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Abstract:Although numerous W-Sn-Pb-Zn polymetallic deposits are located in southern Hunan, and In-bearing deposits are related to W-Sn-Pb-Zn polymetallic deposits, Indium mineralization in southern Hunan is poorly studied. In order to investigate the In mineralization of the Xianghualing orefield, which is a typical orefield in southern Hunan, ore bulk chemistry, microscopic observation, and electron-probe microanalysis of vein-type (type-I) and porphyry-type (type-II) Sn-Pb-Zn orebodies were studied. The In contents of the type-I orebodies varies from 0.79 to 1680 ppm (avg. 217 ppm, n = 29), and that of the type-II orebodies varies from 10 to 150 ppm (avg. 64 ppm, n = 10). Although chalcopyrite and stannite contain trace amounts of In, sphalerite is the most important In-rich mineral in the orefield. Sphalerite in type-I orebodies contains from <0.02 to 21.96 wt % In, and in type-II orebodies contains from <0.02 to 0.39 wt % In. Indium-rich chemical-zoned sphalerite contains 7 to 8 wt % In in its core and up to 21.96 wt % In in its rim. This sphalerite may be the highest In-bearing variety in Southern China. The Cd contents of the In-rich sphalerite ranges from 0.35 to 0.45 wt %, which places it in the the "Indium window" of the Cu-In-S phases. The geological and structural features of the Xianghualing orefield indicate that the In mineralization of the two types of In-bearing Sn-Pb-Zn orebodies is related to the volatile-rich, In-rich, A-type granites, and is controlled by the normal faults of magmatic-diapiric activity extensional features.

The preparation of X-zeolite powder was investigated in hydrothermal system, the crystal growth process of X-zeolite in hydrothermal condition was characterized by means of X-ray diffraction, scanning electron microscope and infrared ray. The results show that X-zeolite powder with uniform granularity and intact crystal shape can be obtained in hydrothermal system of acid-treated stellerite-NaOH-NaAl(OH)4-H20; the crystallite size is in the range of 2 -3 t~m. The best reaction time of hydrothermal preparation is 6 h. The formation phases of X-zeolite crystal are as follows: dissolution of feedstocks ---formation of [SiO4] 4-and [A104 is-tetrahedron, many-membered ring,/3 cage --~ formation of crystal nucleus and nano-partiele --~ aggregation growth of nano-particle --~ coalescence growth of crystallite. The crystal habits of X-zeolite are intimately related with crystallization orientation of/3 cage in crystal and with its coupling stability on every crystal face family.

Zn-Cd-S series minerals not only comprise industrial resources for Zn and Cd, but are also significant mineralogical indicators for hydrothermal ore-forming processes. Due to its unique formation conditions and rare occurrence, our understanding of the formation of zincian greenockite in natural systems is limited. Zincian greenockite was discovered during mineralogical studies in the Saishitang Cu skarn deposit, Qinghai Province, Northwest China. This provided an ideal opportunity to assess the occurrence and formation of zincian greenockite in skarn-type deposits. Ore minerals were observed using reflected-light microscopy, and the zincian greenockite was further analyzed using electron-probe microanalysis (EPMA) and X-ray diffraction (XRD). The zincian greenockite occurs in the bornite-chalcopyrite ores and is composed of subhedral to anhedral grains approximately 50 × 150 µm 2 to 200 × 300 µm 2 in size, replaces the bornite, and is replaced by native silver. Two phases (I and II) were identified based on back-scattered electron images, X-ray element-distributions maps, and EPMA data. The textural relationship indicated that Phase I was replaced by Phase II. Phase I contained high Zn (14.6 to 21.7 mol % ZnS) and low Cd (72.4 to 82.2 mol % CdS), while Phase II contained low Zn (5.6 to 9.1 mol % ZnS) and high Cd (85.4 to 89.9 mol % CdS). The zincian greenockite was formed at temperature of 300~270 • C during the transformation from a reducing environment to an oxidizing one in the late stage of the mineralization process in the Saishitang deposit.

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