14 DAY TRIAL // Over the years, Peruvian lakes have shown archaeologists that the traces of pollution they contain were not generated only by modern-day industrial activities, but also by mining done by the Spanish, the Incas, and several other populations on these territories before them. A number of lakes around Peru have important traces of mercury on their floors, and they have offered investigators a complete picture of how the trade developed. Predictions derived from mercury concentrations are in perfect tune with the estimated history of the civilizations that inhabited the regions around what is now the Huancavelica area of Peru.
One specific mine, named Santa Barbara, was dubbed the mine of death (mina de la muerte) by the Spanish, as numerous slaves working there lost their life due to mercury poison, Nature News reports. All the populations that controlled the territory at some point, ranging from the Spanish to the Incas, and the Chavin before them, extracted precious cinnabar ore, or mercury sulphide. While the Europeans were using it to treat silver, the indigenous populations employed mercury to create paints and to decorate their bodies before battles or during ceremonies.
Researchers from the University of Alberta in Canada, led by expert Colin Cooke, analyzed mercury in sediment deposits on the bottoms of three lakes around the Santa Barbara area. These lakes were chosen specifically for the fact that they were located at various distances from the former mine. The analysis revealed that mercury concentrations were largest in the two nearest lakes around 1400 BC. “The onset of cinnabar mining at Huancavelica ca. 1400 BC places our lake-sediment records among the earliest evidence for mining and metallurgy in the Andes,” the researchers explain in the latest issue of the scientific journal Proceedings of the National Academy of Science (PNAS).
After the Chavin reached their peak, around 600 BC – with concentrations reaching ten times that of the background –, the amount of mercury dropped substantially until 1200-1450 AD, depending on the surveyed lake. When the Incas took over, they again lifted the concentrations to 50 times the background by 1550 AD. “Initially, when mercury mining starts in 1400 BC it's restricted to the area around the mercury mine. It's certainly clear once the Incas move into the region it goes up almost tenfold. The Incas are the big show, the Spanish are second to them but not by much,” Cooke adds.
“These mines were so heavily used during colonial times that any evidence of the early mining technology had been eliminated. When I read [the study] I thought 'this is so elegant.' People have used lake cores widely in order to look at vegetation change or as a proxy for climate change. This is the first time I've seen people use it to look at mining,” Yale University Anthropologist Richard Burger tells about the research.