by Michael Keller
The rural highlands farmers and herdsmen called campesinos who work the land near Bolivia’s Cerro de Potosí Mountain have had a problem for the last 468 years.
It was way back then when someone stumbling around this dry and dusty section of the Andes kicked over a rock on the mountain and found silver ore. A mine was built that fed the Spanish Empire’s thirst for the precious metal. It still operates today.
Those mining the mountain have slowly chipped away what became known as Cerro Rico—Rich Hill—and, after the silver ore started drying up, expanded their production to other valuable metals found in the ground there: copper, gold, iron, zinc, tin, lead, cadmium and chromium. More than 10,000 still travel down some 600 pitheads to make their pay underground.
The resulting environmental mess caused by metal contamination running out of the mines has made headlines for years. Dozens of toxic minerals spew out of mines, boreholes and tailing piles in the region’s wastewater discharge, including 161 tons of zinc, 157 tons of iron and more than two tons of arsenic that scientists have estimated flow out of just one study area every year. Some streams sampled around Potosí are as acidic as lemon juice from the runoff; others are as basic as milk of magnesia.