Several geophysical experiments were performed over the Mariano Lake orebody before mining began, including surface self-potential methods, surface-to-hole induced-polarization methods, and reflection seismic methods. These geophysical techniques are interesting from an exploration point of view, and they also provide some data which relate to our conceptual model of this orebody. Currents generated in the productive formation by oxidation-reduction reactions do not generate measurable potential anomalies at the surface. Surface-to-hole induced-polarization measurements appear to be capable of detecting an oxidation-reduction front in the vicinity of an exploration borehole. Reflection seismic techniques can provide information concerning the paleostructure of the area.