Free Astronomy Magazine November-December 2020

29 NOVEMBER-DECEMBER 2020 ATMOSPHERIC POLLUTION ized episodes may have played a non-neg- ligible role in the pollution of the atmos- phere even in more remote times. Some studies carried out in the last two decades have actually highlighted historical periods during which human activities seriously contaminated the air, and not just on a conti- nental scale. One of those periods began in 1532, with the defeat of the Incas by the conquis- tadors led by Francisco Pizarro. The occupiers began to massively ex- ploit the silver mines of some Peruvian and Bo- livian locations, start- ing the most significant industrial activity on that continent. The methods used by the Spaniards to extract silver from galena, the mineral that most commonly contains it, were first its melting in open furnaces (in- efficient and very polluting) and then its amalgamation with mercury. This second M ining in Po- tosí, work of 1596 by Theodoor de Bry. Cerro Rico, near the Bo- livian city of Po- tosí, was known as the “mountain that eats men.” Alongside, colo- nial drawings of furnaces for melting silver (huayras) in the Bolivian Andes.