The Tampakan deposit of WMC (Philippines), Inc in Southern Mindanao is a high sulphidation deposit telescoped onto a porphyry copper deposit. Initial geological mapping of the area identified extensive alteration comprising grey silicification and clay alteration of the host andesites, presence in outcrop of fine grained chalcopyrite, bornite and molybdenite, complex brecciation, and correlation of lineaments defined from aerial photographs with zones of intense silicification. Stream geochemistry defined several areas of overlapping multi-element anomalism indicative of porphyry copper, high sulphidation and epithermal Au styles of mineralisation.

The most significant anomalism showed a dispersion train of 5 kms, with peak values of 7600 ppb Au and 870 ppm Cu. Soil geochemistry further defined areas of anomalism. Ground magnetics identified structural controls, consistent with air photo interpretation, of the alteration and mineralisation. Induced polarisation surveys carried out by McPhar mapped sub-horizontal PFE anomalies which when projected as various ‘depth’ slices correlate in many cases with areas of Cu-Au mineralisation. Diamond drill holes were sighted to test an interpreted sub-horizontal mineralised zone within massive silica and silica-clay breccia zones. Drill holes 1 - 5 were drilled either vertical or at an angle of 600 to horizontal and along the interpreted north-north-east trend of the mineralisation. All holes intersected significant widths (100 to 200m) of 0.8 to 1.0% Cu and 0.1 to 0.6g/t Au. Holes 6 and 7 were drilled to the east of the line of holes 1 - 5 and intersected similar widths and grade. A second phase of drilling was commenced in June 1995. In March 1998 WMC announced a resource of 900 million tonnes at 0.75% Cu and 0.3 g/t Au (at 0.5% Cu cut-off).