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date: 23 April 2024

Potosí Minesfree

Potosí Minesfree

  • Kris LaneKris LaneDepartment of History, Tulane University


This article examines the long history of Potosí, Bolivia, home of the world’s most productive silver mines. The mines, discovered in 1545 and still active today, are discussed in terms of their geology, discovery, productivity, labor history, and technological development. The article also treats the social and environmental consequences of nearly five hundred years of continuous mining and refining.


  • History of Northern and Andean Spanish America
  • 1492–1824
  • Colonialism and Imperialism
  • Labor History

In 1545 a native Peruvian named Diego Huallpa discovered the richest silver deposit the world has ever known: the Cerro Rico de Potosí, high in the mountains of southern Bolivia. Huallpa had been working for a European overseer at the nearby mines of Porco, the main source of silver for the recently toppled Inca Empire. Spanish conquistadors rushed to Porco to stake claims by 1538, and in 1539 they established an administrative capital they called La Plata (today Sucre) at a lower and more comfortable altitude. It was while traveling between Porco and La Plata that Diego Huallpa was ordered to climb a red mountain, possibly known as Potoc’chi, in search of an Inca shrine or burial offering. Huallpa later testified that he reached the 15,800-foot (4820m) summit of this sacred peak where he found a huaca, or shrine. He carried some part of the huaca down the mountain, but as he descended a great gust of wind blew him down, and as his arm dug into the side of the hill he discovered pay dirt—rich silver ore, familiar from his work at Porco. Huallpa wrapped some of the precious material in his blanket and carried it off to Porco for assay.

Various legends arose around Diego Huallpa’s chance discovery of what became known as the Cerro Rico, or Rich Hill, of Potosí, but what is clear is that within a year of his “wind fall,” thousands of Spanish and indigenous prospectors, along with dozens of enslaved Africans, crowded into a makeshift camp at the mountain’s base and fought over claims staked in five major vein systems on the slopes above. There was the Centeno Vein, the Vein of the Flemings, the Tin Vein, La Veta Rica, and the Vein of Mendieta. Others would soon be uncovered and pursued deep underground. Native Andeans like Huallpa led the way.

Shortly the city of Potosí appeared, one of the world’s highest at over 13,200 feet (4060m) above sea level. The king of Spain, Carlos I, also known as Holy Roman Emperor Charles V, bestowed upon Potosí the special title of Imperial Villa (formally enacted in 1559) in recognition of its enormous yield of silver in a time of great need. From the start, taxes on Potosí silver helped bankroll the emperor’s many wars. Charles V’s four Habsburg successors, from Philip II through Carlos II, would rely on Potosí as well.

Potosí’s mines went through many cycles of boom and bust after 1545, yet amazingly they are still producing silver and other metals as of this writing (2015). It appears that the mountain’s hundreds of mines were never totally abandoned in the intervening centuries, making the Cerro Rico one of the longest continuously mined ore deposits on earth. In colonial times, Potosí’s overall production rose and fell three times, peaking in 1550, 1592, and 1795, with the lowest point reached in 1712, the only year in which under a million pesos were declared. The most significant revival of the mines after Bolivian independence in 1825 occurred after 1900, when the Cerro Rico’s substantial tin deposits were first exploited using modern drilling equipment and dynamite. Potosí’s current boom dates to the early 2000s, when Asian industrialization began to drive up global commodity prices. Prices have fluctuated, but no one knows when the next bust will come.


According to recent studies, the Cerro Rico or “Rich Hill” of Potosí consists of a dome of volcanic material that spewed up through a narrow dike some fourteen million years ago and flowed out over old sedimentary deposits. Fossil leaves have been found around the western margins of the Red Mountain. The dome itself settled, cooled, and cracked, and in the course of several active episodes occurring not long after the initial eruption, superheated fluids pushed up through the fissures from far below, cooling and precipitating minerals of various kinds, many of them metallic. Near the center of the mountain, where temperatures were highest, tin minerals formed in abundance. Farther out from the core, where temperatures were lower, silver, zinc, lead, iron, copper, and other metals precipitated in various combinations, along with quartz, calcite, and other non-metals.

Episodes of enrichment from below were followed by a steadier process of oxidation, erosion, and “trickle-down” enrichment from above, making the upper slopes of the mountain, just beneath a hard, red cap or crest of silica, some of the richest and most easily exploited silver deposits on the planet. These generally reddish, oxidized ores near the surface, some containing over 40 percent silver, fueled Potosí’s initial bonanza. Some oxidized ores extended several hundred meters down. Miners dug shafts in pursuit of steeply inclined veins, which eventually yielded only dark-grey, harder ores of lower grade, many of them containing refractory sulfur compounds. These ores were relatively abundant down to a certain level inside the Cerro Rico, but extracting them grew increasingly costly, especially after miners perforated the water table, which rose like a dome under the mountain. Pumping flooded mines was a never-ending chore, which led to the cutting of horizontal drainage tunnels as early as 1556.


The one region of the Americas where mining and metallurgy were most developed prior to European arrival in the 16th century was the Andean Cordillera of South America. The Incas inherited an ancient mining and metallurgical tradition, and the Spanish took full advantage of this fact after conquest began in 1532. Local peoples produced not only gold and silver ornaments and utensils but also copper and arsenical bronze tools. What this meant was that indigenous prospectors, miners, smelters, and smiths were vitally important in the first four decades after the Spanish conquest, and in many parts of the old Inca Empire they continued to be the most significant silver producers—in both the technical and labor senses—long afterwards. The main Spanish interventions were two: (1) the introduction of iron and steel tools, which greatly facilitated ore extraction and crushing, and (2) the introduction of mercury amalgamation, a key refining method. Iron tools arrived in Potosí soon after the conquest, whereas mercury amalgamation took root only after 1572. Along with amalgamation came German-style, water-powered stamp mills.

Potosí’s first mines were little more than open pits from which indigenous workers—most of them, like Diego Huallpa, dependents of Spanish or Portuguese overlords—chipped out ore with iron bars. Most native Andean mineworkers in these early years were called indios varas, or “Indians by the yard,” a reference to the number of yards of vein they worked. Ores produced by the indios varas were sorted by grade, carried down the mountain by either indigenous workers or llamas, and distributed to indigenous refiners.

Native Andeans had developed a type of furnace made from stone and clay known as a huayra, borrowing the Quechua word for wind. According to early sources, over six thousand huayras were constructed on the hills and ridges around Potosí, lighting up the night like so many devotional luminaries as they took advantage of daily or katabatic mountain winds. They had no bellows or other moving parts. The huayras were highly efficient smelters of high-grade silver ores, but they required fuel, a scarce commodity at these altitudes. Most huayras burned llama dung and a type of heavy, high-altitude moss called yareta.

During Potosí’s first boom-and-bust cycle in the late 1540s to 1560s, indigenous miners and refiners, the so-called huayradores, prevailed. Native Andean mineworkers paid their Spanish overlords a tribute or agreed-upon quota in silver, and some native smelters grew rich as subcontractors. Many mineworkers were allowed to keep silver produced beyond their agreed-upon quota, which paid for basic comforts and in some cases permitted wealth accumulation. Other native Andeans specialized in the supply trade, also becoming modestly wealthy as pack-animal teamsters or labor recruiters. The indigenous-dominated system of silver production worked as long as the Cerro Rico yielded oxidized, readily smelted ores. These ran short within a decade of discovery, bringing about Potosí’s first decline.

The early silver mines of Mexico had undergone similar cycles of boom and bust beginning in the 1530s, prompting innovators to come up with new refining methods capable of processing large quantities of low-grade ore. One such innovator was a merchant from Seville named Bartolomé de Medina. Working near the mines of Pachuca, not far from Mexico City, Medina adapted a method he apparently learned of in Spain from visiting Germans. In 1554, he developed what later became known as the patio process, an open-air system of beneficiation that mixed finely ground silver ore with mercury and other reagents. These were stirred periodically in the course of several weeks. The resulting amalgam was then washed and fired, driving off the volatile and toxic mercury and yielding ingots of nearly pure silver.

Medina’s mercury-based refining process was adapted to the ores and conditions of Potosí in 1572, during the visit of Peru’s most famous viceroy, Francisco de Toledo. To work on a large scale, the construction of multiple crushing mills was required. Toledo ordered thousands of native workers to construct dams in the neighboring Kari-Kari mountains to supply water for dozens of new mills, or ingenios. It was a huge and revolutionary project, and it soon returned Potosí to great wealth. As will be seen, Toledo also organized a controversial draft labor system for the mines and mills known as the mita, from the Quechua word mit’a, or “turn.” Massive mercury deposits had only recently been discovered in 1563 at Huancavelica, in the high Andes east of Lima. Toledo organized a mita for these mines as well. Choking miners and their families with toxic dust and fumes, it became known as the “death mita.” Viceroy Toledo’s drastic overhaul of Potosi and Huancavelica ended the age of Andean-dominated mining and commerce.

Potosí’s underground innovations included the cutting of horizontal tunnels or adits (in Spanish, socavones) to drain and provide easier access to steeply inclined vein systems. The earliest socavones predate the arrival of Viceroy Toledo in the 1570s; one pioneered by the Florentine mine owner Nicolás de Benino, a member of the Medici family, was several hundred yards long by the time Toledo arrived. Many more adits were cut or attempted after Toledo left in 1575, but not all were carefully planned. It proved more difficult than expected to “aim” a tunnel at a distant vein system. A report from 1585 listed over a dozen socavones, some in progress, others abandoned. Adits were a major investment since they were cut through mostly non-productive rock, and the time it took to reach ore bodies could exceed twenty years. Benino’s great socavón took twenty-nine, and he had to form a company of investors. A standard adit cost as much as the construction of a sizeable church.

Another innovation was the use of black powder for blasting. By contrast with horizontal adits, which appeared within a dozen years of Potosí’s discovery, black powder blasting was much slower to be adopted, showing up only in the 1670s. Despite the late date, this was only a few decades after European miners began to routinely use powder for excavation, particularly in southern Germany. Blasting saved labor for workers used to chipping hard rock by hand, but it also increased the dangers of rock fall and inhalation of particulates, which could lead to silicosis and other lung diseases. Some mineworkers nevertheless developed great skill in drilling and placing charges, and they soon commanded higher than average wages.

Local residents of Potosí also pursued innovations in refining, helping to offset the inevitable downturns caused by the exhaustion of rich ores. The priest Alvaro Alonso Barba worked for many years in the early 1600s developing new refining processes for the ores of the Cerro Rico as well as for silver ores produced in dozens of more distant mining zones in the city’s hinterland. Steeped in alchemical theory, Barba nevertheless embraced experimentation and openly questioned authorities in a way that European contemporaries such as Francis Bacon might have appreciated. He was fully representative of the “New Science” of the 17th century, and he cited the work of his contemporary, Galileo Galilei, on the moons of Jupiter. Barba’s great work, The Art of Metals, first published in Spanish in 1640, was soon translated into English, German, and French and was reprinted numerous times until the end of the 18th century.

It was in the early 18th century that Spain’s Bourbon kings wondered what had gone wrong in Potosí. They blamed local mine owners and native Andeans for their alleged ignorance, assuming that all Potosí needed to return to its former glories was updated technologies and a few tax incentives. Much taken by Enlightenment science, Spain’s Bourbon administrators organized a series of technical missions to the mines of the Americas in hopes of reviving them with the latest tools, theories, and technologies.

A technical mission headed by Baron Thaddeus von Nordenflicht, a Polish Protestant, reached Potosí in 1789. Many mine and mill owners hoped for a miracle, but it soon became clear that the barrel-type amalgamation machines that Nordenflicht promoted, designed by the Austrian engineer Ignaz von Born, were difficult to build in Potosí, which lacked “high-spec” craftsmen, as well as trained engineers and high-quality steel. One of the Born machines produced positive results, but it quickly proved too expensive to maintain. Students at Potosí’s mining academy (founded a decade earlier, in 1779) were instructed to keep reading Barba’s Art of Metals. Barba’s work was hardly new, but like Born he had elaborated a sophisticated, heated amalgamation method for refining refractory and low-grade ores.

When British speculators arrived in Potosí with Bolivia’s independence in the early 1820s, indigenous mineworkers were still hand cutting ore, shouldering it in sacks, and sending it down the hill on the backs of llamas to a dozen or so water-powered stamp mills for trituration. Mercury amalgamation, aided by salt and other locally available reagents, was still the typical refining method, barely altered from the days of Francisco de Toledo. The venerable dams and canals that supplied the crushing mills with waterpower were periodically repaired, but not much improved. Primitive as this archaic, almost medieval system was, it worked. British attempts to introduce new technologies in this first round failed. The mine owners’ main concerns, as always, were cheap labor and cheap mercury, not new-fangled technologies. Beginning in the late 18th century, when Huancavelica’s mines failed to yield and European supplies were cut off by naval warfare, mercury became Potosí’s biggest problem. Silver production declined steadily through the early 19th century.

Relief came after 1848, when massive mercury deposits were discovered in California near San José just before the famous gold strike at Sutter’s Mill. California mercury partly revitalized Potosí silver production. Strikes in Potosí’s northern hinterland at Colquechaca and Huanchaca were significant boons as well. But it was not until the turn of the 20th century that Potosí’s mine owners introduced major new mining and refining technologies. These were made possible with the construction of rail lines, which linked mining towns of the Andean highlands like Oruro and Potosí to the Pacific coast. Along with the rails and trains and telegraph lines, all heavy equipment had to be imported from Europe or the United States. Local steel production was still a dream.

Global industrial growth and abandonment of the silver standard in many countries after 1891 shifted interest from silver to tin, zinc, and other base metals, which Potosí’s Cerro Rico—and many other mining districts in Bolivia—possessed in abundance. Tin ores were extracted using pneumatic drills and dynamite, soon aided by electric ore carts and trams. The story of Bolivian tin, intertwined with that of the great tin baron Simón Patiño, falls outside the scope of this entry, but technological changes in Patiño’s tin mines, most of them in the vicinity of Oruro, cascaded into Potosí’s Cerro Rico.

In part a legacy of Bolivia’s state mining company, the now near-defunct COMIBOL, founded in 1952, basic pneumatic technology still prevails in most of the Cerro Rico’s cooperatively run mines as of this writing, although since about the year 2000 several multinational mining conglomerates have begun to exploit and refine large amounts of low-grade surface ore. Since the Cerro Rico remains an iconic symbol of Potosí and even of Bolivia, there has been a strong push in recent years to preserve the summit and the shape of the great red cone despite considerable subsidence and partial collapse. Yet attempts to shutter the mines of the Cerro Rico for the sake of patrimony have been firmly resisted by Potosí’s small-scale miners, refiners, and suppliers.


Underground mining is hard and dangerous work, and mines are frequently located in remote and inhospitable places where few humans wish to live. Only the prospect of personal bonanza or high wages has tended to induce people to try their hand at mining, whether in ancient or recent times. The ancient Romans in Iberia and elsewhere assumed that mine work required armies of condemned criminals; it would not be done voluntarily by peasants or other free people. Mine work under the Incas may have been somewhat less onerous, but it was probably not a sought-after job.

Coerced mine labor persisted after the Spanish conquest, although with some rubs. After Potosí’s discovery in 1545, Spanish conquistadors demanded that conquered Andeans do the work of mining and refining for them; brute force played no small part in the district’s development. Yet, almost paradoxically, surviving records suggest that there were enough benefits to be had from silver mining, at least at first, to induce many Spaniards and Andeans to work together. Force was not always needed, especially in a world of limited options.

A result of pragmatism rather than good will, there arose many variations on the early cooperative extraction model. To pick an example, Diego Huallpa, the Cerro Rico’s discoverer, was a yanacona from Jauja, Peru, working for a minor Portuguese conquistador. Yanaconas were mostly men unattached to their home villages, and many served as personal servants to Europeans. Others hired themselves out and some became skilled urban artisans. Village Andeans held in encomienda were also among the first workers in Potosí’s mines; their forced migrations were technically illegal, and some were illegally rented out by Spanish overlords to fellow mine owners. Before long, however, it appears that native Andeans who were not vassals of Spaniards or other Europeans began to work for themselves or for others in exchange for wages—usually a share of ore or refined silver. In the 18th century ore sharing was known as kajcheo, and independent kajchas formed a kind of syndicate and battled with mine owners and crown officials. The rise of free labor in mining districts such as Potosí should not surprise us, but this type of arrangement was always overshadowed by the mita.

The Potosí mita was not invented by Viceroy Francisco de Toledo, but he was responsible for formalizing and expanding it in the early 1570s. A massive labor subsidy for Spanish mine and mill owners and a major cause for indigenous population decline in a large portion of the Andes, the mita proved controversial from the start. Native Andean men aged eighteen to fifty from as far away as the outskirts of Cuzco were drafted periodically to work in Potosí’s mines and refineries. Over twelve thousand mita workers, or mitayos, were expected to be in Potosí at any given time, and records show that for several decades such numbers were sustained.

Family members accompanied mita workers in their long migrations, turning Potosí into one of the most populous cities in the world and certainly the largest in the Americas at over 120,000. But by the 1620s, if not before, many mines in the Cerro Rico began to play out, and new finds in Oruro, Cailloma, Chayanta, San Antonio del Nuevo Mundo, and other distant sites drained away both workers and mine owners. Potosí’s powerful mill owners, known as asogueros, nevertheless clung to their crown-mandated mita allotments, demanding cash payment in lieu of labor service. For many mine owners and asogueros the mita turned into a cash subsidy, a disincentive to mine and refine silver.

Despite the repeated and sometimes desperate attempts of many priests and other critics, the Potosí mita was not abolished until the end of colonial times. Once formalized by Viceroy Toledo in the early 1570s, it proved nearly impervious to reform. By the time Simón Bolívar reached Potosí in 1825, the Potosí mita was seen as the single most potent symbol of more than two-and-a-half centuries of Spanish oppression. Bolívar climbed to the top of the Cerro Rico to declare this age of horror over. Unfortunately, the plight of Bolivia’s native population did not end with the Liberator’s decree. Native Bolivians would continue to mine the wealth of a nation that for many more decades treated them as subjects rather than citizens. Even the mita was revived briefly after independence, although it ended in 1832.

Foreign engineers became a more common sight in Potosí after Bolivia’s independence in 1825, but the vast majority of mineworkers continued to be indigenous men from the highlands, most of them Quechua speakers. Both Quechua-and Aymara-speaking miners developed a culture peculiar to mining life, above and underground. Although frowned upon by Bolivian and foreign mine owners and overseers, not to mention Potosí’s parish priests and later missionaries, native Andean miners devoted considerable time and energy to placating the ruling spirit of the underworld, a diabolical figure known as El Tío.

A trickster of sorts, El Tío is said to aid miners who respect him by making regular offerings of liquor, tobacco, and coca leaves, and to punish those who ignore him or remove rich ores from the mines without proper thanks. Ritual offerings to El Tío are complemented by periodic sacrifices to Mother Earth, or Pachamama, just outside mine entrances. Llamas are typically slaughtered and their blood used to paint the mine threshold, ore carts, and other mining equipment. The prevailing ethic among native Bolivian miners in Potosí and elsewhere is to not upset a fragile balance, a reciprocal agreement between humans who need minerals to subsist and spirits who need offerings and sacrifices to continue providing.


Few colonial products were of greater interest to the king of Spain than silver and gold. Legally, all mineral deposits within the Spanish realm were royal patrimony; the king simply allowed his enterprising subjects to exploit precious metals in exchange for a one-fifth share. Potosí’s royal fifth, or quinto real, was a major source of crown revenue from 1545 to the end of the colonial period, although it dropped off substantially after 1650. We will never know exactly how much silver Potosí produced, but we have a useful guide in the form of quinto records, which date to just after discovery. It was a major offense to dodge quinto payments, particularly for large producers, but a significant percentage of silver clearly went untaxed. Reports of raw ingots being smuggled to Buenos Aires or the Pacific coast were common throughout colonial times. Even so, the scale of such contraband trading probably never reached the level of registered production.

According to colonial tax records, which span the years 1545 to 1823, Potosí produced some 22,695 metric tons of silver. This is only a baseline amount, yet it constitutes a huge share of global silver production for this period. Between 1545 and 1650, Potosí’s long heyday, the Cerro Rico alone produced—according to official records—more silver than all of Mexico, which boasted a number of famous mining districts. Only in the 18th century did Mexico’s richest silver mines really take off, leaving Potosí and the mines of Peru and Bolivia far behind in terms of total production. Statistics are less clear for the post-independence period, but the Cerro Rico of Potosí has proved to be one of the most long-lived of the world’s silver mining sites.

Viceroy Toledo bestowed upon Potosí another institution worthy of mention: a royal mint. Founded in 1575, the Casa Real de la Moneda began coining silver on a small scale, relying on a mix of drafted indigenous and enslaved African workers. By the early 17th century, the mint had expanded considerably. Subcontractors leased workshops within the mint and filled them with enslaved Africans, mostly men from Angola and Congo, who prepared coin blanks by hand. By 1640, over 150 enslaved workers were producing approximately five million “pieces of eight,” or silver pesos of about an ounce each, per year. By the late 1640s much of Potosí’s registered, mined silver was being coined. In fact, coin production was climbing steeply as mine production crashed. Something was clearly amiss.

As early as 1641, merchants in Antwerp and Genoa reported that coins bearing the Potosí mintmark were often below standard fineness. By the late 1640s Potosí coins were universally loathed, and the Spanish crown dispatched a former Inquisitor to fix the problem. Arriving in the Villa Imperial in late 1648, Dr. Francisco de Nestares Marín set about cleaning up the mint and punishing the culprits. In early 1650 he had the main defrauder, a silver merchant named Francisco Gómez de la Rocha, executed on the mint grounds. The mint’s corrupt assayer soon followed. It took nearly a decade to restore confidence in Potosí coinage, and the disruption caused by the mint fraud and its aftermath was seen as the death knell for the Imperial Villa. It is true that Potosí’s decline was not reversed for another century after the great mint fraud of the 1640s.

Potosi’s mines were revived briefly in the first years of the 18th century, partly in response to French merchant interest during the 1703–1713 War of the Spanish Succession, but a disease epidemic in 1719–1720 proved disastrous, wiping out both workers and potential customers for imported goods. Anxious for revenues, the Spanish crown finally reduced Potosí’s quinto to a tenth in 1736, stimulating production. Mercury supplies were also improved and prices lowered by the crown, and in time credit institutions were established to aid mine owners.

In 1776 Potosí’s new mint, the imposing, million-peso Casa Real de la Moneda, now one of Bolivia’s most famous museums, opened to great fanfare. It was hoped that the new building, outfitted with the latest money manufacturing technology, would stimulate the mines. To some degree it did so, but not nearly as much as officials in Spain had hoped. Even so, the Royal Mint continued to operate long into the republican period, its equipment updated with the arrival of railroads.

Global Connections

Given its extraordinary productivity, Potosí was rightly regarded the “treasury of the world,” at least for a time. There is no question that the Cerro Rico alone provided a considerable boost to the world’s currency supply. In early modern times silver and gold were the most widely accepted forms of money, and this meant that kingdoms, empires, and principalities from England to China all desired streams of precious metals, both to add glamour to their courts and to expand their realms through warfare.

Merchants, too, needed precious metals to move commodities from one realm to another, and to pay off investors in risky overseas commercial ventures. Potosí silver, in bar and in coin, lubricated global trade and enriched dozens of monarchs in equal measure. Historians have shown that a large portion of Potosí silver ended up in China, and a smaller but still substantial portion landed in India. These Asian kingdoms produced some of the world’s most valuable commodities, both raw and manufactured, and European merchants found that only American gold and silver was accepted as payment. Even so, the king of Spain, despite his considerable debts, was greatly envied by Asian monarchs for possessing such a legendary silver mountain.

The Imperial Villa of Potosí was also a global marketplace in its own right. Aside from consuming a huge quantity of imported iron and steel, most of it from the Basque region of Spain, Potosinos purchased vast amounts of textiles from Europe, China, and the Indian subcontinent. Potosí silver also paid for enslaved Africans, who were brought from all parts of West and West Central Africa. Africans, especially women, worked in almost every Potosí household of note by 1600; even rich artisans and some indigenous chieftains owned slaves purchased with silver.

Regional Andean or South American products included indigenous textiles, hats, and shoes from Cuzco, Quito, and elsewhere. Wine initially came from southern Spain, but by the 1580s much was produced in warm valleys to the east, south, and west. One of the most lucrative of all imports to Potosí, coca leaves came from the lowlands east of Cuzco, and later from the Yungas of La Paz. Other products that fetched high prices in Potosí included yerba mate from Paraguay, mules from northern Argentina, and sugar from hot valleys such as Mizque. Even lowly llama dung, so desperately needed for fuel, fetched high prices.

Mining and the Environment

Mining is an inherently destructive activity, and even without mercury amalgamation silver mining is itself a producer of numerous toxic byproducts. Mines disrupt subterranean water flows, and the water that comes out of mines almost always fouls streams and upsets pH balance. More toxic still is the runoff from refineries, where mercury, salt, and other solvents are typically added and rarely filtered. Little has changed since colonial times. Burst sedimentation ponds around Potosí have fouled the Pilcomayo and other rivers as recently as 2014.

In colonial times the vaporizing of mercury after amalgamation was probably the most insidious form of mining-related pollution, as mercury vapor was invisible and could be borne by the wind. For centuries, it condensed and settled over large parts of the city of Potosí and its environs, fouling soils, food, clothing, cooking gear, and practically everything else. Breathing mercury vapor was known to be highly hazardous at the time, and the proverbial saying for “scared to death” was “shaking like a victim of mercury poisoning” (temblando como un azogado). Other major hazards came from lead, which was used as a flux in silver smelting, and zinc, which occurs alongside silver in sulfide ores.

The environmental effects of Potosí’s long history of silver mining and refining go far beyond immediate toxins like mercury, zinc, and lead, and the extent of the damage is difficult to measure. Deforestation is a case in point. The demand for fuel and construction materials both above and underground led to deforestation even at great distances from the Cerro Rico. Colonial observers commented on this from the earliest days of bonanza. The nearer hinterland was immediately stripped of brush, ichu grass, and the soil-stabilizing yareta moss. Overgrazing likely resulted as well, despite the fact that llamas are well adapted to highland environments. In short, the environmental costs of Potosí’s enormous productivity remain nearly impossible to calculate.


“Worth a Potosí” was a catchphrase when Miguel de Cervantes wrote his great two-part novel Don Quixote in the first years of the 17th century. For a time it was true; there were no precious metals mines in the world to compete with those of the fabulous Cerro Rico, “treasury of the world.” The mines of Potosí also prompted centuries of Spanish soul-searching thanks largely to the well-documented horrors of the mita. The Cerro Rico seemed to epitomize the Spanish abuse of native Americans and despoliation of the Americas, and calamities such as a great flood in 1626 and the epidemic of 1719 were seen as just punishments by an angry God. The terms of argument have shifted over the years, but the strangely resilient mines of Potosí continue to be seen as a moral testing ground for Bolivians and others as of this writing.

Discussion of the Literature

The history of Potosí has been polemical since its discovery in 1545. Many early scholars focused on the development of the mita, or draft labor system formalized by Viceroy Francisco de Toledo in the early 1570s. Some were surprised to find a high proportion of free workers in the records. Aside from labor, the main topic of interest to pioneer scholars was overall production—using tax records to estimate gross silver output. Other scholars focused on the development of mining and refining technology, and others on Potosí’s role in developing long-distance trade networks. Since the 1980s, scholars have shifted away from labor, gross production, and technical matters to focus on mining culture, urban development, women’s lives, and the environmental impacts of mining and refining.

Primary Sources

Published primary sources include: José de Acosta, Natural and Moral History of the Indies, edited by Jane E. Mangan (Durham, NC: Duke University Press, 2002); Bartolomé Arzáns de Orsúa y Vela, Historia de la Villa Imperial de Potosí, 3 volumes, edited by Lewis Hanke and Gunnar Mendoza (Providence, RI: Brown University Press, 1965); Bartolomé Arzáns de Orsúa y Vela, Tales of Potosí, edited by R. C. Padden, translated by Frances López-Morillas (Providence, RI: Brown University Press, 1975); Alvaro Alonso Barba, Arte de los Metales (Potosí, Bolivia: Editorial Potosí, 1967); Hiram Bingham, Across South America: An Account of a Journey from Buenos Aires to Lima by way of Potosí (Boston: Houghton Mifflin, 1911); Pedro de Cieza de León, The Discovery and Conquest of Peru (Seville, Spain: 1554–1556); Marcos Jiménez de la Espada, Relaciones Geográficas de Indias—Peru, Biblioteca de Autores Españoles 183 (Madrid: Atlas, 1965); Pedro de León Portocarrero, Descripción del virreinato del Perú, edited by Eduardo Huarag Alvarez (Lima: Editorial Universitaria, 2009 [bilingual ed., orig. Portuguese ms. c.1620]); García de Llanos, Diccionario y maneras de hablar que se usan en las minas y sus labores en los ingenios y beneficios de los metales (1609) (La Paz: Banco Central de Bolivia, 1983); Juan Matienzo, Gobierno del Perú, edited by Guillermo Lohmann-Villena (Paris and Lima: IFEA, 1967); Fray Diego de Ocaña, Viaje por el Nuevo Mundo: de Guadalupe a Potosí, 1599–1605, edited by Blanca Lopez de Mariscal and Abraham Madroñal (Madrid: Iberoamericana, 2010); Enrique Otte, Cartas privadas de emigrantes a Indias, 1540–1616, 2d edition (Mexico City: FCE, 1996); Edmond Temple, Travels in Various Parts of Peru, including a Year’s Residence in Potosí, 2 volumes (Philadelphia: Carey & Hart, 1833); José María Vargas, Fr. Domingo de Santo Tomás, defensor y apostol de los indios del Perú: Su vida y sus escritos (Quito, Ecuador: Editorial Santo Domingo, 1937); and Antonio Vazquez de Espinosa, Compendium and Description of the West Indies, translated by C. U. Clark (Washington, D.C.: 1942).

Further Reading

  • Absi, Pascale. Los ministros del diablo: El trabajo y sus representaciones en las minas de Potosí. La Paz, Bolivia: IFEA, 2009.
  • Assadourian, Carlos Sempat. “La producción de la mercancía dinero en la formación del mercado interno colonial: el caso del espacio peruano en el siglo XVI.” In Ensayos sobre el desarrollo económico de México y América Latina (1500–1975), edited by Enrique Florescano, 223–292. Mexico, DF: FCE, 1979.
  • Assadourian, Carlos Sempat. El sistema de la economía colonial. El mercado, interior regiones y espacio económico. Mexico City: Editorial Nueva Imagen, 1983.
  • Bakewell, Peter J. “Registered Silver Production in the Potosí District, 1550–1735.” Jahrbuch fur Geschichte von Staat, Wirtschaft und Gesellschaft Lateinamerikas 12 (1975): 67–103.
  • Bakewell, Peter J. “Technological Change in Potosí: The Silver Boom of the 1570s.” Jahrbuch fur Geschichte von Staat, Wirtschaft und Gesellschaft Lateinamerikas 12 (1977): 60–77.
  • Bakewell, Peter J. Miners of the Red Mountain: Indian Labor in Potosí, 1545–1650. Albuquerque: University of New Mexico Press, 1985.
  • Bakewell, Peter J. Silver and Entrepreneurship in Seventeenth-Century Potosí: The Life and Times of Antonio López de Quiroga. Albuquerque: University of New Mexico Press, 1988.
  • Ballesteros Gabrois, Manuel. Descubrimiento y fundación del Potosí. Zaragoza, Spain: Delegación de Distrito de Educación Nacional, 1950.
  • Barnadas, Josep M. “Una polémica colonial: Potosí, 1579–1684.” Jarbuch fur Geschichte von Staat, Wirtschaft un Gessellschaft Lateinamerikas 10 (1973): 16–70.
  • Brading, David, and Harry Cross. “Colonial Silver Mining: Mexico and Peru.” Hispanic American Historical Review 52.4 (November 1972): 545–579.
  • Brown, Kendall W. A History of Mining in Latin America from the Colonial Era to the Present. Albuquerque: University of New Mexico Press, 2012.
  • Buechler, Rose Marie. The Mining Society of Potosí, 1776–1810. Syracuse: Syracuse University Press, 1981.
  • Cobb, Gwendolin B. “Potosí and Huancavelica: Economic Bases of Peru, 1545–1640.” PhD diss., University of California, Berkeley, 1947.
  • Cobb, Gwendolin B. “Supply and Transportation for the Potosí Mines, 1545–1640.” Hispanic American Historical Review 29.1 (February 1949): 25–45.
  • Cole, Jeffrey. The Potosí Mita, 1573–1700: Compulsory Indian Labor in the Andes. Stanford, CA: Stanford University Press, 1985.
  • Cooke, Colin A., et al. “Pre-colombian Mercury Pollution Associated with the Smelting of Argentiferous Ores in the Bolivian Andes.” Ambio 40.1 (February 2011): 18–25.
  • Craig, Alan K., and Robert C. West, eds. In Quest of Mineral Wealth: Aboriginal and Colonial Mining and Metallurgy in Spanish America. Geoscience and Man 33. Baton Rouge: Louisiana State University Press, 1994.
  • Crespo Rodas, Alberto. La guerra entre vicuñas y vascongados: Potosí, 1622–1625. La Paz, Bolivia: Colección Popular, 1969.
  • Cunietti-Ferrando, Arnaldo J. Historia de la Real Casa de Moneda de Potosí durante la dominación hispánica, 1573–1652. Buenos Aires: Pellegrini, 1995.
  • Cunningham, C. G., et al. “The Age and Thermal History of Cerro Rico de Potosí, Bolivia.” Mineralium Deposita 31 (1996): 374–385.
  • Dressing, David. “Social Tensions in Early Seventeenth-Century Potosí.” PhD diss., Tulane University, 2007.
  • Eichmann, Andrés, and Marcela Inch C., eds. La construcción de lo urbano en Potosí y la Plata (siglos XVI–XVII). Sucre, Bolivia: Ministerio de Cultura de España/Archivo y Biblioteca Nacionales de Bolivia, 2008.
  • Glave, Luis Miguel. Trajinantes: Caminos indígenas en la sociedad colonial, siglos XVI/XVII. Lima: Instituto de Apoyo Agrario, 1989.
  • González Casasnovas, Ignacio. Las dudas de la corona. La política de repartimientos para la minería de Potosí (1680–1732). Madrid: CSIC, 2000.
  • Hanke, Lewis. The Imperial City of Potosí: An Unwritten Chapter in the History of Spanish America. The Hague: Martinus Nijhof, 1956.
  • Hausberger, Bernd. “La guerra de los vicuñas contra los vascongados en Potosí y la etnicización de los vascos a principios de la edad moderna.” In Excluir para ser. Procesos identitarios y fronteras sociales en la America hispánica (siglos xvii–xviii), edited by Christian Büschges and Frederique Langue, 23–57. Frankfurt: Vervuert, 2005.
  • Helmer, Marie. Cantuta: Recueil d’articles, 1949–1987. Madrid: Casa de Velázquez, 1993.
  • Kindleberger, Charles P. Spenders and Hoarders: The World Distribution of Spanish American Silver, 1550–1750. Singapore: Institute of Southeast Asian Studies, 1989.
  • Klein, Herbert. A Concise History of Bolivia. 2d ed. New York: Cambridge University Press, 2011.
  • La minería hispana e iberoamericana. Contribución a su investigación histórica. Vol. 1, Ponencias del VI Congreso Internacional de Minería. León, Spain: Cátedra de San Isidoro, 1970.
  • Lohmann Villena, Guillermo. Las minas de Huancavelica en los siglos XVI y XVII. Seville, Spain: EEHA, 1949.
  • López Beltran, Clara. Estructura económica de una sociedad colonial: Charcas en el siglo XVII. La Paz, Bolivia: Centro de Estudios de la Realidad Económica y Social, 1988.
  • Mangan, Jane E. Trading Roles: Gender, Ethnicity, and the Urban Economy in Colonial Potosí. Durham, NC: Duke University Press, 2005.
  • Mills, Kenneth. “Diego de Ocaña’s Hagiography of New and Renewed Devotion in Colonial Peru.” In Colonial Saints: Discovering the Holy in the Americas, 1500–1800, edited by Allan Greer and Jodi Bilinkoff, 51–75. New York: Routledge, 2003.
  • Mumford, Jeremy Ravi. Vertical Empire: The General Resettlement of Indians in the Colonial Andes. Durham, NC: Duke University Press, 2012.
  • Numhauser, Paulina. Mujeres indias y señores de la coca: Potosí y Cusco en el siglo XVI. Madrid: Cátedra, 2005.
  • Robins, Nicholas A. Mercury, Mining, and Empire: The Human and Ecological Cost of Colonial Silver Mining in the Andes. Bloomington: Indiana University Press, 2011.
  • Rudolph, William E. “The Lakes of Potosí.” Geographical Review 26 (1936): 529–554.
  • Saignes, Thierry. “Notes on the Regional Contribution to the Mita in Potosí in the Early Seventeenth Century.” Bulletin of Latin American Research 4.1 (1985): 65–76.
  • Saignes, Thierry. “Capoche, Potosí y la coca. El consumo popular de estimulantes en el siglo XVII.” Revista de Indias 48.182–183 (1988): 207–235.
  • Salazar-Soler, Carmen. “Los ‘expertos’ de la Corona. Poder colonial y saber local en el Alto Perú en los siglos XVI y XVII.” De Re Metallica 13.2 (July–December 2009): 83–94.
  • Sordo, Emma M. “Civilizational Designs: The Architecture of Colonialism in the Native Parishes of Potosí.” PhD diss., University of Miami, 2000.
  • Tandeter, Enrique. Coercion and Market: Silver Mining in Colonial Potosí, 1692–1826. Translated by Richard Warren. Albuquerque: University of New Mexico Press, 1993. First Spanish edition, 1992.
  • TePaske, John J. A New World of Gold and Silver. Edited by Kendall W. Brown. Leiden, The Netherlands, and Boston: Brill, 2010.
  • Van Buren, Mary, and B. Mills. “Huayrachinas and Tocochimbos: Traditional Smelting Technology of the Southern Andes.” Latin American Antiquity 16.1 (2005): 2–25.
  • Wiedner, David. “Forced Labor in Colonial Peru.” The Americas 16 (1960): 357–383.
  • Zavala, Silvio. El servicio personal de los indios en el Perú. 3 vols. Mexico City: El Colegio de México, 1978–1980.