山西繁峙义兴寨金矿床金矿物特征研究

Characteristics of gold-bearing minerals in the Yixingzhai gold deposit,Fanshi County,Shanxi Province

义兴寨金矿属于典型的石英脉型金矿床。金矿物以单颗粒的银金矿为主,有少量的自然金。粒度多集中在10～50μm;形态多为浑圆粒状、麦粒状、不规则粒状、角砾状、细脉状等。主要以包体金、粒间金、裂隙金存在于黄铁矿、黄铜矿、石英等颗粒中。利用数量和面积两种统计方法分别对金矿物进行形态、粒度、存在状态的特征统计,显示不同类型金矿物在出现率和面积配分特征上有较大差别。化学成分中普遍含有Fe、S、Cu、Zn、Pb元素,分析得出Fe、S与Au呈不同程度的反相关关系,Pb元素含量相对稳定,Cu、Zn元素变化较大;结合Au、Ag含量与温度关系,显示金矿物形成于中低温环境。成色为510.7~887.9,平均653.6,显示浅成成矿环境。纵向上,从1350 m标高到1070 m标高,金矿物的成色平均值由778.4逐渐降低为651.7,显示逆向分带特征,指示深部1070 m标高以下仍有稳定矿体存在。

The Yixingzhai gold deposit is located in Fansi County,Shanxi Province,whose mineralization belongs to quartz-vein type.The main gold mineral is single electrum,together with minor native gold.The gold minerals commonly assume rounded,wheat-like,irregular brecciated and veinlet forms,with grain size in the range of 10～50 μm in diameter.They occur mainly in gold-bearing minerals such as pyrite,chalcopyrite and quartz,in the form of inclusion gold,intercrystalline gold and fissure gold.The authors made statistical analysis of the shapes,grain sizes and modes of occurrence of gold minerals by using quantity statistical method and area statistical method,and the results indicate that different gold minerals show remarkable differences in occurrence rate and area distribution.Gold-bearing minerals generally contain iron,sulfur,copper,zinc and lead.Analytical results indicate that iron and sulfur show inverse correlation with gold,and have stable lead content and remarkably varying copper and zinc content.In combination with the relationship between the temperature and the Au and Ag content,the authors suggest that the gold minerals formed in medium-low temperature.The average gold fineness ranges from 510.7 to 887.9 with an average of 653.6,suggesting an epithermal metallogenic environment for the Yixingzhai gold deposit.From 1350 m level to 1070 m level,the average fineness of gold minerals gradually decreases from 778.4 to 651.7,showing characteristics of reverse zoning and indicating that there probably exist stable ore bodies below 1070 m level.