Abstract
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 μm2 to 200 × 300 μm2 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.
Highlights
The Zn-Cd-S component system is of theoretical and practical significance for mineralogy and materials science [1,2,3]
Zincian greenockite was harder than bornite (Figure 6a) and the grains were subhedral to anhedral (Figure 6), approximately 50 × 150 μm2 to 200 × 300 μm2, and occurred on the edges of the chalcopyrite, quartz, and calcite
The bornite was replaced by the zincian greenockite later than the actinolite, which was replaced by the native silver (Figure 6)
Summary
The Zn-Cd-S component system is of theoretical and practical significance for mineralogy and materials science [1,2,3]. Zincian greenockite was previously discovered during during critical critical metals metals studies [26]. This provides a good opportunity to assess how the zincian greenockite was studies [26]. This provides a good opportunity to assess how the zincian greenockite was formed formed the during the mineralization processes of skarnIn deposits. This paper, investigations mineralogical during mineralization processes of skarn deposits. Cu deposit were first performed, after which the mineral for ores of the Saishitang Cu deposit were first performed, after which the mineral chemistry and chemistry and unit-cell parameters of the zinc greenockite were obtained. The forming unit-cell parameters of the zinc greenockite were obtained.
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