Imaging galvanic couples in complex sulphide assemblages using multi-modal elemental and photocurrent microscopy

Modulated photocurrent mapping of electrical micro-junctions related to neighboring p-n zones in single or mixed phase sulphide assemblages can detect galvanic pairs which drive electrochemical reactions with overlaying fluids which is an important process for the petrophysics of geometallurgy. Understanding the role micro-junctions play in retarding or enhancing dissolution of an ore carrying sulphide requires imaging these couples near the surface and correlating them with both phase and elemental distributions. Here we apply multi-modal correlative imaging of a pyrite-sphalerite assemblage involving elemental mapping using electron and proton beam methods followed by laser beam induced current microscopy to reveal the spatial location of internal fields associated with micro-galvanic cells. This represents an important step in advancing electrochemical ore genesis models and further extends the toolkit for understanding and optimising mineral processing schemes based on specific geometallurgical footprints.