豫西董家埝银矿床银的赋存状态研究

Research on modes of occurrence of silver in Dongjianian silver deposit,western Henan Province

董家埝银矿床位于豫西小秦岭地区小河岩体的南缘,矿体赋存于中元古代小河岩体与太古界太华群、中元古界官道口群、早古生界寒武系及新生界第四系地层的接触部位。文章通过矿相学研究、电子探针定量分析、能谱半定量分析及电子探针面扫描分析等手段对该矿床矿石中银的赋存状态展开研究。结果表明,董家埝银矿床银矿物主要为自然银、辉银矿、硫锑铜银矿、金银矿、银金矿,载银矿物主要为黝铜矿、方铅矿、闪锌矿、黄铜矿,其中黝铜矿是银的主要载体矿物。银主要以可见银及不可见银赋存,可见银包括独立银矿物、显微包体银;不可见银包括晶格银、次显微包体银。赋存形式以独立银矿物、显微包体银及晶格银为主。

The Dongjianian silver deposit is located on the southern margin of Xiaohe rock mass in Xiaoqinling area,western Henan Province.The orebodies occur in the contact zone between Mesoproterozoic Xiaohe rock mass and early Palaeozoic Cambrian,Mesoproterozoic Guandaokou Group,Archaeozoic Taihua Group and Cenozoic Quaternary strata.Based on the electron microprobe analysis(quantitative analysis and element mapping),energy spectrum semi-quantitative analysis and ore microscopic study,the authors detected that the silver minerals of the Dongjianian silver deposit include native silver,argentite,polybasite,kustelite and electrum,while silver carrier minerals are tetrahedrite,galena,sphalerite and chalcopyrite,with tetrahedrite being dominant.Silver occurs in two types,namely visible silver and invisible silver.Visible silver exists as independent silver minerals or microinclusions in other minerals.Invisible silver exists in sulfides as lattice silver or sub-microinclusions.However,independent silver minerals,microinclusions and lattice silver are the main modes of occurrence of silver.