1. Exhausting the Sierra Madre: Mining Ecologies in Mexico over the Longue Durée

Abstract

The Cerro de San Pedro is the name of what used to be a small Mexican mountain. It is also the eponym of a small mining town perched in a highland valley overlooking the city of San Luis Potosí, Mexico. Today it is the object of a large-scale open-pit gold and silver mining project, one profoundly reconfi guring local topographies, hydrological systems, and the district’s geochemical composition. Every day over the past six years the New Gold mining corporation has detonated massive charges of ANFO, Geldyne, Powerfrac, and Pentex. The mountain of San Pedro is no longer. It has now been reduced to neat set of benches that contour around an ever deepening and enlarging pit. The excavated material is trucked out to leaching piles, where it is sprayed with a cyanide-water solution to fi lch out microscopic particles of gold, or it is dumped in piles of waste that fi ll the valleys and arroyos of the surrounding watershed. The impacts on local waters are tremendous. Aside from the acidifi cation and heavy-metal release that are contaminating the water, the pit is creating a massive well eff ect that is drawing in the region’s subterranean water fl ows. By plugging up drainages, the mine is obstructing the movement of surface water. The liners underlying the leaching pads are sealing off one of the regional aquifer’s most important recharge zones, and yet simultaneously the project draws in enough water from it to provision an estimated 50,000 people in the neighboring city of San Luis Potosí. This has long been the way with mining. Since the arrival of Spanish miners in 1592, the extraction of metals from the subsurface has chapter 1