Occurrence Modes of Tungsten,Tin,Bismuth,Silver and Molybdenum from the Vein Type Tungsten Polymetallic Deposits in Northern Guangdong,China

Detailed mineragraphy and electron probe analysis were carried out on the samples from Hongling,Shirenzhang,Meiziwo and Jubankeng vein type tungsten deposits in northern Guangdong,China.We found several grains of mangancolumbite and wolframoixiolite and observed a wide range of intergrowth phenomenon of wolframite and scheelite in the Hongling deposit.A large amount of stannite found in Shirenzhang,Meiziwo and Jubankeng tungsten deposits are distributed along the edges of chalcopyrite and sphalerite or occurs as disseminated drops in chalcopyrite.Some stannites even include cassiterite.Silver mineralization to some extent occurs in the Hongling,shirenzhang and Meiziwo tungsten deposits.Based on the EDX analysis of Ag-bearing minerals,Ag-bearing heyrovskyite,schirmerite(No.1,2,3 subspecies),matildite,proustite,stephanite,an stromeyerite have been identified with minor unnamed Pb-Bi-S minerals(4.78%~13.25% Ag),Ag-Cu-S minerals(2.9%~12.19% Ag),As-S-Ag minerals(71.01%~90.74% Ag),and Cl-Pb-Cu-S mineral(9.3% Ag).Silver-bearing minerals in the Hongling deposit are mainly scattered as irregular grains in sphalerite and silicate minerals,and formed simultaneously as the main sulfides did.Ag-bearing minerals in the Shirenzhang deposit mainly contain Ag-bearing Cu-S minerals and Ag-Cu-S minerals,which form Ag-bearing mineral sphalerite belt at the edge of chalcopyrite,while Ag-bearing Pb-Bi-S and Bi-Ag-S minerals distribute locally.Meiziwo deposit contains less Ag-bearing Pb-Bi-S,Bi-S and As-Pb-Ag minerals but independent silver minerals and small amount of natural silver occurring in galena and filling the fractures of sulfides.There are various Ag-bearing minerals with high contents in the Shirenzhang,Meiziwo tungsten deposits indicating good prospect of development.Metasomatic Ag-bearing minerals developed and filling along fractures of the samples from two deposits indicate a strong silver mineralization imposed by late-stage hydrothermal fluid.Bismuth minerals in the four deposits are mainly bismuthinite and bismuth and part of the deposits are dominated by Ag-Pb-Bi sulfosalt.Several grains of tsumoite were found in the Hongling deposit and are paragenetic with with bismuthinite;unnamed Cu-Bi-S minerals were found in the Shirenzhang deposit.Compositions of the sphalerites from the four deposits are different,Hongling and Jubankeng deposits containing no Cd and the Shirenzhang and Meiziwo deposits containing higher Cd content.But iron content in the Hongling tungsten deposit varies greatly.