Prior to WMC Philippines (WMCP) discovery of the Tampakan copper-gold deposit in December 1992, no systematic exploration had been undertaken in the Tampakan district, although minor gold prospecting and panning had taken place since the 1960s with a resurgence in the mid 80s following the discovery of Diwalwal. The latter prompted a number of tenement applications by locals and assessments by several majors and local companies.

Reconnaissance exploration by WMCP within the Tampakan District commenced in November 1990, when company geologists were invited to the region by the Tampakan Group of Companies (TGC), a group of local mining claim owners in the district. Following preliminary field inspections and recognition of widespread advanced argillic and argillic alteration by Jens Balkau and Alan Buenavista, an Option Agreement was negotiated and signed by the parties on 25 April 1991.

Subsequent to the signing of this agreement, a comprehensive reconnaissance exploration program was initiated comprising multi-element regional stream sediment geochemical sampling and geological mapping. This initial phase of exploration was completed at the end of 1991 and defined a significant Cu-Au geochemical anomaly associated with advanced-argillic alteration around the headwaters of Pula Bato Creek in the Municipality of Tampakan, South Cotabato Province. This target was named the Gintong Bato anomaly and was selected for further detailed investigation.

Subsequent detailed grid-based multi-element soil geochemical, induced polarisation, electromagnetic and ground magnetic surveys, together with detailed geological mapping, defined a target for initial diamond drill testing with the first drillhole (TMPD1A) collared in December 1992. This first hole, which is located in the SW corner of the currently outlined deposit, was the discovery hole intersecting 143.6m @ 0.62% Cu and 0.48g/t Au from 51.32m and 153.23m @ 0.57% Cu and 0.14g/t Au from 342m. Eight diamond drillholes were subsequently completed in an initial exploration diamond drilling program with holes located on approximate 320m spaced traverses along a NNE-trending soil geochemical anomaly with a coincident anomalous IP response. All drillholes intersected significant and consistent intervals of low to moderate grade copper and gold mineralisation clearly indicating the discovery of a major copper-gold resource.

This discovery prompted WMCP to apply for an FTAA and secure other title in the area before commencing a systematic drillout of the deposit. The FTAA was granted in March 1995 covering an initial area of 896.69 Km2. By the completion of an advanced exploration drilling program on the deposit in September 1997, 85 diamond drillholes had been completed for a total of 31,474 metres. This led to an initial indicated and inferred geological resource estimate (non JORC) of 900Mt @ 0.75% Cu and 0.30g/t Au at a 0.5% copper COG.