Phase relations in the Cu 2 S-PbS-Sb 2 S 3 system; an experimental appraisal and application to natural polymetallic sulfide ores
Phase relations in the Cu 2 S-PbS-Sb 2 S 3 system; an experimental appraisal and application to natural polymetallic sulfide ores
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Cu 2 S-PbS-Sb 2 S 3 体系中的相关系；
DOI：
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
H. Bernhardt
中科院分区：
文献类型：
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作者：
K. Pruseth;B. Mishra;H. Bernhardt
通过真空二氧化硅管（+或-卤化物通量）技术在500度、440度和300摄氏度下对Cu 2 S-PbS-Sb 2 S3系统进行了实验研究。此外，环境硫逸度的平衡相组合已被监测的两个磁黄铁矿指示剂方法。与Hoda和Chang（1975）的早期结果相反，在500 ℃时，在黑锰矿和Z相中的固溶度明显变小，而富Cu 2S和Sb 2S 3的熔体区域更广。富Cu 2S熔体场的位置也发生了明显的变化。从富PbS端到富Sb 2S 3端，黑锰矿场逐渐变小，贫Cu 2S边界随着Sb 2S 3的增加而远离PbS-Sb 2S 3二元体。早先声称tintinaite是Z相的天然类似物得到证实。在500 ℃和440 ℃时，Falkmanite呈现出明显的相态。不含Cu的meneghinite可能在>或= 550 ℃的温度下稳定。在300摄氏度时不存在黑锰矿和Z相，这与Hoda和Chang（1975）的早期研究有很大的不同。此外，铌钠闪石消失，半透明辉石出现，导致建立了水硼镁石，水硼镁石半透明辉石，和辉锑矿半透明辉石连接线。在500度和440摄氏度内的三相领域和两相边界上的f（sub s 2）的变化是一致的。在440 ℃条件下进行的f（sub s2）实验表明，硫锑铅矿是通过硫化反应形成的：3硫锑铅矿+1/2S2 =硫锑铅矿+辉锑矿，并成功地解释了多种多金属矿床中有关天然硫盐组合的矿物学和组成。值得注意的是，天然meneghinite的组合物绘图在富PbS边界的meneghinite字段上的Cu 2 S-贫侧。天然的Sb 2S 3丰富的meneghinites的虚拟缺席可以解释为更多的铜的稳定性的要求，这是不现实的地质在一个模型的热液流体。此外，相对较低的f（子S2）值的稳定性的meneghinites可能是另一种可能性。稀有的相，如辉铜矿和Skinnerite可以解释为极低的硫逸度值，超出巴顿f（子S2）-T制度，这是必不可少的稳定性。
The system Cu 2 S-PbS-Sb 2 S 3 has been experimentally studied at 500 degrees , 440 degrees , and 300 degrees C by the evacuated silica tube (+ or - halide flux) technique. Additionally, the ambient sulfur fugacity of equilibrium phase assemblages has been monitored by the two-pyrrhotite indicator method. Contrary to the earlier results of Hoda and Chang (1975), the extents of solid solubility in meneghinite and phase Z are distinctly smaller and the Cu 2 S- and Sb 2 S 3 -rich melt fields at 500 degrees C are more extensive. There is also a marked shift in the position of the Cu 2 S-rich melt field. The meneghinite field gradually tapers down away from its PbS-rich end to the Sb 2 S 3 -rich end and the Cu 2 S-poor boundary moves away from the PbS-Sb 2 S 3 binary with increasing Sb 2 S 3 . The earlier claim that tintinaite is the natural analogue of phase Z is corroborated. Falkmanite appears as a distinct phase at 500 degrees and 440 degrees C. Cu-free meneghinite can possibly be stable at a temperature > or = 550 degrees C. The absence of meneghinite and phase Z at 300 degrees C is a major deviation from the earlier study of Hoda and Chang (1975). Further, robinsonite disappears and semseyite appears leading to the establishment of bournonite-boulangerite, bournonite-semseyite, and chalcostibite-semseyite tie lines. Variations in f (sub s 2 ) at 500 degrees and 440 degrees C within the three-phase fields and on the two-phase boundaries are consistent. The f (sub s 2 ) -imposed experiments in the chalcostibite-zinkenite-stibnite field at 440 degrees C reveal that famatinite forms according to the sulfidation reaction: 3 chalcostibite + 1/2S 2 = famatinite + stibnite.Mineralogy and composition of pertinent natural sulfosalt-bearing assemblages from a wide variety of polymetallic ore deposits are successfully explained in the light of the present experimental results. Significantly, the compositions of natural meneghinites plot at the PbS-rich boundary of the meneghinite field on the Cu 2 S-poor side. The virtual absence of natural Sb 2 S 3 -rich meneghinites can be explained by the requirement of more copper for their stability which is not geologically realistic in a model hydrothermal fluid. Additionally, relatively low f (sub S 2 ) values essential for the stability of meneghinites may be another possibility. Rarity of phases such as chalcostibite and skinnerite can be explained by the extremely low sulfur fugacity values, beyond the Bartonian f (sub S 2 ) -T regime, that are essential for their stability.