云南都龙锡锌多金属矿床自然铋和自然银矿物学特征研究

摘要

The Dulong Sn-Zn polymetallic deposit is one of China's three large cassiterite sulfide deposits, which occurs in the outer contact zones of the later Yanshan Laojunshan Granites.Ore minerals such as ferro-sphalerite,cassiterite,pyrrhotite,pyrite and chalcopyrite,were formed in intermediate and high tempera-tures.Native bismuth and native silver,two kinds of native element minerals,have been discovered recently in this deposit.Their mineralogical features have been studied with an optical microscope,BSE,X-Ray scan, EDS and Laser-Raman spectrum.Both of native bismuth and native silver,most as irregularly shape fine grains occurred in inner and fine pores of sulfide minerals,have high purity with greater than 90%,which co-exist with chalcopyrite and galena,etc.Based on these studies mentioned above,it was suggested that there might be multi-stages during the magmatic hydrothermal mineralization,and native bismuth and native silver might formed in the last stage with low-middle temperatures and poor sulfur condition.This study also sugges-ted that there might find the Ag-Bi mineralization on the outside of the skarn Zn-Sn mineralization.%都龙锡锌多金属超大型矿床是我国三大锡石硫化物矿床之一，该矿床产出于燕山晚期老君山花岗岩外接触带，矿石矿物以铁闪锌矿、锡石、磁黄铁矿、黄铁矿、黄铜矿等中高温矿物为主。自然铋和自然银为该矿床新发现的2种自然元素矿物，利用光学显微镜，通过电子探针背散射分析、面扫描分析和能谱分析，借助激光拉曼光谱，对它们的矿物学特征了进行了研究。研究表明，自然铋和自然银纯度较高，原子百分比均大于90％，多呈不规则状微细粒，与黄铜矿、方铅矿等共生，赋存于硫化物矿物内部或之间的微细孔隙，形成晚于黄铜矿和方铅矿。在此基础上，认为该矿床存在多阶段矿化，自然铋和自然银形成于岩浆热液晚期阶段的中低温、贫硫环境，并指示夕卡岩型锌锡矿化外围具有找寻银铋矿的潜力。