Both surface and underground geologic mapping has revealed many features in addition to those already recorded in the literature of the Baguio district. Geologic mapping has focused on formational units older than Miocene, when most mineralization in the district occurred.Results show that gold and possibly base metal mineralization preferentially occurs within a zone about 8 km wide and extending roughly north-south for tens of kilometers. The zone is bounded by an intrusive belt to the east and a volcanic belt to the west. Within this zone all known gold vein systems have been observed to occur in diamond-shaped shear blocks. The shear blocks are the result of pre-mineralization compressive stress that might have been periodically reactivated as orogeny progressed through time. This zone is very favorable for gold vein and base metal deposits.