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The process and mechanism of gold mineralization are frontier issues. The Dunbasitao deposit is the most important gold deposit discovered along the Armantai suture zone, East Junggar, NW China, which indicates the potential for future ore exploration in this area. Orebodies are mainly hosted in Lower Carboniferous Jiangbasitao Formation volcano-sedimentary rocks, and the ores are characterized by multistage pyrites. Based on microscopy and backscattered electron imaging studies, pyrites are classified into five types: the pre-ore framboidal/colloidal Py0; the early-stage coarse-grained, cubic, and homogeneous Py1; and the middle-stage fine-grained, cubic/pyritohedron Py2 that includes Py2a (core), Py2b (mantle), and Py2c (rim). The results of the EPMA and in situ LA-ICP-MS analyses show that trace elements of pyrite mainly occur in two forms: solid solutions and invisible or visible inclusions. Mn, Co, Ni, and As enter the pyrite lattice, whereas Ti occurs as mineral inclusions, and Au, Cu, Zn, Sb, and Pb can occur in both forms. Au and As show a positive linear relationship with r = 0.850. Py2b has much higher Au contents (20.1 to 201 ppm) than other pyrite types (Py0: 0.01 to 0.36 ppm; Py1: 0.01 to 0.02 ppm; Py2a: 0.31 to 2.48 ppm; and Py2c: 0.18 to 18.0 ppm). The Dunbasitao deposit is classified as an orogenic gold deposit using the two latest machine learning classifiers based on pyrite trace element data. Fluid immiscibility, sudden cooling, and the substitution of S1− with As1− might be crucial mechanisms leading to Au precipitation. Initial ore-forming fluids brought major amounts of As, Au, Co, Ni, Se, Zn, Ag, Cd, Sn, and other elements, and the Jiangbasitao Formation host rocks contributed a certain amount of As, Ni, Cu, Sb, Pb, and Bi, at least. [ABSTRACT FROM AUTHOR]

The Xikuangshan antimony (Sb) deposit is the world's largest known Sb deposit. Due to the lack of suitable minerals for reliable high-precision radiometric dating, it remains difficult to determine the exact age of Sb mineralization in this deposit. Here, we report the first LA-MC-ICP-MS U-Pb ages of syn-stibnite calcite from this deposit. The dating results indicate the presence of at least two stages of Sb mineralization in the Xikuangshan ore district. The calcite-stibnite veins in the Daocaowan ore block probably formed during the Paleocene (58.1 ± 0.9 Ma), representing an early stage of Sb mineralization, while the quartz-stibnite vein in the Feishuiyan ore block probably formed during the Eocene (50.4 ± 4.4 Ma, 50.4 ± 5.0 Ma, and 51.9 ± 1.6 Ma), representing a late stage of Sb mineralization. The new calcite U-Pb ages are significantly younger than the calcite Sm-Nd ages (124.1 ± 3.7 Ma, 155.5 ± 1.1 Ma) reported by previous researchers. We suggest that Sb mineralization of the South China antimony metallogenic belt may be related to tectono-thermal events during Paleogene, possibly linked to high heat flow during the subduction (ca. 60–40 Ma) of the Pacific Plate beneath the Eurasian Plate and/or the Indo–Asian Collision (began at ca. 61 Ma). The young in situ U-Pb ages of calcite challenge the idea of late Mesozoic Sb mineralization in the South China antimony metallogenic belt, suggesting the requirement for more high-precision dating studies. [ABSTRACT FROM AUTHOR]

Antimony (Sb) is a trace element applied widely in modern industry. A large number of tailing solid wastes are left and accumulated in the mining area after purifying the precious antimony from the antimony ores, causing serious pollution to the environment. The major aim of this study is to investigate the feasibility of utilizing antimony tailing coarse aggregate (ATCA) as a complete substitute for natural coarse aggregate (NCA) in high-strength concrete. Concrete specimens with 25%, 50%, 75%, and 100% ATCA replacing the NCA in conventional concrete were prepared for evaluating the performance of ATCA concrete. The investigators find that ATCA concrete has good workability, and the mechanical properties and long-term behavior (shrinkage and creep) of ATCA concrete with all replacement levels are superior to those of NCA concrete. The durability indices of ATCA concrete, such as the frost-resistant, chloride permeability, and resistance to carbonation, are better than those of NCA concrete. While the alkali activity and cracking sensitivity behavior of ATCA concrete seem to be decreased, nevertheless, the difference is not significant and can be neglected. The researchers demonstrate that all of the control indices of ATCA concrete meet the requirements of the current industry standards of China. Overall, ATCA can be used in concrete to minimize environmental problems and natural resources depletion. [ABSTRACT FROM AUTHOR]

In this research, the sustainable applications for utilizing antimony tailing coarse aggregate (ATCA) in concrete is investigated. Comprehensive verifications were performed by a series of experiments on the characteristic of ATCA and the toxicity risks of concrete. Firstly, a real case study of utilization of ATCA as a complete substitute for natural coarse aggregate (NCA) in high strength concrete was conducted. Then, chemical composition of ATCA was tested. It is demonstrated that the essential mineral is SiO2 and the lithology of ATCA is quartzite. The mechanical properties, coarse quality of ATCA, and NCA were studied and compared. The compressive strength, splitting tensile strength, and compressive elastic modulus of ATWR are 221.51 MPa, 5.93 MPa, and 3.33 × 104 MPa, which are 1.31, 2.22, 1.40 times of that of NR, respectively. All of the quality control indices of ATCA meet the requirements of the current industry standards of China. Finally, the toxicity risks of ATCA concrete were investigated. It is illustrated that the leaching of main heavy metals including Sb, As, Hg, Pb, Cd, and Zn in the ATCA concrete under different pH conditions are below the regulatory limits. The utilization of antimony tailing has significant environmental and economic benefits. [ABSTRACT FROM AUTHOR]