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The Makeng iron deposit in southwest Fujian is a significant iron polymetallic deposit containing various types of iron ore, including garnet magnetite, diopside magnetite, and quartz magnetite. The metallogenetic type of the deposit has been a subject of debate, particularly in relation to the genesis of magnetite and the source of iron. In situ microanalysis of trace elements in magnetite from different ores shows relatively low levels of V, Ti, Cu, and Zn, with higher concentrations of Ca and Si, indicating the characteristics of a skarn type deposit. The δ⁵⁷Fe values of the magnetite range from −0.091‰ to 0.317‰. Combining these data, whole-rock iron isotope analyses, including Juzhou and Dayang granites, diabase, and the Lower Carboniferous Lindi Formation sandstone, suggest that Fe in the magnetite primarily originates from granitic pluton, with potential contributions from diabase and the Lower Carboniferous Lindi Formation sandstone. Combined with field work, these results indicate that Makeng iron deposit is a skarn-type magnetite deposit associated with Yanshanian granitic intrusions. Therefore, the initial ore-forming fluid is postulated to be a high-temperature magmatic hydrothermal fluid with high oxygen fugacity. This fluid infiltrates spaces such as interlayer fracture zones between the Upper Carboniferous Jingshe Formation–Middle Permian Qixia Formation carbonate rocks and the Lower Carboniferous Lindi Formation sandstone, resulting in diverse magnetite ores due to metasomatism. The mineralization process of the Makeng iron deposit is basically the same, as it is composed of typical skarn deposits. Magnetite was mainly formed during calcic skarn formation stage, and this process persisted until the initial phase of the retrograde alteration of skarns. In contrast, sulfide minerals, including molybdenite, sphalerite, and galena, precipitated during the quartz–sulfide stage. Full article

JingFenCui is a type of rhodonite jade from the Changping district of Beijing, China, which is a manganese skarn deposit formed through the metasomatism of the granite aplite and Cambrian limestone. The pink color of JingFenCui is richer and brighter than that of rhodonite jade from other deposits. The surface of JingFenCui exhibits dendritic iron and manganese oxides, which is the outstanding advantage of rhodonite jade for carving works. The zoning pattern of mineralogy between the contact zone with the wallrock is obvious. The main skarn minerals consist mainly of spessartine, diopside, augite, manganotremolite, clino-suenoite, rhodonite, galena, etc. Compared with rhodonite jade from the Makeng in Fujian and the Luziyuan in western Yunnan, vittinkiite (MnSiO₃) is more concentrated in the rhodonite of the JingFenCui Deposit as a Mn-Ag-Pb-Zn-Fe polymetallic deposit. There is a good agreement among the rhodonite, amphibole, and galena in the spider diagrams of the trace elements. The results of trace elements and REE analysis show that the metallogenic fluids of the JingFenCui deposit are mainly from magma related to the Heixiongshan granite. It is suggested that the JingFenCui deposit is a manganese skarn deposit formed through the metasomatism of the manganese-bearing limestone and fine-grained granite of the Heixiongshan. Full article