Categories: Chemistry in History , News | 1 Comment
It seems the Andean civilisations really were the ancient kings of heavy metal. Not only were they adept at mining and working gold, but they also used vermillion – a pigment based on cinnabar (mercury sulfide) – to decorate ceremonial objects and the bodies of their dead elite.
An international team of researchers has looked at mercury deposits in lakes around Huancavelica in the Peruvian Andes, home of the largest deposits of mercuric ore in the New World. Unlike studies in the Northern hemisphere, where there is no real evidence of pre-industrial mining of mercury, the team found that Andean cinnabar mining – and the associated mercury pollution – dated back nearly 3000 years to 1400BC.
Colin Cooke, and colleagues from Canada, the US and Germany, were interested in looking at the origin, degree and form of mercury pollution in the Andes before and after colonisation by the Spanish in the 16th Century. They used sediment cores from three lakes and looked at the levels of cinnabar and non-cinnabar derived mercury at various timescales.
The record shows significant rises in the levels of mercury corresponding to the heights of the Chavín and Inca civilisations. During the Chavín era, cinnabar dust made up the vast majority of pollutant mercury, but later residues indicate that the cinnabar had been smelted to free the metal from its ore.
With the increased colonial demand for liquid mercury to use in amalgamation to purify silver and gold, mercury levels rose massively, with a much greater proportion being attributable to free mercury rather than cinnabar. The smelting of the ore in the area around the mines gave rise to high atmospheric concentrations of mercury, making it a dangerous place to work and earning it the nickname mina de la muerte (mine of death). Mercury residues also became much more widespread, rather than being concentrated around Huancavelica.
I think I’ll stick to emulsion paint for now…
Reference: C. A. Cooke et al, PNAS, 2009, DOI: 10.1073/pnas.0900517106