Geophysical properties of zinc-bearing deposits

At present, most, if not oil zinc is being produced from the mineral sphalerite. With the exception of its piezoelectricity and in some cases its density, sphalerite has no salient physical properties to routinely allow its direct detection by geophysical methods. Although the mineral usually occurs with other sulfides, which do respond to various geophysical techniques, detection of zinc-bearing deposits is often difficult. In this paper, physical property measurements from numerous, mainly Australian, deposits are presented, together with examples from various geophysical surveys. The results ore used to suggest the most effective geophysical technique for the direct detection of the different types of zinc-bearing deposits. Induced polarisation is probably the most effective technique for unmetamorphosed sediment-hosted deposits and for carbonate-hosted deposits, whereas electromagnetics is usually the most appropriate method to use for volcanic-hosted deposits and for sediment-hosted deposits that Rave been strongly metamorphosed. Magnetics is the best technique for skarn and 'Cobar-style' deposits. However, it must be emphasised that usually more than one geophysical technique is required before a prospect can be considered to have been thoroughly explored.