Paul Budd, Paul Lythgoe, Rona A. R. McGill, A. Mark Pollard, and Brett Scaife
Zinc isotope fractionation in liquid brass (Cu-Zn) alloy; potential environmental and archaeological applications (in Geoarchaeology; exploration, environments, resources, Pollard,)
Geological Society Special Publications (1999), 165 147-153

Abstract:
A preliminary study of zinc isotope fractionation in brass melting suggests that the process can be modelled by simple Rayleigh fractionation. Brass melting experiments at 1100 degrees C followed by quadrupole ICP-MS isotope ratio measurements of the resulting alloys suggest that the model is appropriate and that a useful approximation of the fractionation factor (alpha ) is 1.0064. The data indicate that the change in isotope ratio of the residual liquid alloy would be measurable for zinc losses by evaporation of more than about 30 wt.%. It is unlikely that measurements at the precision of the current study ( approximately 0.55 per mil amu (super -1) ) would be sufficient to distinguish between the two principal historical brass-making processes, although more precise measurement using a multi-collector ICP-MS probably would be. The experimental data also suggest that zinc vapour evolving during the evaporation of the first few per cent of the metal will be significantly fractionated ( approximately 1.5 per mil amu (super -1) ) with respect to the liquid. This might provide a basis to distinguish between environmental zinc from high-temperature industrial processes and that derived from natural and manufactured product sources.