Huancavelica: the American mercury that refined American silver
The cinnabar of Huancavelica, worked from 1564, gave Peru its own supply of the mercury that silver amalgamation consumed. The achievement has a measured price: an estimated 56,000 tons of mercury vapour, a labour draft that named the men it took, a disease the sixteenth century already called the illness of Huancavelica, and adobe walls contaminated still. And a counterpoint — a lake beside Potosí records more mercury from pre-Hispanic smelting than from the colonial process that replaced it.
Why this wins its question: The mercury half of the silver story is normally told either as a sentence of technical background — "the ore was refined by amalgamation" — or as an atrocity anecdote with no quantity attached to it. This object is the arithmetic: tons of mercury per ton of silver, tons of vapour per century, the share of a continental emissions budget, the ages and terms of the men the levy took, and the three colonial officials who wrote the symptoms down. It also carries the finding that most of the mercury pollution recorded beside Potosí predates the Spanish process, which is the fact a defensive account would omit and a hostile one would never look for. This corpus's own object on the patio process closes by stating that its two technical witnesses record nothing about the health of the workers; this is the object that supplies what that one could not.
Claims
Every assertion below is bound to registered sources and carries its own confidence. Weight them; do not treat the page as uniformly authoritative.
Colonial cinnabar mining and refining began at Huancavelica in 1564, and with a local source of mercury the amalgamation process was adopted to refine silver at Potosí in the early 1570s. The sequence matters: the American silver economy of the following two centuries rested on an American mercury deposit, not on shipments from Spain.
The scale of what that made possible is on the record in the same study: approximately 136,000 metric tons of silver produced in Latin America between 1550 and 1800, of which 18,000 metric tons came from Potosí city alone between 1574 and 1735.
The process consumed mercury at close to the weight of the silver it recovered. Robins and Hagan report estimates of the mercury consumed per pound of silver ranging from 1:1 to 2:1 — a function of ore quality and of the refiners' skill, both of which varied over time — and adopt 1.7 pounds of mercury per pound of silver for their calculations. Approximately 85 per cent of the mercury brought to Potosí was ultimately released as vapour into the atmosphere.
Between 1564 and 1810 the authors estimate approximately 17,000 metric tons of mercury vapour emitted from cinnabar smelting at Huancavelica and approximately 39,000 metric tons released during silver refining at Potosí — the two together more than 25 per cent of the 196,000 metric tons of mercury vapour emitted in all of Latin America between 1500 and 1800.
Those totals are estimates and their authors say so. The stated uncertainties are in the production records themselves, in smelter efficiency, in contraband production put at 25 to 30 per cent, and in the loss rates assumed during processing. They are the best published figures, not measurements.
The labour was compelled and its terms were specific. Men between 18 and 50 years of age from the areas surrounding Huancavelica and Potosí were subject to the mita levy and were required to work two months at Huancavelica or twelve months at Potosí.
The harm was recognised at the time, by Spaniards, in writing, and the study quotes them. José de Acosta, about 1590: if some smoke or vapour comes to the people who open the pots, "they get mercury poisoning and die, or remain in a very bad state or lose their teeth". Damián de Jeria in 1604 records a cough and a certain illness "called the illness of Huancavelica". Pedro de Oñate in 1629: "we well know and have seen … how terrible are the effects of mercury, as only in smelting … and treading … many are poisoned by mercury". A colonial administration that named a disease after the town it came from was not in ignorance of what the work did.
The exposure did not end with the colony. Widespread mercury contamination is still present in both towns, in ambient soil and in residences constructed of adobe brick — the material of the ordinary house being, in a mercury district, the medium that keeps the exposure going.
The counterpoint is measurable and it cuts against the simplest version of the story. A sediment core from Laguna Lobato, six kilometres east of Cerro Rico de Potosí, records mercury enrichment beginning as early as the twelfth century and peaking about 1250 AD at 2,000 ppb with a flux of 325 micrograms per square metre per year — roughly twenty and twenty-two times background — from indigenous smelting of silver-bearing ores in wind-drafted kilns fluxed with galena. After amalgamation was adopted the values fall but stay elevated, above 300 ppb and 80 micrograms per square metre per year, and the authors conclude that approximately 70 per cent of the total mercury pollution inventory in that sediment predates amalgamation.
The two findings are not in contradiction and should not be read as cancelling each other. The lake core is a local record of smelting near one Andean site and says nothing about total regional emissions; the emissions inventory is a regional estimate and says nothing about any particular lake. What the pairing does establish is that metallurgical mercury pollution in the Andes was not introduced by the Spanish, and that the colonial contribution was to change its scale, its geography and the labour system that bore it.
What is not evidenced here should be said plainly. Neither source read for this object is an administrative history of the Santa Bárbara mine: the crown's mercury monopoly, the price at which mercury was sold to the refiners, the proportion of mitayos to paid workers at the face, and the mine's own mortality registers do not appear in the pages read, and no figure of that kind is claimed here.