安吉矿区是以热液型铅锌铜为主的多金属矿床,工程样化验结果显示,各类矿石均含有高品位的银,可以独立划分银矿体.岩矿显微鉴定、SEM/EDS及EPMA分析结果表明,矿区中的Pb、Zn和Cu主要以方铅矿、闪锌矿、黄铜矿形式存在,银与这些硫化物有密切的依存关系.对数十个典型矿石光薄片进行了研究,发现矿区多数铅锌铜矿石中金、银主要以类质同像形式存在于方铅矿、闪锌矿、黄铜矿、黄铁矿等硫化物中,金、银含量分别达0.03％ ～0.57％和0.02％～3％.而热液脉型铅锌矿石中的银主要以两种独立银矿物(硫锑铜银矿和银锑黝铜矿)的形式,在方铅矿之中呈粒状、短柱状、叶片状、树枝状、不规则状发育,单颗粒粒度多在10～60μn之间,少数可达100 μm,集合体粒度可达200μm.另外这两种独立银矿物之中还存在类质同像形式的金,据统计,金、银含量分别达0.14％～0.35％和10.98％～69.12％.因此,方铅矿为银独立矿物的主要载体之一,且富方铅矿的矿石中更容易发现独立银矿物.%There exists a lead-zinc-copper polymetallic deposit of hydrothermal type in the Anji mining area. The ore samples from prospecting trenches and bore holes were analyzed and tested, and the results indicate that all kinds of ores contain high grade of silver, and hence the silver ore body can be distinguished from other ore bodies. Based on microscopic examination, SEM/EDS and EPMA analysis, the authors found that Cu, Pb and Zn occur respectively in chalcopyrite, galena and sphalerite, and silver may be closely coexistent with Pb-Zn-Cu sul-fides. Based on studying tens of typical thin sections by using microscopic examination, SEM/EDS and EPMA, the authors also found that in most lead-zinc and copper ores, gold and silver exist as isomorphism in galena, chalcopyrite, sphalerite and pyrite, with the content of 0.03% ～0.57% and 0.02% ～3% respectively. In the hydrothermal filling type lead-zinc ores, silver exists mainly in the form of independent silver-bearing minerals, such as Ag-tetrahedrite and polybasite, which carry small amounts of isomorphic gold and occur mainly in galena as micro-inclusions in the subhedral crystal, short prismatic, blade, lath-shaped, dendritic and irregular forms. Actually, single particle sizes of Ag-tetrahedrite and polybasite are generally in the range of 10～60 μm, with only a few grains reaching 100 μm. In addition, the silver mineral aggregates canl be up to 200 μm in size. The silver and gold in the independent silver-bearing minerals can reach 10.98% ～69.12% and 0.14% ～0.35% respectively. The results obtained show that galena is a very important silver-carrying mineral, and the ores with rich galena are especially likely to contain independent silver-bearing minerals.
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