GOLD-BEARING PROPERTY OF ORE ROCKS AND OCCURRENCE OF GOLD FROM SHILONGTOU GOLD DEPOSIT IN KAIHUA,WEST OF ZHEJIANG PROVINCE

Shilongtou gold deposit of Kaihua in west of Zhejiang belongs to fine grained disseminated ore type.Gold mineralization occurred in tectonic fragmented alteration zone of the Neoproterozoic strata.The mineral compositions of ore rocks and major gold-bearing minerals were investigated by using petrographic observations,electron probe and scanning electron microscopy.It shows that the major gold-bearing minerals are pyrite and arsenopyrite,with minor vein quartz,whereas,gold has not been detected in quartz,dolomite and clay minerals.Anaysis reveals that average gold content of pyrite and arsenopyrite are 181×10-6 and 207×10-6,respectively.Visible micrometer-size gold is dominant,with minor invisible nanometer-size gold.The former occurs in pyrite crystals or crystal edge in the form of inclusion gold grains,and the latter displays as nano particles of native gold in the pyrite and solid solution in arsenopyrite.