The Philippines is one of the most richly endowed parts of the Southwest Pacific, with many porphyry copper-gold and epithermal gold-silver deposits scattered along the archipelago (e.g., Sillitoe and Gappe, 1984; Mitchell and Leach, 1991; Fig. 1). Chinese mining artifacts discovered in the Baguio and Masbate districts suggest that gold and silver mining dates back to at least the 14th century. Several placer gold mining regions were active during the Spanish regime (1521 to 1898; Bureau of Mines and Geosciences, 1986). Since World War II, gold and silver production has risen fairly steadily, from 2.0 t Au and 1.4 t Ag in 1946 to 37 t Au and 34 t Ag in 2009 (Bureau of Mines and Geosciences, 1986; Fig. 2). Between 2005 and 2009, the Philippines accounted for approximately 1.5 and 0.1 percent of global gold and silver production, respectively, when approximately 37 t Au and between 14 and 34 t Ag were produced each year (George, 2011; Brooks, 2011; Fig. 2). Fig. 1 A. Distribution of active copper, gold, silver, zinc, chromium and nickel mines in the Philippines, circa mid-2011. Modified from Philippines Mines and Geoscience Bureau, http://www.mgb.gov.ph/. B. Study site locations for this special issue. Fig. 2 Philippines gold and silver production (in tonnes) from 1910 to 2009, and copper production (in millions of tonnes) from 1947 to 2009. Data sources: Wu (1984), Bureau of Mines and Geosciences (1986), Lyday (1989), Edelstein (1994, 1999, 2004, 2011), Lucas (1994), Reese (1994), Amey (1999), Hilliard (1999), Brooks (2004 Brooks (2011) and George (2011). The first large-scale copper mining operations in the Philippines commenced at …