, known gold deposits are all associated with high anomalies or mineralization levels of Au, while the Mo and Sn concentrations are predominantly at background levels. These results are consistent with the known mineral resources in this area. When superimposing geochemical maps of larger scales onto those of smaller scales, the variation in the elemental concentration levels with different survey scales indicates valuable geochemical meanings for mineral exploration. Full article

Geological interfaces are crucial elements governing deposit formation, such as silica–calcium surfaces, intrusive contact interfaces, and unconformities can serve as key symbols for mineral exploration prediction. Geological maps provide relatively detailed representations of primary geological interfaces and their interrelationships. However, in previous mineral resource predictions, the type differences in different geological interfaces were ignored, and the types of different geological interfaces vary greatly, thus affecting the validity of the mineral prediction results. Manual interpretation and analysis of geological interfaces involve substantial workloads and make it difficult to effectively apply the rich geological information depicted on geological maps to mineral exploration prediction processes. Therefore, this study proposes a model for intelligent identification of geological interface types based on deep learning. The model extracts the attribute information, such as the age and lithology of the geological bodies on both sides of the geological boundary arc, based on the digital geological map of the Gouli gold mining area in Dulan County, Qinghai Province, China. The learning dataset comprising 5900 sets of geological interface types was constructed through manual annotation of geological interfaces. The arc segment is taken as the basic element; the model adopts natural language processing technology to conduct word vector embedding processing on the text attribute information of geological bodies on both sides of the geological interface. The processed embedding vectors are fed into the convolutional neural network (CNN) for training to generate the geological interface type recognition model. This method can effectively identify the type of geological interface, and the identification accuracy can reach 96.52%. Through quantitative analysis of the spatial relationship between different types of geological interfaces and ore points, it is known that they have a good correlation in spatial distribution. Experimental results show that the proposed method can effectively improve the accuracy and efficiency of geological interface recognition, and the accuracy of mineral prediction can be improved to some extent by adding geological interface type information in the process of mineral prediction. Full article

Background/Objectives: Dual-energy X-ray absorptiometry (DEXA), the gold standard for assessing bone mineral density (BMD), may yield inaccurate results in certain populations. This has prompted interest in alternative imaging methods, including the MRI-based cervical and lumbar vertebral bone quality (CVBQ and LVBQ) scores. The lumbar VBQ score is a validated MRI-based metric with excellent inter- and intra-rater reliability and established clinical utility in preoperative spine assessment, whereas the newer cervical VBQ (CVBQ) score has shown mixed results in early studies. This study investigates associations between a novel CVBQ score derived from MRI and established BMD metrics (Hounsfield unit (HU) measurements and DEXA values) to evaluate the comparative utility of these methods. Methods: A retrospective review was performed on patients who underwent cervical CT, DEXA, and non-contrast MRI of the cervical and lumbar spine between 2016 and 2022. BMD was assessed using DEXA T-scores, cervical HU measurements, and CVBQ and LVBQ scores derived from T1-weighted MRI sequences. Statistical comparisons between patients with and without osteoporosis were conducted using t-tests and Pearson correlation coefficients. Results: A total of 133 patients were included for CVBQ scoring and 127 for LVBQ. The CVBQ score showed poor correlation with both DEXA (r = −0.09, p < 0.001) and HU measurements (r = −0.34, p < 0.001), whereas a moderate correlation was found between LVBQ and DEXA scores (r = −0.34, p < 0.001). Conclusions: The LVBQ score demonstrates moderate correlation with DEXA and may serve as a reliable tool for preoperative BMD assessment. However, the CVBQ score showed weak correlation with both DEXA and HU, limiting its clinical utility in its current form. Further refinement of the CVBQ methodology is needed to enhance its accuracy and relevance for surgical risk assessment and postoperative outcome prediction. Full article

In many gold–antimony deposits throughout the world, the sequence of Au and Sb precipitation varies significantly. In high-temperature systems such as hydrothermal Au deposits, gold typically precipitates prior to antimony, whereas in lower-temperature systems (e.g., Carlin-type deposits), no consistent depositional sequence is observed. The Gutaishan Au-Sb deposit, located in the Xiangzhong Basin of the Jiangnan Orogenic Belt, South China, exhibits a distinct spatial segregation within a continuously evolving system of gold and antimony mineralization—a pattern commonly observed in many Au-Sb deposits throughout the region. To elucidate the mechanisms controlling Au-Sb co-occurrence and segregation, we conducted electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) major and trace element analyses of stibnite and pyrite from quartz veins across different ore zones within the Gutaishan deposit. Trace element signatures—such as Cu-Pb correlations and Hg/(Cu + Pb) ratios which classify stibnite into Woxi-type and Xikuangshan-type, and Co/Ni ratios classifies pyrite into magmatic–hydrothermal and sedimentary types—suggest that the ore-forming fluids were predominantly magmatic–hydrothermal in origin, with minor contributions from metamorphic basement fluids. The occurrence of low-temperature trace element signatures in the Au-Sb deposit indicates that temperature is the primary control on Au-Sb segregation. The thermodynamic model further confirms that high-temperature fluids favored the precipitation of Au veins, while lower-temperature fluids facilitated the co-precipitation of stibnite and gold in Sb-Au veins. Therefore, we propose a metallogenic model for the Gutaishan deposit that highlights temperature-driven Au-Sb segregation, resulting from the progressive cooling of the ore-forming fluids. Full article