Diffusion in sulfide minerals and its application to ore deposits

DIFFUSION IN SULFIDE MINERALS AND其应用程序ONEDEPOSITSDiffusion coefficients fortransition元素in natural sphalerite were determined experimentally as a function oftemperature and as_2 using radioacive <54>Mn, ^<59>Fe, ^<60>Co，<63>Ni and ^<65>Zn. The tracer was deposited on a polished surface of natural sphalerite as a 1 1drop of aqueous chloride solution. The doped sphalerite was then heated in sealed silica tubestogether with an iron and/or synthesized pyrrhotite and/or pyrite aS2 buller，The tracer distribution was determined by measuring and emissions of powder sampled from successive4 - 8 m thick layers of the sphalerite chip. Results of diffusivity measurements are asfollows.1.Logarithms of diffusion rates for ^<59>Fe(d_ <Fe> cm^2s^<-1>) normal to the cleavage （110）under Fe-FeS as_2 buffer are -11.0 0.3 at 800 C and -11.7 0.2 at 700 C. Log(d_ <Co>) are -10.7 0.2and -11.5 .3，respecively. Log(d_zn_ < cm^2s^<-1>) normal to the cleavage (110) under Fe-FeS as_ <2> buffer are-10.9 0.2 at 800 C and -11.8 0.3 at 700 C. Log(D< _ni >) are -10.9 0.3 and -12.0 0.3，respectively.2. The dependence of <59>Fe diffusivity on as_2 is clearly observed in The 800 - C and700 C experiments. ^<59>Fe diffusion rates are lower at higher as_2 conditions (as_2 =10^<-2.9>，fe _< 1 - x ^ s - s _< liq >. buffer;d_ <Fe>=10^<-11.0 .3> at 800 C) and higher at lower as_ <2>(as_ <2> =10^<- 9.0>, Fe- fes buffer；D< _fe > = 10^<-11.3 0.2> at 800 C).3. Diffusion rates for ^<60>Co parallel to the (110) plane ofsphalerite at 800 C approximately twice that normal to (110). Sphalerites from metamorphosedBesshi-type deposits in Japan have different element abundances but are characterized by a distinctlack of compositional zoning.它是支持sphalerites were homogenized by diffusionprocesses during regional metamorphism. Calculated annealing times are 16 m.y. at 350 - C和240 m.y。at 300c, assuming 1 millimeter mean displacement of zinc atoms in sphalerite。

DIFFUSION IN SULFIDE MINERALS AND ITS APPLICATION TO ONEDEPOSITSDiffusion coefficients for transition elements in natural sphalerite were determined experimentally as a function of temperature and aS_2 using radioacive ^<54>Mn, ^<59>Fe, ^<60>Co, ^<63>Ni and ^<65>Zn. The tracer was deposited on a polished surface of natural sphalerite as a 1 1 drop of aqueous chloride solution. The doped sphalerite was then heated in sealed silica tubes together with an iron and/or synthesized pyrrhotite and/or pyrite aS2 buller, The tracer distribution was determined by measuring and emissions of powder sampled from successive 4 - 8 m thick layers of the sphalerite chip. Results of diffusivity measurements are as follows.1.Logarithms of diffusion rates for ^<59>Fe(D_<Fe> cm^2s^<-1>) normal to the cleavage (110) under Fe-FeS aS_2 buffer are -11.0 0.3 at 800゜C and -11.7 0.2 at 700゜C. Log(D_<Co>) are -10.7 0.2 and -11.5 0.3, respecively. Log(D_Zn_< cm^2s^<-1>) normal to the cleavage (110) under Fe-FeS aS_<2> buffer are -10.9 0.2 at 800゜C and -11.8 0.3 at 700゜C. Log(D<_Ni>) are -10.9 0.3 and -12.0 0.3, respectively.2. The dependence of ^<59>Fe diffusivity on aS_2 is clearly observed in the 800゜C and 700゜C experiments. ^<59>Fe diffusion rates are lower at higher aS_2 conditions (aS_2=10^<-2.9>, Fe_<1-x^S-S_<liq>. buffer; D_<Fe>=10^<-11.0 0.3> at 800゜C) and higher at lower aS_<2>(aS_<2> = 10^<-9.0>, Fe-FeS buffer; D<_Fe> = 10^<-11.3 0.2> at 800゜C).3. Diffusion rates for ^<60>Co parallel to the (110) plane of sphalerite at 800゜C approximately twice that normal to (110). Sphalerites from metamorphosed Besshi-type deposits in Japan have different element abundances but are characterized by a distinct lack of compositional zoning. It is suggested that sphalerites were homogenized by diffusion processes during regional metamorphism. Calculated annealing times are 16 m.y. at 350゜C and 240 m.y. at 300゜C, assuming 1 millimeter mean displacement of zinc atoms in sphalerite.