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Due to the inhomogeneity and anisotropy of mine rock bodies, ionic rare earth ore bodies exhibit varying pore structures at different depths. This research focuses on an ionic rare earth mine in Fujian Province, where in situ ore samples rather than remodeled soil samples were studied. Samples from the fully weathered layer at depths of 1 m, 12 m, and 21 m, both before and after leaching, were collected for onsite analysis. Microscopic pore characteristics were evaluated using scanning electron microscopy, and digital image processing was utilized to study the evolution of the pore scale, distribution, and shape in rare earth ore samples at various depths pre- and post-leaching. The results indicate an increase in the ore body's porosity with the depth of the ore samples both before and after leaching. The variation in pore scale is predominantly dictated by the ratio of macropore and large pores. Pre-leaching, the middle ore sample showcased the highest uniformity, with the upper part being the most irregular. Post-leaching, the highest uniformity was observed in the lower ore samples, with the upper part remaining irregular. Pre-leaching, as depth increased, the pore distribution in ore samples became more dispersed, with decreasing orderliness. Post-leaching, the orderliness was most improved in upper ore samples, while middle ore samples became the least orderly. Additionally, before leaching, pore-shape roughness increased with depth; after leaching, the pore shape became more rounded as depth increased, simplifying the pore-shape structure of the ore samples both before and after leaching. [ABSTRACT FROM AUTHOR]

Abstract: The Jian kiln, located in present-day Jianyang county of Fujian province, mainly produced black-glazed tea bowls. Jian tea bowl was used as a utensil for tea tasting and was greatly appreciated by emperor Huizong of the Northern Song dynasty. The black glaze of Jian bowl was sometimes marked with streaks or spots, usually called “hare''s fur” or “oil spot”, which are the crystalline markings of iron oxide precipitated during firing in the dragon kiln. In this study, black-glazed Jian bowl sherds excavated from the late Northern Song strata of Luhuaping and Daluhoumen Jian kiln sites were adopted as test samples. Based on the physico-chemical foundation for the formation of glaze microstructure, the correlation among composition, microstructure, and visual appearance has been investigated by means of energy-dispersive X-ray fluorescence, X-ray diffraction, and field emission electron microscopy. For the first time, the study provides realizing proofs for two kinds of microstructural forming mechanics. [Copyright &y& Elsevier]

The persimmon-red glazed wares, characterized by a reddish-brown appearance with high gloss, were one of the main varieties of glazes manufactured in Jian kilns (Fujian province, China) during the Song Dynasty. Densely packed dendritic ε-Fe 2 O 3 crystals in microns size composed of several branches were observed in the glazes surfaces of Jian persimmon-red wares. The branches, consisting of well-arranged rod-like crystals with offset around 110 or 220 nm, could serve as sub-micron mirrors to improve the glaze gloss. A number of Al and few Ti and Mn ions were detected to substitute Fe ions in ε-Fe 2 O 3 crystals. The Al substitution could play a dual role in ε-Fe 2 O 3 structure: (1) stabilizes the structure through increasing of cationic disorder and (2) makes the appearance less dark, which could account for the nice persimmon-red appearance of Jian wares. Besides, zircon, quartz, hematite, jacobsite and mullite were also observed in the glaze surfaces. • Dendritic ε-Fe 2 O 3 crystals in microns size composed of several branches were observed in the glazes surfaces of Jian persimmon-red wares. • The branches consisting of well-arranged rod-like crystals with offset ~110 or 220 nm could serve as sub-micron mirrors to improve glaze gloss. • Al substitutions in ε-Fe 2 O 3 crystals could play a dual role of acting as stabilizers to increase cationic disorder and making appearance less dark. • A few impurity crystals including zircon, quartz, hematite, jacobsite and mullite were detected in the glazes surfaces. [ABSTRACT FROM AUTHOR]