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date: 26 September 2017

Mercury and Silver Mining in the Colonial Atlantic

Summary and Keywords

From the time that Columbus arrived in the Caribbean until Spain surrendered power over its mainland American colonies in the early 19th century, Spanish and Portuguese colonial mines poured forth vast amounts of bullion, including some gold and a far greater quantity of silver, both in terms of weight and its overall value relative to gold. Fiscal records indicate that Spanish Americans officially refined gold worth approximately 374,000,000 pesos, each consisting of 272 maravedís, whereas the amount of silver produced reached a value of 3,432,000,000 pesos (to these figures need to be added contraband output, estimated to have been around 17–20 percent). In other words, the colonies refined nine times more silver than gold. While Columbus, Cortés, and other earlier explorers may have fantasized primarily about gold, it was the flood of American silver that touched off the price revolution in Europe and monetarized the emerging world economy, especially because China had a voracious appetite for silver, not gold. At the same time in the American colonies, mining distorted economic life because of the incentives the industry received from a silver-hungry monarchy. Mining also had profound consequences for indigenous society, severely exploited to provide workers for the mines and refining mills.

Colonial refiners used two methods to beneficiate their silver ores, smelting and amalgamation. Smelting was suitable for all types of American silver ores but required large amounts of fuel to heat the ovens. It remained widely used throughout Mexico during the entire colonial period. Amalgamation was a newer technology, adapted to American ores during the mid-16th century. Although it did not require large quantities of charcoal and other fuels, as smelting did, amalgamation depended on the availability of mercury. Nearly all quicksilver used in colonial Spanish American silver mining came from either Huancavelica (Peru) or Almadén (Spain), with occasional supplements from Idria (Slovenia). Whereas both smelting and amalgamation were used widely in Mexico, Andean mines relied on amalgamation.

Keywords: mining, silver, mercury, amalgamation, smelting, mita, Potosí, Huancavelica, Zacatecas, Guanajuato, Almadén

Based on research conducted during his visit to Spanish America at the beginning of the 19th century, the great German naturalist Alexander von Humboldt compiled an estimate of how much gold and silver the colonial Latin American mines produced. He analyzed the colonial mining industry, examined royal treasury registers, and consulted the economic writings of European experts. Humboldt then calculated that in a little over three centuries, the Spanish and Portuguese colonies had generated the equivalent of 5,706 million pesos (each worth 272 maravedís, the famous peso of eight reales or piece of eight) of gold and silver. Of that amount 4,720 million pesos were produced legally and officially registered by the colonial treasuries, while another 987 million, he estimated, were contraband output and escaped registration. Peru and Charcas (the latter roughly equivalent to modern-day Bolivia) officially refined the equivalent of 1,935 million, with an additional 474 million in illicit output, for a total of 2,429 million. This was almost entirely silver, with a small amount of gold, and it constituted 42 percent of overall production in Latin America. Next came New Spain, with the Mexican mines yielding 36 percent of the overall total, 1,970 million pesos’ worth of gold and silver. Brazil followed, with 15 percent, equivalent to 856 million pesos, all of which was gold production, and then New Granada, where the mines of Colombia produced 5 percent of the total, almost all of which was gold, the equivalent of 255 million silver pesos. Chile made up the remaining 2 percent, or 138 million pesos of gold and silver. Humboldt guessed that contraband production represented 17.3 percent of the totals, with illicit output being particularly high in the early years of Potosí, after the great mines there were discovered in 1545 in the southern highlands of Charcas, and in the gold fields of Brazil.1 By 1600 Spaniards had found the major silver districts in the central Andes and a 600-mile stretch in Mexico, moving northwest from Pachuca to Santa Bárbara. The only significant American source of mercury discovered during colonial times was at Huancavelica in central Peru.

The American colonies were famous throughout the Atlantic world for of gold, due in part to the plunder that Hernán Cortés and Francisco Pizarro sent back to Spain from their conquests of Mexico and Peru and because of the legends of El Dorado and the Seven Cities of Cíbola. It was silver, nevertheless, that predominated as the chief source of American mineral wealth. Once the first colonial mines were exploited in Mexico and Peru in the 1530s and 1540s, silver reigned supreme. Its production rose in the mid-1500s and continued to expand until the early 1600s, a result of the flood of silver flowing forth from Potosí. From 1580 to 1610, Potosí miners refined more than six million pesos of silver per year. No other silver mines compared to it. When output from Potosí’s Cerro Rico (Rich Hill) stagnated and then gradually declined after 1620, overall mining production for Spanish America also dropped. The great 16th-century boom at Potosí had ushered in the first Age of Silver in the Americas. Meanwhile, gold output remained relatively low and stable until the 1690s, when frontiersmen exploring westward from São Paulo discovered the gold fields of Minas Gerais in Brazil. For the next century they turned Brazil into a major mining economy, and in fact, from 1720 to 1750, gold represented around 40 percent of the value of Latin American mining output.

At Potosí, mining, as reflected by the amount of silver registered by the royal treasury, can be broken down into four periods. The first lasted from the discovery of silver at Potosí in 1545 until 1570, when rich, oxidized surface ores were refined by indigenous workers primarily using indigenous technology, specifically the guayra, a small smelting oven. By 1570, however, production at Potosí had plateaued at around 500,000 kilograms per decade, the surface ores were depleted, and the mines faced an impending crisis. It was at that point that technological change transformed operations, with the introduction of amalgamation as a method for refining ore. The new refining technology helped usher in the great boom at Potosí. Using amalgamation, output more than tripled to 1.7 million kilograms per decade from 1591 to 1610. The third period at Potosí began around 1640 and lasted until 1730. This was an era of declining production, when output fell from 1.3 million kilograms per decade to 325,000 kilograms. Thereafter, beginning in the 1730s a modest increase occurred, reaching almost 800,000 kilograms in the 1790s.2 One factor in the revival was the crown’s reduction of the tax on silver production at Potosí. From the beginning, silver refiners had paid the royal quinto of 20 percent. In an attempt to stimulate mining output, however, the crown reduced the tax in 1735 to 10 percent, the royal diezmo.3 It is worth noting, by the way, that many Mexican refiners had paid the diezmo rather than the quinto for a century prior to its reduction at Potosí. In some ways, Potosí’s great richness and apparent continued prosperity led royal officials to assume that Peruvian refiners could pay double the tax, whereas Mexican refiners needed relief from the quinto.

The second Age of Silver, during the 18th century, was Mexican in its origins. Compared to Potosí, Mexican silver output languished during the early colonial period but then began a gradual increase in the 1660s. Mexico became a silver powerhouse in the 18th century. It was refining 200 million pesos of silver per decade by the end of the colonial period, four or five times more than it produced in the early 1600s. In part this was because of strong production in old mining districts such as Zacatecas and particularly Guanajuato, the latter being the greatest silver producer of the 18th century. But it was also because of the discovery and exploitation of new silver deposits in the northern part of the viceroyalty, such as Sombrerete, Parral, Bolaños, and Santa Bárbara.4 Mexico also benefitted from strong investment in the mining industry by merchants, and their infusions of commercial capital helped modernize the mines through such techniques as driving central shafts to provide easier, more efficient access to the pits, both for extracting ore and for draining water from the deepest pits.5 Mexico had no mining district that equaled the importance of Potosí, but it did have a number of major reales de minas (mining districts). The most important in terms of overall output was Zacatecas, which over the colonial period produced 10.1 million kilograms of fine silver, or 23 percent of the Mexican total. Next came Guanajuato, which generated 19 percent of Mexican silver, nearly 8.5 million kilograms. But Guadalajara, México, Durango, San Luis Potosí, and Pachuca were important in their own rights, each registering at least two million kilograms. Thus, Mexico had seven fiscal districts that registered at least two million kilograms silver.

In the Andes a different situation existed. Potosí recorded 62 percent of Andean silver, the equivalent of 22.2 million kilograms. This was significantly more than the combined production of both Zacatecas and Guanajuato, the two richest Mexican districts. Unlike Mexico, however, the Andes lacked a multitude of other rich districts. Besides Potosí, only Oruro, with 4.2 million kilograms and 12 percent of overall production, generated at least two million kilograms of fine silver over the colonial period.6 This explains both the justifiable fame of Potosí, which had no rival in terms of output, and the fact that after Potosí’s decline around 1630, it was Mexico that became the great silver giant during the remainder of the colonial period.

To put Potosí in perspective, the greatest Mexican silver producer, Zacatecas, reached 500,000 kilograms per decade only six times and never surpassed 700,000 kilograms. It was Guanajuato that in the late colonial period began to approach the output of Potosí during its heyday: from 1770 to 1810, Guanajuato consistently produced a million kilograms per decade, reaching more than 1.2 million in the 1790s. Even so, this was less than 75 percent of Potosí’s peak. In other words, the richness of Potosí was incomparable; to be worth a Potosí was to have extraordinary value.

Silver Refining

Although there are many types of silver ore, Spanish American refiners had the good fortune of having to process only two basic types: (1) silver sulfide compounds (called negrillos), which were sometimes transformed by long-term weathering in surface layers to become silver chlorides (called pacos or colorados), together with elemental silver; and (2) argentiferous galena, or lead sulfide that contained silver compounds. Andean silver deposits were generally of the silver sulfide variety while silver ores in New Spain might be either silver sulfides or argentiferous galena.7

Smelting

Colonial refiners used two methods to beneficiate their silver ores, smelting and amalgamation. Silver sulfide ores could be processed by either smelting or amalgamation, whereas amalgamation could not beneficiate argentiferous galena, which had to be refined by smelting. Although smelting was suitable for all types of American silver ores, it required large amounts of fuel to heat the ovens. Refiners using smelting needed considerable skill because they had to determine the correct reagents to mix with the ground ore, generally greta, or litharge (lead oxide), which triggered the chemical reactions to separate the silver from the other materials when the ore was heated in the smelting ovens. Mexican refiners employed smelting throughout the entire colonial period.8 Whereas smelting required great quantities of charcoal or other fuels, it did not need huge capital investments as was true with amalgamation, for which refiners had to build large ingenios (mills and refining plants) and other infrastructure to crush and process the ores.9

The presence in Mexico of lead sulphide ores, which colonial refiners could only process by smelting, is reflected in the royal tax records. Depending upon the Mexican region and thus the type of silver ore being processed, the treasury accounts often contain two tax registers: plata de azogue, silver refined by amalgamation; and plata de fuego, silver processed by smelting. Mexican refiners produced approximately a third of the viceroyalty’s silver by smelting, and smelting was responsible for over half the silver registered at Durango, Sombrerete, Zimapán, and Chihuahua.10 Accounts from Andean mining districts make no such distinction, the assumption being that all, or nearly all, the silver had been refined by amalgamation, even though smelting would have worked well in Peru and Charcas also. Despite the large Andean camps’ reliance on amalgamation, some small-scale refiners probably continued to use smelting. The indigenous trapicheros (owners of rustic human-powered grinding mills) at Potosí, for example, may have employed some form of guayra to refine their high-grade ores, although they also used amalgamation.11

Amalgamation

Amalgamation was a newer technology than smelting, adapted to American ores during the mid-16th century. Although Venetians had probably amalgamated silver ores as early as 1480, and the process had clearly been used for gold even earlier, it remained for Bartolomé de Medina to adapt it for use in Mexico in 1555. It entailed mixing mercury and salt with crushed ore, plus a magistral, or reagent (usually copper or iron pyrite). The salt began a chemical reaction in which the reagent released the silver from the ore to form an amalgam with the mercury. Through a flotation process, workers then washed away everything but the amalgam, which they heated to separate the silver from the mercury. They attempted to capture the mercury to reuse it.12 Spanish officials concluded that one pound of mercury was lost to produce one mark of silver. They used this ratio, called the correspondencia, to determine whether refiners were paying sufficient tax on their silver, given the quantity of mercury they had purchased, or whether they were trying to hide silver production to avoid paying taxes. In Mexico amalgamation became known as the patio process because the crushed ore, mercury, and reagent were mixed on large circular patios. Amalgamation did not require large quantities of charcoal and other fuels, as smelting did, but it depended on the availability of mercury, which was an expensive industrial input. Azogueros (amalgamators) might pay one hundred pesos for a hundred pounds of mercury, with which they could refine one hundred marks of silver (800 pesos). Thus, mercury represented as much one-eighth of the cost of silver production. Nearly all mercury used in colonial Spanish American silver mining came from either Huancavelica (Peru) or Almadén (Spain), with occasional supplements from Idria (Slovenia).

Amalgamation clearly predominated at Potosí, where it replaced smelting in the 1570s. Potosí’s ore consisted of silver sulfides (negrillos), but weathering had converted those above the water table on the surface of the Cerro Rico into colorados (silver chlorides). With their guayras indigenous refiners could easily smelt the rich colorados found during the first two decades after Potosí’s discovery in 1545. During the initial boom at Potosí, there were reportedly 6,000 guayras burning on the ridges above the city and shining like fireflies in the night.13 But smelting of negrillos required different techniques that early refiners did not understand, and thus by 1570 when workers began to extract more and more silver sulfides the guayra technique mistakenly seemed inappropriate. It was at this point, in 1571–1572, that Pedro Hernández de Velasco and others managed to introduce at Potosí a form of amalgamation developed in Mexico.14

At Potosí, refiners did the mixing in boxes called buitrones rather than Mexican-style patios. The process began with workers pulverizing the ore in water-driven stamp mills. The water wheel raised large hammers, which fell on the ore to crush it. Workers then put the ore in the buitron and mixed it with salt, water, and the appropriate magistral. Periodically the mixture was stirred until the chemical reaction had amalgamated the silver with the mercury.

Once the inventive refiners at Potosí had adapted amalgamation to local conditions and determined the proper reagents, they needed to build the ingenios. It was at this point that Viceroy Francisco de Toledo (who governed from 1569–1581) entered the stage, eager to increase silver output and willing to work with the mine owners and silver refiners to ensure that the flow of silver from Potosí was not interrupted. Toledo concluded that this required two types of government intervention. To begin with, he pledged to supply Potosí with plentiful, secure supplies of mercury. The viceroy also committed the government to subsidize construction of the refining plants. To offset the capital cost, he agreed to provide the miners and azogueros with drafts of cheap, forced indigenous labor (the mita), which they could use to extract ore or to beneficiate it. The azogueros soon built the ingenios. They found that the water-driven mills functioned well during the rainy season, from December to February, but lack of flow in the river at other times hindered operations. As a result, the azogueros constructed reservoirs in the surrounding highlands to capture run-off and enable to mills to grind ore year-round.15 At one point Potosí had forty ingenios in operation.

Mercury Mining

Toledo felt confident in making this commitment because Spaniards had discovered rich deposits of cinnabar (mercuric sulfide) a decade earlier at Huancavelica in the mountains southeast of Lima.16 The viceroy expropriated the mercury mines at Huancavelica from the individuals who had initially staked claims to them. He subsequently operated them through a government contract with a guild of mineros (mine operators), who agreed to provide a specified amount of mercury each year at a fixed price. The viceroy also rewarded them with a mita of forced indigenous labor. The government assumed responsibility for making sure the mercury was transported from Huancavelica to Potosí and the other viceregal silver mines and coordinated its sale to the silver refiners.17

As the chief supplier of mercury for the Andean silver mines, Huancavelica was essential to the mining economy. One viceroy, in fact, called Potosí and Huancavelica the two poles that supported the kingdom.18 Yet work at Huancavelica was even more dangerous than at the silver mines. Mercury was poisonous, and during the early decades of work there, the guild failed to ventilate the mine. Critics called mita service there a death sentence. Others reported that indigenous mothers intentionally broke their sons’ arms to incapacitate them for work in the mercury mines. Conditions became so deadly that in 1600, Viceroy Luis de Velasco closed Huancavelica’s great Santa Bárbara mine. Underground work remained prohibited until 1604, when his successor, desperate to provide Potosí with mercury, reopened the mine. Ventilation finally improved in 1643, when the 600-meter-long Our Lady of Bethlehem adit was finished after forty years. Its completion was due, in part, to the first recorded use of blasting in mining. Development of new refining ovens to capture more of the mercury distilled from the cinnabar also showed the technological innovation occurring in the Andean mining industry. Given Potosí’s predominance, it is not surprising that it consumed the majority of Huancavelica’s quicksilver. Around 1600, for example, Potosí received 5,000 quintales of mercury per year, with another 1,000 distributed to other Peruvian mining districts. By the 1730s, however, only 31 percent of Huancavelica’s mercury went to Potosí, with Oruro receiving 21 percent and Pasco, Cailloma, Chucuito, and Lucanas consuming 8 or 9 percent each.

For most of the colonial period, Mexican silver refiners received their mercury from Almadén in Spain and occasionally Idria in Slovenia, whereas Huancavelica in Peru supplied mines throughout the Andes. Almadén had been worked since at least Roman times. In the 16th and 17th centuries, it was exhausted and had difficulty supplying Mexican demand. Between 1694 and 1698, for example, Almadén produced little more than 1,000 quintales of quicksilver per year. Then, in the late 1690s, rich new cinnabar deposits were discovered, and from 1699 to 1704 Almadén averaged more than 7,000 quintales annually.19 From that point on, Almadén shipped great quantities of mercury to Mexico, contributing to the upsurge in New Spain’s silver production.20 After 1750 Almadén also supplemented what Huancavelica provided to Peru.

Several factors account for Andean reliance on amalgamation, unlike Mexico, where smelting continued to have a major role in refining. Peruvian refiners at Potosí were intelligent and acted in their own economic self-interest. They had sound reasons for choosing to refine with mercury. First, they had a ready source of mercury at Huancavelica. Whereas Mexico depended on precarious shipments from Almadén, or even from Huancavelica, Andean refiners could rely on sufficient, if not plentiful, supplies from Huancavelica. Second, most Andean mines lay at a much higher altitude than those in Mexico. Guanajuato, Durango, and San Luis Potosí lay at 2,000 meters or lower, and Zacatecas and Pachuca reached only 2,400 meters. Peruvian mines, on the other hand, were usually located high in the Andes: Potosí, 4,090 meters; Oruro and Huancavelica, around 3,700 meters; and Cerro de Pasco, 4,380 meters. Although this difference had implications for the challenge to human labor at such heights in the Andes, it also affected the availability of fuel for smelting ovens. Mexican smelters used huge quantities of charcoal but could make the charcoal from wood found in nearby forests. In the Andes, areas surrounding mines such as Potosí and Huancavelica were quickly denuded of trees. The guild at Huancavelica had to fuel the mercury ovens with icho grass. To heat the amalgam to separate the mercury and silver, azogueros at Potosí used yareta (a large moss-like cushion with long roots that could be burned for fuel), icho, and llama dung. Not only did amalgamation suit the type of ores found in the Andes, but it did not require great quantities of fuel, which were not easily available. Third, it was easier to control contraband production when refiners used amalgamation. Using the correspondencia, officials expected that amalgamation produced at least one mark of silver for each pound of mercury expended. This gave the colonial state a reason to prefer and promote amalgamation. Fourth, mercury was a royal monopoly and the crown had an interest in selling it. The king claimed for himself a royal quinto, 20 percent of the mercury refined at Huancavelica. The crown generally sold Huancavelica mercury to the azogueros for what it had paid the Huancavelica guild plus the costs of transporting it to the silver mines. But it also sold the royal share, the quinto, at net profit, giving the crown a handsome benefit, perhaps as much as 100,000 pesos if the gremio produced 6,000 quintales valued at eighty-five pesos each. It has been argued that the crown’s commercial interest was the chief driving factor behind the predominance of amalgamation in the Andes.21 But it is doubtful that refiners at Potosí would have committed to amalgamation if it had been less efficient and profitable than smelting. Furthermore, in the 18th century, with more abundant mercury available from Almadén at a much lower cost, the crown lowered its price to the amalgamators. This played a role in the upsurge in silver production during the second half of the century.22

Labor

Throughout Spanish America, colonial mining used both free and forced labor, although what appeared on the surface to be free wage labor often hid a considerable amount of coercion. For the Andean region, mention of colonial mining and Potosí in particular immediately evokes images of the mita. Loosely based on the indigenous mit’a and formally established by Viceroy Francisco de Toledo, the colonial mita forced indigenous tributaries from sixteen surrounding highland provinces to rotate as workers in the mines and refining mills of Potosí for a year. In the beginning, the mita drew as many as 13,000 workers each year from those provinces, which stretched from Cana y Canches, Lampa, and Azangaro near Cuzco to Chichas and Pilaya y Paspaya south of Potosí.23 A third of the draft was to work as mitayos each week, for which the worker received a small wage, about a third of what a free worker (mingado) earned. Toledo established the mita in order to subsidize the construction of refining mills by the azogueros and also to mobilize workers to participate in the colonial economy.

Miners elsewhere in the Andes sometimes managed to secure mitas. A small contingent of mitayos toiled at Cailloma, for example, but azogueros at Oruro, the second most productive Andean silver district, never managed to secure a permanent mita, in part because they had to compete geographically for workers from the same provinces that supplied Potosí.24 The second most important mita, perhaps more infamous than that at Potosí, was the draft that Toledo assigned to the mercury mines at Huancavelica. In the early years it compelled as many as 3,000 tributaries to work in the poisonous mines southeast of Lima, drafting mitayos from Jauja in the north to Cotabambas near Cuzco.25

Both mitas soon declined, nevertheless, and proved unable to provide the large number of workers that Toledo envisioned. By the mid-1600s the Huancavelica mita was officially 620 and often provided fewer workers than that, whereas the Potosí draft fell to 4,000 or less. In part this was because of a decline in the overall indigenous population, due chiefly to the spread of Old World diseases. Toledo’s mita theoretically drafted one-seventh of tributaries each year, and with a smaller population the mita inevitably compelled fewer mitayos to trudge off more frequently to Potosí or Huancavelica, perhaps every second or third year. Second, curacas (indigenous lords), corregidores (provincial governors), priests, hacendados (Spaniards who owned agricultural and ranching estates), and other economic interests in the local provinces had an interest in keeping the tributaries at home, to exploit their labor, rather than allowing them to go off to the mines. This led to underreporting of tributary populations and the hiding of potential mitayos from the mining drafts. Third, the mitas provoked significant migration, with tributaries either remaining at the mines to work, particularly Potosí, or moving to provinces not subject to the mita to escape serving in it.26 The Huancavelica and Potosí mitas disrupted life in the indigenous villages and impeded their peoples’ ability to reproduce demographically and sustain their culture.

Yet free wage labor also existed in Andean mines, including Potosí and Huancavelica. Despite the dangerous conditions at Huancavelica, which led a Spanish observer to call the mines there a public slaughterhouse (“matadero público”),27 mercury producers managed to hire alquilas (free wage earners), paying them as much as a peso per day.28 This compared to 2–3 reales per day for mitayos (if, in fact, the mitayos received the pay to which they were legally entitled, there being frequent complaints that mitayos in the Andes were defrauded out of their wages). At Potosí, mingas (free laborers) earned 2–3 times more than the mitayos. Many workers there, both mitayos and mingas, also supplemented their pay by plundering the mines on the weekends as kajchas (ore robbers) for minerals which they sold to trapicheros, who ran small smelting operations. The kajcheo was, in effect, a form of ore-sharing. The mineros/azogueros hated it and tried unsuccessfully to eliminate both the kajchas and the trapicheros.29

All these workers, the kajchas, mingas, and alquilas, were at least superficially free wage laborers. Nonetheless coercion often drove them to the mines also, if not as overtly as in the case of the mitayos. They had to earn money to pay tribute to the encomenderos (Spaniard who had the right to collect tribute from a group of Indians and in turn was supposed to protect and Christianize them) and the monarch; they needed coins to pay the commercial repartos, goods forcibly distributed among indigenous inhabitants by the local governor, usually at exorbitant prices.30 Fiscal pressures from the colonial system forced nominally free men into the mines and refining mills. Many worked in the industry on a seasonal basis, going to the mines to earn money for tribute and repartos during slack periods in the agricultural calendar. They did not necessarily become permanent mine workers.

There was no mita in New Spain, although Spaniards did impose a repartimiento of tribute labor in some of the early mines near the heavily populated central highlands. The repartimiento was similar to the mita, although it never became as institutionalized nor was it extensively used.31 Furthermore, many of the most important Mexican silver mines lay in sparsely populated northern regions of the viceroyalty, making it difficult to rely on rotating drafts of forced labor. Free wage labor thus came to characterize Mexican silver mines much more than was true in Potosí. Ore-sharing, the pepena or partido, played a major role throughout the viceroyalty’s mines, with workers earning a daily wage plus a quantity of the ore they had extracted.32 The pepena stirred controversy and tension between workers and mineros. In times of bonanza, the mine owners tried to eliminate the pepena because they were reluctant to share the rich ores with their workers. But when ores were of poor quality and profits low, the owners tried to eliminate wages and force workers to receive their pay in nothing but the pepena of low-grade ore. Dispute over the pepena was one cause of the violent strike of 1766 at Real del Monte.33 More so than in the Andes, Mexican mine labor probably became more proletarianized. Mine operators had to recruit workers to the isolated mining districts and sometimes resorted to the enganche (coercive labor recruitment) to ensnare peasants. These workers were then held at the mines through debt peonage, a practice much less common at Andean mines.34

Consequences

It has been estimated that in 1500 Europe’s monetary stock amounted to approximately 3,500 metric tons of gold (3.5 million kilograms) and 37,500 metric tons of silver (37.5 million kilograms).35 American mining added 1.685 million kilograms of gold (an addition of 48 percent) and eighty-six million kilograms of silver (an increase of 229 percent). Discovery of American gold and silver seemed a fortuitous or even divine intervention to the Spaniards, but they also found the New World treasury troubling. Before American gold and silver began flooding into Iberia, Spaniards looked at gold as something pure, something that had intrinsic value independent of anything else. But the stream of precious metals upset the Spanish economy, causing widespread inflation. Soon it cost more gold or silver to purchase goods, undermining the traditional belief in precious metal’s intrinsic value. As the decades passed, Spaniards blamed the flood of American precious metals for the loss of their austere masculinity and for the appetite for feminizing luxury.36

In the colonies also, the focus on precious metals had unforeseen consequences. The colonial system emphasized mining and silver refining at the expense of other sectors of the economy. Indigenous populations and cultures were sacrificed on a silver altar. Mining wages were high, particularly compared to what laborers earned in Europe, but silver was not worth as much in Mexico or Peru as it was in Europe and as a result had less purchasing power. What money mine laborers earned, whether free or mitayo, was usually taken away by tribute, repartos, debt peonage, fraud, and the high cost of living in the mining cities. A few, like Antonio López de Quiroga in Potosí or the Conde de Regla of Pachuca, made vast fortunes,37 but many others discovered that mining profits were fleeting or never found a bonanza in the first place. Even the mine operators often found themselves impoverished. Merchants supplying the mines with goods and credit probably fared better. And mining polluted the environment. Today Huancavelica remains highly contaminated with mercury from its colonial ovens.38 Mexican smelters covered the surrounding towns and countryside with lead.39

Furthermore, American silver did not remain in the colonies or in Europe: most of it found its way to China, where demand for the white metal was insatiable. Indeed, silver had a much higher value in China relative to gold than it did in Europe or Spanish America. European traders could make a significant profit simply by taking silver to China and exchanging it for gold to be used for purchases in Europe. Whereas an ounce of gold was worth 12.5 ounces of silver in Europe in the early 1600s, the ratio was only 5.5 to 7.0 ounces of silver per ounce of gold in China.40 American silver made it possible for European and Spanish American elites to dress in Chinese silks. And Asian spices, silks, and porcelain made it possible for the Chinese to acquire the silver needed for their monetary system. In important ways, American silver made possible the global commerce that emerged in the 16th century.41

Discussion of the Literature

The mining of silver and mercury in colonial Spanish America continues to attract historians’ interest and research, in part because of the vital economic role played by the industry in the Spanish empire and due to the social and even cultural consequences of mining. The result has been important works dealing with overall mining production and the flow of bullion to both Europe and China; the positive and negative economic effects of mining for the colonies; the social impact of mining on workers and indigenous culture; the environmental legacy of mining; and the consequences for mining caused by the imperial reforms carried out by the new Bourbon dynasty during the 18th century.

The question of how much silver and gold were mined in colonial Latin America has held the attention of political economists and historians ever since the precious metals began to flood into Europe. Humboldt’s own calculations of the volume of mining production followed in the wake of estimates from Adam Smith, Jacques Necker, William Robertson, and others.42 In the 1930s Earl J. Hamilton published studies on the relationship between the arrival of American bullion in Spain and peninsular inflation, the “Price Revolution.” Hamilton’s work stimulated other studies evaluating his assertion that American gold and silver undermined Spanish economic development and that the bullion influenced economic conditions elsewhere in Europe.43 By studying early modern Dutch gazettes, Michel Morineau assessed the amount of American silver that escaped Spanish shipping and fiscal records.44 Although the amount of contraband mining output is impossible to measure, John TePaske has provided, based on fiscal records, a precise record of the quantity of gold and silver legally refined, by region and over time.45

Spanish American silver did more than monetarize the Americas and the Atlantic economy, although it certainly had that effect. The peso de ocho became the first global money of account. The U.S. dollar was, for example, the Americanized Spanish piece of eight. American silver also flowed, via the Atlantic or the Pacific, to China, where it paid for silk, spices, and other luxury goods desired by Europeans and Hispanic colonists. Studies by Dennis Flynn, Arturo Giráldez, and others indicate that most American silver ended up in China, where it monetarized the Asian economy.46

Although mining undoubtedly produced great wealth, scholars have debated the positive and negative impact of the industry for the colonies and for the Spanish empire. For some it was the sector of the economy that created commercial demand for American and overseas goods. It provided revenues for imperial defense and for Spain’s European ventures, whether the pursuit of Habsburg and Bourbon dynastic ambitions or the protection of Catholic interests. In addition, Spanish obsession with gold and silver, argue some historians, distorted the colonial economy and harmed other sectors, such as agriculture. Investment and labor subsidies went to mining at the expense of the rest of the economy.47

There is less debate about the social and cultural consequences of colonial mining. Pre-Hispanic indigenous societies had engaged in mining, particularly in the Andes. But it had not caused the massive migration, social dislocation, and exploitation which colonial mining inflicted. The colonial mita and Mexican enganche forced workers out of their villages, disrupted families, and profited Spaniards rather than the mine workers themselves, who often found themselves impoverished.

The Bourbon ascension to the Spanish throne in 1700 eventually led to attempts to modernize the colonial economy, primarily to provide greater revenues for the monarchy. The so-called Bourbon reforms had ramifications for the mining industry, as royal ministers were anxious to expand silver output.48 This led them to try to curb corruption and technological backwardness at Huancavelica and the silver mines. Missions of European mining and metallurgical experts visited the colonies, with mixed success.49

One of the most significant areas of focus for recent studies of colonial mining has been the industry’s environmental impact. Colonial smelters polluted mining districts with accumulations of poisonous lead. Even today Huancavelica suffers extraordinary levels of mercury contamination.50 The mercury mines there claimed the lives of many colonial workers,51 and while the silver mines and refineries were probably not as poisonous as Huancavelica, workers suffered premature death from silicosis, and cave-ins claimed many victims. Furthermore, the areas surrounding the mines were deformed by destruction of forests and the accumulation of tailings. Rivers ran with mining sludge.

Primary Sources

Numerous primary sources are available to researchers interested in colonial mining. The vast manuscript holdings of the Archivo General de Indias (AGI) in Seville contain thousands of documents related to Spanish American silver and mercury mining. There are useful published guides to the mining documents in some of the sections of the AGI.52 Parts of the AGI have been digitalized and are available online at Portal de Archivos Españoles. It is possible to search the holdings and identify documents related to mining that are available in digital format. In Spanish America, national archives and national libraries are also important repositories of colonial mining documents. This is particularly true of the Archivo General de la Nación in Lima and the Archivo General de la Nación in Mexico City, plus the Archivo Nacional in Sucre, Bolivia. In Madrid, the National Library and the Library of the Royal Palace have smaller but valuable collections of mining documents. Researchers should also consult the collections of provincial archives in Zacatecas, Guanajuato, and other mining districts. The archive located in the Casa de la Moneda in Potosí is invaluable.

Important primary sources related to mining have also been published, most of which are in Spanish but some of which have English translations. When Philip II ordered officials in the colonies to provide data about their provinces, their responses included useful information about mining and metallurgical activities.53 Some are available as the Relaciones geográficas, compiled for the territories of Spanish South America by Marcos Jiménez de la Espada in the 19th century.54 Before leaving office, viceroys of New Spain and Peru made reports to their successors of conditions within their jurisdictions, and because the mining industry was essential to both prosperity and royal revenues, they included details about silver and mercury production and any problems afflicting the industry in their reports. All of the viceroys’ relaciones have found their way into print.55 Late colonial studies of mining laws also offer context for understanding the industry.56 The same is true for early modern treatises on refining technologies and metallurgy used by colonial refiners.57

Sometimes provincial officials compiled reports similar to the viceroys’ relaciones. This was true, for example, in the case of Huancavelica in the 18th century. Jerónimo Sola y Fuente, governor of Huancavelica from 1736 to 1748, published a report of his administration,58 and Antonio de Ulloa, the great Spanish naturalist and naval officer who governed at Huancavelica from 1757 to 1764, composed a detailed description of the method of working the mercury mine, the refining techniques utilized by the guild that contracted with the government to produce mercury, the intricacies facing the superintendent of the mine (who was also the chief political and fiscal officer in the province), and other worthwhile information.59 Because of Potosí’s crucial status within the colonies, it received literary attention from both chroniclers and royal officials.60 Mexican mining also drew attention.61

Further Reading

Bakewell, Peter J.Silver Mining and Society in Colonial Mexico: Zacatecas, 1546–1700. Cambridge, U.K.: Cambridge University Press, 1971.Find this resource:

Bakewell, Peter J.Miners of the Red Mountain: Indian Labor in Potosí, 1545–1760. Albuquerque: University of New Mexico Press, 1984.Find this resource:

Bakewell, Peter J.Silver and Entrepreneurship in Seventeenth-Century Potosi: The Life and Times of Antonio Lopez de Quiroga. Albuquerque: University of New Mexico Press, 1988.Find this resource:

Bargalló, Modesto. La minería y la metalurgia en la América Española durante la época colonial. Mexico City: Fondo de Cultura Económica, 1955.Find this resource:

Brading, David A. “Mexican Silver Mining in the Eighteenth Century: The Revival of Zacatecas.” Hispanic American Historical Review 40.4 (1970): 665–681.Find this resource:

Brading, David A.Miners and Merchants in Bourbon Mexico, 1765–1810. Cambridge, U.K.: Cambridge University Press, 1971.Find this resource:

Brown, Kendall W. “The Spanish Imperial Mercury Trade and the American Mining Expansion under the Bourbon Monarchy.” In The Political Economy of Spanish American in the Age of Revolution, 1750–1850. Edited by Kenneth J. Andrien and Lyman L. Johnson, 137–168. Albuquerque: University of New Mexico Press, 1994.Find this resource:

Brown, Kendall W.A History of Mining in Latin America: From the Colonial Era to the Present. Albuquerque: University of New Mexico Press, 2012.Find this resource:

Coatsworth, John H. “The Mexican Mining Industry in the Eighteenth Century.” In The Economies of Mexico and Peru during the Late Colonial Period, 1760–1810. Edited by Nils Jacobsen and Hans-Jürgen Puhle, 26–45. Berlin: Colloquium Verlag, 1986.Find this resource:

Cole, Jeffrey A.The Potosí Mita, 1573–1700: Compulsory Indian Labor in the Andes. Stanford, CA: Stanford University Press, 1985.Find this resource:

Couturier, Edith Boorstein. The Silver King: The Remarkable Life of the Count of Regla in Colonial Mexico. Albuquerque: University of New Mexico Press, 2003.Find this resource:

Fisher, John R.Silver Mines and Miners in Colonial Peru, 1776–1824. Liverpool: Centre for Latin American Studies, University of Liverpool, 1977.Find this resource:

Graham, Richard L. “Long-Term Silver Mining Trends in Spanish America: A Comparative Analysis of Peru and Mexico.” American Historical Review 93.4 (October 1988): 898–935.Find this resource:

Guerrero, Saúl. “The History of Silver Refining in New Spain, 16c to 18c: Back to the Basics.” History and Technology 32.1 (2016): 2–32.Find this resource:

Heredia Herrera, Antonia. La renta del azogue en Nueva España: 1709–1751. Seville: Escuela de Estudios Hispano-Amerianos, 1978.Find this resource:

Humboldt, Alexander von. Political Essay on the Kingdom of New Spain. 4 vols. Translated by John Black. London: Longman, Hurst, Rees, Orme, and Brown, 1811–1822.Find this resource:

Ladd, Doris. The Making of a Strike: Mexican Silver Workers’ Struggles in Real del Monte, 1766–1775. Lincoln: University of Nebraska Press, 1988.Find this resource:

Lang, M. F.El monopolio estatal del mecurio en el México colonial (1550–1710). Mexico City: Fondo de Cultura Económica, 1977.Find this resource:

Lohmann Villena, Guillermo. Las minas de Huancavelica en los siglos XVI y XVII. Seville: Escuela de Estudios Hispano-Americanos, 1949.Find this resource:

Molina Martínez, Miguel. Antonio de Ulloa en Huancavelica. Granada: Universidad de Granada, 1995.Find this resource:

Robins, Nicholas A.Mercury, Mining, and Empire: The Human and Ecological Cost of Colonial Silver Mining in the Andes. Bloomington: Indiana University Press, 2011.Find this resource:

Tandeter, Enrique. Coercion and Market: Silver Mining in Colonial Potosí, 1692–1826. Translated by Richard Warren. Albuquerque: University of New Mexico Press, 1993.Find this resource:

TePaske, John J.A New World of Gold and Silver. Edited by Kendall W. Brown. Leiden, The Netherlands: Brill, 2010.Find this resource:

West, Robert C.The Mining Community in Northern New Spain: The Parral Mining District. Berkeley: University of California Press, 1949.Find this resource:

West, Robert C. “Early Silver Mining in New Spain, 1531–1555.” In In Quest of Mineral Wealth: Aboriginal and Colonial Mining and Metallurgy in Spanish America. Edited by Alan K. Craig and Robert C. West, 119–136. Geoscience and Man 33. Baton Rouge: Louisiana State University, 1994.Find this resource:

Whitaker, Arthur P.The Huancavelica Mercury Mines: A Contribution to the History of the Bourbon Renaissance in the Spanish Empire. Cambridge, MA: Harvard University Press, 1941.Find this resource:

Notes:

(1.) Alejandro de Humboldt, Ensayo politico sobre el reino de la Nueva España, 5 vols. (Mexico City: Editorial Pedro Robredo, 1941), 3:378–382.

(2.) John J. TePaske, A New World of Gold and Silver, ed. Kendall W. Brown (Leiden, The Netherlands: Brill, 2010), 150–153, 188–190.

(3.) Enrique Tandeter, Coercion and Market: Silver Mining in Colonial Potosí, 1692–1826 (Albuquerque: University of New Mexico Press, 1993), 11.

(4.) TePaske, New World, 82.

(5.) David A. Brading, Miners and Merchants in Bourbon Mexico, 1765–1810 (Cambridge, U.K.: Cambridge University Press, 1971), 149–153 and passim.

(6.) TePaske, New World, 148; and Richard L. Garner, “Long-Term Silver Mining Trends in Spanish America: A Comparative Analysis of Peru and Mexico,” American Historical Review 93.4 (October 1988): 907.

(7.) Saúl Guerrero, “The History of Silver Refining in New Spain, 16c to 18c: Back to the Basics,” History and Technology 32.1 (2016): 5–6.

(8.) Guerrero, “History of Silver Refining,” 8–10.

(9.) Peter Bakewell, Silver Mining and Society in Colonial Mexico: Zacatecas, 1546–1700 (Cambridge, U.K.: Cambridge University Press, 1971), 138.

(10.) Kendall W. Brown, “The Spanish Imperial Mercury Trade and the American Mining Expansion Under the Bourbon Monarchy,” in The Political Economy of Spanish America in the Age of Revolution, 1750–1850, eds. Kenneth J. Andrien and Lyman L. Johnson (Albuquerque: University of New Mexico Press, 1994), 149; and Guerrero, “History of Silver Refining,” 8.

(11.) Tandeter, Coercion and Market, 90–92.

(12.) Modesto Bargalló, La minería y la metalurgia en la América española durante la época colonial (Mexico City: Fondo de Cultura Económica, 1955), 112–130.

(13.) José de Acosta, Natural and Moral History of the Indies, ed. Jane E. Mangan, trans. Frances López-Morillas (Durham, NC: Duke University Press, 2002), 183.

(14.) Bargalló, Minería y la metalurgia, 134–138.

(15.) Acosta, Natural and Moral History, 192.

(16.) For a general overview of works related to Huancavelica, see Adrian J. Pearce, “Huancavelica 1563–1824: History and Historiography,” Colonial Latin American Review 22.3 (2013): 422–440.

(17.) Kendall W. Brown, “El sistema de los Habsburgo de distribución del mercurio europeo y americano en las minas de plata andinas,” in Minería e imperio en Hispanoamérica colonial: Producción, mercados y trabajo, ed. Kendall W. Brown (Lima: Banco Central de la Reserva del Perú e Instituto de Estudios Peruanos, 2015), 51–76.

(18.) “Relación del Príncipe de Esquilache,” in Los virreyes españoles en América durante el gobierno de la Casa de Austria: Peru, eds. Lewis Hanke and Celso Rodríguez, vol. 2, Biblioteca de Autores Españoles 281 (Madrid: Atlas, 1978), 159.

(19.) A. Matilla Tascón, Historia de las minas de Almadén, vol. II: Desde 1646 a 1799 (Madrid: Minas de Almadén y Arrayanes and Instituto de Estudios Fiscales, Ministerio de Economía y Hacienda, 1987), 53, 103–108; and Antonia Heredia Herrera, La renta del azogue en Nueva España: 1709–1751 (Seville: Escuela de Estudios Hispanoamericanos, 1978).

(20.) Brown, “Spanish Imperial Mercury Trade,” 141–146.

(21.) Guerrero, “History of Silver Refining,” 15, 22.

(22.) Brown, “Spanish Imperial Mercury Trade,” 144; and Garner, “Long-Term Silver Mining Trends,” 916–917, 922.

(23.) Jeffrey A. Cole, The Potosí Mita, 1573–1700: Compulsory Indian Labor in the Andes (Stanford, CA: Stanford University Press, 1985), 9–12.

(24.) Ann Zulawski, They Eat from Their Labor: Work and Social Change in Colonial Bolivia (Pittsburgh, PA: University of Pittsburgh Press, 1995), 93.

(25.) Guillermo Lohmann Villena, Las minas de Huancavelica en los siglos XI y XVII (Seville: Escuela de Estudios Hispano-Americanos, 1949), 91–100.

(26.) Ann M. Wightman, Indigenous Migration and Social Change: The Forasteros of Cuczo, 1520–1720 (Durham, NC: Duke University Press, 1990), 58–63, 70–73; and Zulawski, They Eat from Their Labor, 87.

(27.) Informe de Damián de Jeria, 20 January 1604, Archivo General de Indias, Lima 34.

(28.) Barbara Bradby, “The ‘Black Legend’ of Huancavelica: The Mita Debates and Opposition to Wage Labour in the Colonial Mercury Mine,” in Hombres, Técnica, Plata: Minería y sociedad en Europa y América, siglos XVI–XIX, eds. Julio Sánchez Gómez and Guillermo Mira Delli-Zotti (Seville: Aconcagua, 2000), 227–258.

(29.) Tandeter, Coercion and Market, 74–114.

(30.) Peter Bakewell, Miners of the Red Mountain: Indian Labor in Potosí, 1545–1650 (Albuquerque: University of New Mexico Press, 1984), 44.

(31.) Charles Gibson, The Aztecs Under Spanish Rule: A History of the Indians of the Valley of Mexico, 1519–1810 (Stanford, CA: Stanford University Press, 1964), 228–230.

(32.) Bakewell, Silver Mining and Society, 125; and Brading, Miners and Merchants, 147.

(33.) Doris M. Ladd, The Making of a Strike: Mexican Silver Workers’ Struggles in Real Del Monte, 1766–1775 (Lincoln: University of Nebraska Press, 1988), 44; and Edith Boorstein Couturier, The Silver King: The Remarkable Life of the Count of Regla in Colonial Mexico (Albuquerque: University of New Mexico Press, 2003), 67, 84–85.

(34.) Brading, Miners and Merchants, 147.

(35.) Geoffrey Parker, “The Emergence of Modern Finance in Europe, 1500–1730,” in The Fontana Economic History of Europe, ed. Carlo M. Cipolla, vol. 2 (London: Fontana, 1972–1976), 527.

(36.) This is a principal theme of Elvira Vilches, New World Gold: Cultural Anxiety and Monetary Disorder in Early Modern Spain (Chicago: University of Chicago Press, 2010).

(37.) Peter Bakewell, Silver and Entrepreneurship in Seventeenth-Century Potosí: The Life and Times of Antonio López de Quiroga (Albuquerque: University of New Mexico Press, 1988); and Couturier, Silver King.

(38.) Nicholas A. Robins, Mercury, Mining, and Empire: The Human and Ecological Cost of Colonial Silver Mining in the Andes (Bloomington: Indiana University Press, 2011), particularly 101–148.

(39.) Guerrero, “History of Silver Refining,” 2, 16–17.

(40.) Charles R. Boxer, “Plata es sangre: Sidelights on the Drain of Spanish-American Silver in the Far East, 1550–1700,” in European Entry into the Pacific: Spain and the Acapulco-Manila Galleons, eds. Dennis O. Flynn, Arturo Giraldez, and James Sobredo (Burlington, VT: Ashgate, 2001), 169.

(41.) William Lytle Schurz, The Manila Galleon (New York: Dutton, 1939); Pierre Chaunu, Les Philippines et le Pacifique des Ibériques (XVIe, XVIIe, XVIIIe siècles) (Paris: S.E.V.P.E.N., 1960); and William S. Atwell, “Another Look at Silver Imports into China, ca 1635–1644,” Journal of World History 16.4 (2005): 467–489.

(42.) Humboldt, Ensayo politico, 3:373–378.

(43.) Earl J. Hamilton, American Treasure and the Price Revolution in Spain, 1501–1650 (Cambridge, MA: Harvard University Press, 1934); and Hamilton, War and Prices in Spain, 1651–1800 (Cambridge, MA: Harvard University Press, 1947).

(44.) Michel Morineau, Incroyables gazettes et fabuleux métaux: les retours des trésors américains d’après les gazettes hollandaises (XVI.–XVIII. siècles) (London: Cambridge University Press, 1985).

(45.) TePaske, New World.

(46.) Dennis O. Flynn and Arturo Giráldez, “Born with a ‘Silver Spoon’: The Origin of World Trade in 1571,” Journal of World History, 6.2 (1995): 201–221; Flynn and Giráldez, “Cycles of Siler: Global Economic Unity through the Mid-Eighteenth Century,” Journal of World History 13.2 (2002): 391–427; and William S. Atwell, “International Bullion Flows and the Chinese Economy circa 1530–1650,” Past & Present 95 (1982): 68–90.

(47.) John R. Fisher, “Mining and the Peruvian Economy in the Late Colonial Period,” in The Economies of Mexico and Peru during the Late Colonial Period, 1760–1810, eds. Nils Jacobsen and Hans-Jürgen Puhle (Berlin: Colloquium Verlag, 1985), 46–63; and John H. Coatsworth, “The Mexican Mining Industry in the Eighteenth Century,” in Economies of Mexico and Peru, eds. Nils Jacobsen and Hans-Jürgen Puhle (Berlin: Colloquium Verlag, 1985), 26–45.

(48.) Walter Howe, The Mining Guild of New Spain and Its Tribunal General, 1770–1821 (Cambridge, MA: Harvard University Press, 1949); and Adrian J. Pearce, “Huancavelica 1700–1759: Administrative Reform of the Mercury Industry in Early Bourbon Peru,” Hispanic American Colonial Review 79.4 (1999): 669–702.

(49.) John Fisher, Minas y mineros en el Perú colonial, 1776–1824 (Lima: Instituto de Estudios Peruanos, 1977), 115–152; and Iago Gil Aguado, “La expedición minera del barón de Nordenflicht y las autoridades peruanas,” Anuario de Estudios Americanos 72.1 (2015): 263–288.

(50.) Nicholas A. Robins, Nicole Hagan, et al., “Estimations of historical atmospheric mercury concentrations from mercury refining and present-day soil concentrations of total mercury in Huancavelica, Peru,” Science of the Total Environment 426 (2012): 146–154.

(51.) Kendall W. Brown, “Workers’ Health and Colonial Mercury Mining at Huancavelica, Peru,” The Americas 57.4 (2001): 467–496.

(52.) Documentos existentes en el Archivo General de Indias, sección de Lima, in La minería hispana e hispanoamericana, 2 tomes, ed. J. Muñoz Perez, vol. 8 (León, Spain: Cátedra de San Isidoro, 1970–1974).

(53.) Juan López de Velasco, Geografía y descripción universal de las Indias, recopilada desde el año de 1571 al de 1574 (Madrid: Establecimiento Tipográfico de Fortanet, 1894).

(54.) Marcos Jiménez de la Espada, ed., Relaciones geográficas de Indias—Perú, 3 vols. Biblioteca de Autores Españoles 183–185 (Madrid: Atlas, 1965).

(55.) Los virreyes españoles en América durante el gobierno de la Casa de Austria: Perú, eds. Lewis Hanke and Celso Rodriguez, 7 vols., Biblioteca de Autores Españoles 280–286 (Madrid: Atlas, 1978–1980); and Los virreyes españoles en América durante el gobierno de la Casa de Austria: México, eds. Lewis Hanke and Celso Rodriguez, 5 vols., Biblioteca de Autores Españoles 273–277 (Madrid: Atlas, 1976–1978).

(56.) Francisco Xavier de Gamboa, Commentaries on the Mining Ordinances of Spain: Dedicated to his Catholic Majesty Charles III, trans. Richard Heathfield, 2 vols. (London: Longman, Rees, Orme, Brown & Green, 1830).

(57.) Georgius Agricola, De Re Metallica, in The Mining Magazine, eds. and trans. Herbert Clark Hoover and Lou Henry Hoover (London: Salisbury House, 1912); and Álvaro Alonso Barba, Arte de los metales (La Paz, Bolivia: Artística, 1939).

(58.) Jerónimo de Sola y Fuente, Relacion, e informe, que haze el doc. D. Geronymo de Sola y Fuente, governador, que acaba de sèr de la villa, y mina de Guancavelica, y superintendente general del ramo de azogues en todo el reyno del Perù (Lima: Imprenta de la Plazuela de San Christoval, 1748).

(59.) Antonio de Ulloa, Relación de Gobierno del Real de Minas de Huancavelica (1758–1763), eds. Kendall W. Brown and José J. Hernández de Palomo (Lima: Banco Central de Reserva del Perú and Instituto de Estudios Peruanos, 2016).

(60.) Luis Capoche, Relación general de la Villa Imperial de Potosí, ed. Lewis Hanke, Biblioteca de Autores Españoles 122 (Madrid: Atlas, 1959); Pedro de Cieza de León, La crónica del Perú (Madrid: Espasa-Calpe, 1945); Nicolás de Martínez Arzanz y Vela, Historia de la Villa Imperial de Potosí, 1545–1577, riquezas incomparables de su famoso cerro, grandezas de su magnánima población, sus guerras civiles y casos memorables (Buenos Aires: Emecé Editores, 1943); and Pedro Vicente Cañete y Domínguez, Guía histórica, geográfica, física, política, civil y legal del Gobierno e Intendencia de la Provincia de Potosí [1791] (Potosí, Bolivia: Editorial Potosí, 1952).

(61.) Gonzalo Gómez de Cervantes, La vida económica y social de Nueva España al finalizar el siglo XVI, ed. Alberto María Carreno (Mexico City: José Porrua, 1944).