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Using different iron sources of industrial iron oxide, loess, slag, and golden soil, iron elements were introduced into the formula respectively, and celadon samples were prepared in a reducing atmosphere. To reveal the influence of iron source on glaze color, the celadon samples were analyzed by Spectrophotometer, X-ray fluorescence spectroscopy, X-ray diffractometer, scanning electron microscope, and X-ray photoelectron spectrometer. The results show that the glaze color of the samples is quite different, samples using iron oxide and golden soil as iron source raw materials are sky-green, the loess sample is olive green, and the slag sample is similar to the bean green. There are many quartz crystals in the glaze of iron oxide samples, and the turbidity is high. The liquid-liquid phase separation size close to the quartz crystal is large, and far away from the crystal is small. Industrial iron oxide is the easiest to reduce, followed by goethite in golden soil, and reduction of hematite in slag and the iron in loess in the form of isomorphic is successively more difficult. The difference in the form of occurrence of iron is the most essential factor that causes the difference in glaze color. [ABSTRACT FROM AUTHOR]

Jun ware is stoneware created in the late Northern Song dynasty (12th century) with a blue glaze combining transparent-blue and whitish-opaque submillimetric areas. The glaze has a glass nanostructure with lime-rich droplets in a silica-rich matrix resulting from a high temperature liquid-liquid phase separation. Calcium-rich opaque and calcium-poor transparent areas are combined. Iron is more oxidised in the calcium rich areas (≈17–20% Fe2+) than in the calcium poor areas (≈60–70% Fe2+) of the glaze. Therefore, iron is oxidised in the lime-rich droplets and reduced in the silica-rich matrix. The sky- like appearance of the glaze is due to the combination of the light absorption in the transparent-dark-blue Fe2+ rich areas and scattering in the white-yellowish Fe3+ rich areas. Copper appears mainly oxidised but in the red areas a few small copper nanoparticles are present and iron appears more oxidised. The result indicates the simultaneous reduction of copper and oxidation of iron. • Lime-rich and silica-rich glass nanostructure. • Iron is mainly oxidised in the lime-rich droplets and reduced in the silica matrix. • Copper is mainly present as Cu+. • Simultaneous reduction of copper and oxidation of iron in the red areas. [ABSTRACT FROM AUTHOR]

The oxidation state of iron in minerals is an important part of analysis. Especially for minerals used as a raw material for metallurgical processes, the oxidation state has a significant impact on the process. One crucial impact is the varying carbon requirement in smelting furnaces, which can be significantly different if the oxidation state is not assessed correctly. Compared to methods usually used to determine the oxidation state, a relatively simple and fast thermogravimetric method is proposed in this article. As a sample, a detailed analyzed chromite sample from Turkey is used. Bulk chemical analysis, Raman spectroscopy, X-ray diffraction, and QEMSCAN® are used to determine the preconditions of the sample. Mössbauer spectroscopy is used as a reference method to determine the oxidation state of iron in the sample. Uncertified wet chemical methods are investigated as well in this paper and the results are compared with the reference measurement. Using a thermochemical simulation tool, parameters for the thermogravimetric method are investigated and the limitation of this method is examined. The mean ferrous ratio in the sample determined by the proposed method is 75.205%, which is only slightly lower than the ferrous ratio of 76% determined by Mössbauer spectroscopy. [ABSTRACT FROM AUTHOR]