CHAPTER 2
Reconstructing the Environmental History of Colonial Mining
The Real del Catorce Mining District, Northeastern New Spain/Mexico, Eighteenth and Nineteenth Centuries
ANTONIO AVALOS-LOZANO AND MIGUEL AGUILAR-ROBLEDO
Often nothing is left of ancient societies but stones. Likewise, little is left of the social world of Mexican mining in the eighteenth and nineteenth centuries except the landscapes left behind. As this case study shows, the environmental effects of mining have indeed persisted long after mining ceased. The causes, though hidden in the past, can be inferred from methodically observing the clues that survive in landscape “palimpsests.” Landscapes are dynamic systems characterized by their hysteresis,1 which implies that their functioning and structure store information about the history that shaped them. A careful reading of the make-up of the flora, the structure of vegetation communities, the archaeological remains, the nature of local bio- and geochemical cycles, and the distribution of microclimates and eroded areas can provide information on the environmental history of Mexican mining.
This chapter offers a reconstruction of the environmental history of mining in the Real de Catorce Mining District—located in the southern part of the Chihuahuan Desert and overlapping the current Wirikuta protected area—in northeastern Mexico, from the 1770s through the 1820s, that is, from the final decades of colonial rule through the struggle for independence from Spain.2 Based on a methodology that combines tools borrowed from paleoecology, ecology, economic history, environmental history, environmental chemistry, process engineering, and climatology, this chapter analyzes the relations between industrial metabolism and the structure, composition, and dynamics of the landscapes in this region.
More specifically, by studying the balance of matter-and-energy, or the “industrial metabolism” of the Real de Catorce Mining District, much can be recovered from the past. This method allowed estimating the amount of silver produced, the type of minerals processed, the quantities mined, and the technologies and processes used, as well as estimates of the energy sources and inputs for every facet of the production process.3
Further, based on documentary research, remote sensing, and field surveys, it is feasible to track commercial routes, the place of origin of inputs and materials, and the volume and destination of residual output. These data also permit inferences concerning the impacts that the metallurgical-mining system had on ecosystems and its influences on the composition and dynamics of landscapes in the southern Chihuahuan Desert. The peculiarities of the industrial metabolism in the Real de Catorce metallurgical-mining systems help us understand the complexity of Mexican metallurgical processes.
This chapter is divided into six parts: first, we sketch the history of metal mining in Mexico and in the Real de Catorce, from colonial times through the early nineteenth century; second, we offer an overview of the structure of the Mexican silver industry; third, we examine the mining operations and processing of silver ores; fourth, we turn to the formation of mining landscapes in the Real de Catorce Mining District; fifth, we offer some descriptive results from our study; and sixth, we offer our conclusions.
HISTORICAL OUTLINE OF SILVER EXTRACTION IN MEXICO
From 1561 to 1640, the production of Mexican silver increased constantly, rising in gross terms from 1,004 metric tons in the period 1561–1580 to 1,764 metric tons in the period 1621–1640.4 After 1640, production declined as miners had to dig deeper to find rich ore. The factors that explain the fall in production can be summed up in one phrase concerning financing: “the mines, whose sterility is regretted for lack of loans and of capital.”5 Poorer ores limited investment, and limited investment further hamstrung silver production.
Fausto de Elhuyar, who served for thirty years as general director of mines in Mexico, wrote in 1825 that “in the eighteenth [century] the government began to open its eyes, and to recognize the wrong path it had until then followed.”6 According to one of the foremost historians of Mexican mining, David Brading, this new outlook on the part of Spain’s imperial authorities produced a “revolution in government” that translated into a series of changes in administration known as the Bourbon Reforms (1763–1810). Brading considers the reforms to be one of the driving forces shaping mining and metallurgy in the late colonial period, one that revolutionized the structure of silver production in Mexico.7 The innovations associated with the Bourbon Reforms spurred the economy, producing an unprecedented mining bonanza. The production of Mexican silver, which in the 1710s was 1,781 metric tons, rose to 5,985 metric tons by the 1790s.
However, this economic shake-up did not affect all the regions involved in the Mexican mining industry equally. Its effects were strongly felt in the fourteen mining towns (asientos de minas) that already contained 95 percent of Mexican silver production. This leads us to suggest that the ultimate causes of the great mining bonanza of Bourbon Mexico have been misidentified. It is conceivable that the Bourbon “revolution in government” was not the fundamental cause of the increase in silver production, but simply one of its consequences. The reforms certainly nurtured the bonanza in a virtuous circle, but were not the original source of the phenomenon. To attribute the enormous vigor of Bourbon mining primarily to the Crown’s reforms amounts to putting the cart before the horse. It was the increasing power, negotiating skill, and volume of business of the mining aristocracy that forced the government to introduce reforms. Even though it is difficult to fathom the complexity of the processes involved, the Bourbon Reforms can hardly be envisaged in the absence of a group of entrepreneurs with sufficient clout and capital to steer imperial policy in directions they preferred. They harbored daring plans of investing in scientific and technological development, including the financing of new mining and smelting techniques out of their own pockets, as well as pursuing new prospecting explorations. This led to the discovery of Catorce, a profuse mineral (or ore-bearing district) that in 1803 produced 92 metric tons of pure silver, which amounted to 16 percent of the total production of silver that year in Mexico.
The powerful miner-merchant families sent various lobbying missions to Spain and came to an agreement with the minister of the Indies, José de Gálvez, regarding the restructuring of the industry. With the support of some members of the government they stripped the laborers of a substantial part of their ore share (partido) and obtained exemptions from the payment of various duties. In this period, defined by a veritable reconquest of Mexico undertaken against the Creoles (Mexican-born whites), the reform-minded Crown found a group of essential allies in the rich merchants of Peninsular origin (Spanish-born). By the end of Bourbon rule, a handful of families had obtained, as a reward for their loyalty, control of fourteen of the most important mining districts in the country.
Several families dominated Mexican mining, notably the Borda and Fagoaga families at the national level and the Obregon y Parrodi family in Catorce.8 They were businessmen, founders of gigantic agro-industrial complexes.9 These family businesses were the greatest companies of their time in Mexico, characterized by the concentration and integration of their operations in mining, agriculture, and textiles.10 These companies were the true driving force of the Mexican economy and provoked crucial aspects of the Bourbon Reforms, overcoming the inertia into which mining had fallen.11 Under their influence Mexico underwent an industrial revolution that rationalized the idiosyncrasies of mining and smelting and reconfigured the industry’s social fabric. The Mining Court and School of Mines (Real Tribunal de Minería and Real Seminario de Minería), two institutions that were to become pivotal in the life of independent Mexico, were founded during this time, in the 1790s. The methods of extraction and processing of minerals were standardized. Several emblematic works of infrastructure were built. Old abandoned mining towns were reclaimed. The facilities built were so sophisticated that they allowed the reprocessing of tailings, grease, and slag.12
An important aspect of this revolution was the transformation of labor relations. The partido was reduced or eliminated,13 while some arrangements that had not been used for a hundred years, such as the repartimiento de indios (forced assignment of Indian labor) and the leva (forced recruitment of idlers) were put back into practice.14 The Crown had liberally resorted to forced labor throughout the long decline in population in Mexico, from the 1520s to about 1650. But with the population recovery well under way by the early eighteenth century, both practices had diminished to the point of insignificance. Then, late in the colonial era, in view of the new labor demand, they were reinstated by the Crown, which authorized them explicitly in the mining code of 1783.15
The main losers of this makeover were mine and hacienda laborers, as demonstrated by the multiple riots and the first recorded strike in North America, staged by the laborers of the Vizcaína mine in 1766. But little of this wealth really benefited the country, and none was even used to alleviate the suffering of Mexican society under emergency conditions. In 1784 more than 8,000 laborers—22 percent of the national mining labor force—died of hunger in the mining town of Guanajuato, the richest in Mexico, and more than 300,000 people died throughout the country because of the loss of maize crops as a consequence of frost.16 Alexander von Humboldt, who visited in 1803–4, was correct when he claimed that “Mexico is the country of inequality.”17
The conditions for mine workers and mining business only worsened with the uprising of 1810, which led to the end of colonial rule. For more than a decade armies crisscrossed the country, and instability undercut the economy. In 1821, after declaring independence, Mexico was bled of capital withdrawn from the country by the Spaniards. Real de Catorce, the second most important mining district and the district that had maintained operations despite the War of Independence, was abandoned, dragging down agriculture and commerce.18 The situation of the country was so pressing that in 1822 the Regency government issued a proclamation decreasing taxes on silver production from 13 to 3 percent. The monopoly of the colonial mint, the Casa de Apartado (facility where the gold was separated from the silver), was lifted, and the miners became free to separate gold from silver where and when they wished. Imports of quicksilver (mercury) were declared duty-free and miners were supplied with blasting powder at cost.19 The last important shift came in 1823 when those articles of the mining ordinances of 1783 were abrogated that barred foreigners from investing in Mexican mining or metallurgy.20 This decree allowed foreigners to form associations with Mexican citizens for the purpose of exploiting mines and smelting metal ores.
The British avidly took advantage of these reforms. They formally recognized Mexican independence and established diplomatic relations in 1825. They went on to invest more than 12 million pesos in only three years (1823–1826), through seven companies, notably the Anglo Mexicana Company in Catorce. This was the precursor to a farce that culminated in one of the worst financial disasters the City of London had faced in two hundred years.21
One company failed immediately, before even gaining a foothold in Mexico. The other six did establish themselves, though two failed by 1827. By the end of 1848, only the United Mexican Company survived, and in June 1849 it surrendered its interests to a company of Mexican investors and disappeared for good. The disaster was predictable, and its reasons obvious. When investing in Mexico, the English had not taken into account the effects of the prolonged War of Independence, the consequent dispersal of specialized workers, and the destruction of the country’s infrastructure. While those problems could perhaps have been solved, what had no remedy was the English contempt for Mexican experience and technology, the fruit of three hundred years of mining on the part of Mexicans.22
THE STRUCTURE OF THE MEXICAN SILVER INDUSTRY
In the late nineteenth century, Santiago Ramírez, a mining engineer and official at Mexico’s College of Mines, sketched the geology of Mexican silver. Roughly three thousand mines existed, working four or five thousand veins of silver or gold.23 Almost all of the deposits were found in veins. Silver ores were divided according to their matrix into metallic and earthy categories. The former included minerals of lead (galena) and copper (fahlerz, arsenical copper), blendes (sphalerite), and pyrites (pyrite and chalcopyrite). The latter were all those with a matrix of quartz, clay, iron oxide, or limestone.24
Most Mexican mines’ shallow veins had ores disseminated in ferruginous earth that the Europeans called the “iron cap,” or gossan. The ores were also called podridas (rotten) because they were easy to break up. In Mexico these oxidized ores were called colorados (reds) and owed their name to the iron oxides that imparted a reddish color to them. Normally, the colorados contained chlorides, bromides, iodides, and sulfides. Native silver was also found. The colorados generally contained low grades of silver ore, but were profitable because they were easy to dig and amalgamated well in perhaps the most common reduction process used, the patio process—in which silver ore was crushed; mixed with water, mercury, and other substances; and then dried. In Catorce, where the amount of colorados was extraordinary but the weather was cold and inconvenient for the patio process, other reduction processes were deployed.25
At greater depth the majority of Mexican veins consisted of reduced minerals such as sulfides, in particular pyrite, and other sulfosalts, in a matrix or gangue that was hard and resistant. Their excavation was very expensive. These ores were called negros (black), and from a metallurgical point of view they were considered very “unruly.” Ramírez states, as do other authors, that the grade of the silver ore increases with the depth of the vein.26 For this reason, Mexican miners endeavored to establish mining operations at the greatest possible depth.
The amount of colorados in Mexico was enormous,27 and in 1843, they contributed seven-eighths of the silver produced.28 Real de Catorce had an important advantage over other mining districts in that most of its mines extracted oxidized ores, which needed less investment for extraction and refining. Smelting was unimportant in Catorce. On the whole, Mexican silver ores were of disappointing quality. José Garcés y Eguía, a nineteenth-century Mexican chemical and mining engineer, calculated that the amount of ore treated in Mexico was no less than ten million hundredweights per year (460,250 metric tons/year), yielding 690 metric tons of silver (the quantity that, with some variations, was minted in Mexico in the last years of the eighteenth century).29 The average yield would thus have been 2.4 ounces per hundredweight, or 1.49 grams of silver per kilogram of ore.30 Elhuyar, for his part, estimated that the Mexican ores yielded on average three to four ounces per hundredweight, or 1.87 to 2.49 grams of silver per kilogram of ore.31 Other authors arrived at similar figures.32 These figures show that even though the grade usually increased with depth, ordinary Mexican mines were poor on average. Garcés y Eguía asserted that rich minerals (appropiate for smelting) contain at least 60 grams of silver for every kilogram of ore.33
Although the grade of silver ore extracted in Mexico did not change substantially between 1570 and 1884, some mines in Catorce represented notable exceptions that contained high grades of ore. For example, the Mina del Padre Flores in its first year of operations produced as much as 46 metric tons (worth 1.6 million pesos) from rich minerals containing more than 100 grams of silver per kilogram of ore.34
MINING AND PROCESSING SILVER ORES
By the late eighteenth century, silver mining was an elaborate technical process. Mexican miners had little difficulty recognizing where best to look for silver. Once the veins of metal were discovered, exploitation began. Mining operations spanned everything from hacking the ore from underground veins to loading mules that would carry it to the warehouse. Mining silver required thirty different specialized tasks.35 Considering that the grade usually increased with depth and that most Mexican veins were “inclined,” the miners’ work began with the construction (cuele) of a vertical shaft (tiro) that would converge with the vein at an approximate depth of 8 varas (6.68 m).36 The shafts were usually rectangular, but octagonal or hexagonal ones were also found.37 In 1732, José de Sardaneta introduced the use of tacos in Guanajuato for such construction activities.38 This technique, used in Europe since 1613,39 became indispensable and allowed the construction of shafts as deep as the one at La Valenciana, which in 1810 reached 531 meters below ground. Once the shaft reached deep enough, horizontal galleries (called laboríos) were built alongside the vein.40 As mandated by the ordinances, pillars of solid rock were left in order to support tunnels. All of the operations aimed at providing access to the mine were referred to as works of disfrute (benefit).
As the depth of shafts increased, new difficulties and costs arose. The eighteenth-century Mexican lawyer and intellectual Francisco Javier de Gamboa noted: “It is the waters that are the major peril of the mines. [. . . W]hen the veins of the mines are picked at, the water springs as does the blood from the body. [. . .] Of this curious law of physics only the mine owners experience the effect, watching their galleries [. . .] filling with more water the deeper they are.”41 At the outset, the miners solved this problem using a mule-drawn capstan or hoist called a malacate to drain the mines.42 Up to eight such capstans were placed in octagonal shafts in some mines where large volumes of water had to be removed. But some of the earliest colonial mining operations, where topography permitted, already preferred to use crosscuts, i.e., tunnels that would cut across the vein, connect the different shafts, and extract the water from the galleries by gravity.
John Percy, the father of English metallurgical literature, wrote in the preface to his Metallurgy of Silver and Gold (1880): “From all branches of metallurgy one that has silver as an object, is the most extensive and most varied and more complicated.”43 In the case of Mexico, the problems were even more complex, as the silver extracted from Mexican mines was of “various minerals.”44 In nature, silver can be found in native (metallic) form or combined with other substances. The silver can be an essential or a minor element in the different combinations of a mineral compound. In both cases, however, miners considered the compound a silver ore.45
It was crucial to establish as precisely as possible the nature of the bond that united silver with other elements, as this determined the choice of the method of processing the ore.46 Besides the type of mineral compounds present, their assay value (ley) must also be considered, or the quantity of metal per unit weight that they contained, on which the commercial value of the silver would depend.
The refining of silver in Mexico involved more than eighteen different specialized tasks.47 Different ores required different procedures. Costly mistakes could be made at each step. In 1640, the distinguished chemist and mining engineer Alonso Barba explained: “To add quicksilver [mercury, or azogue] to the metal that requires fire is to lose it. To toss into the furnace what is not for smelting, is to hinder, damage, and do nothing; and even within the boundaries of what is for quicksilver, and what for fire, there are differences and degrees of ease in processing.”48 Writing 160 years later, the German metallurgist Federico Sonneschmid (a member of the late-eighteenth-century German mission sent to Mexico by the king of Spain) confirmed Barba’s position on the indispensability of expertise: “Not all the minerals that contain silver are suitable for processing using the patio process of mercury amalgamation. The worker must [. . .] know [. . .] its qualities.”49 Sonneschmid’s contemporary Garcés y Eguía agreed on this point while dissenting on some specifics.50 For example, the former found pyrite-bearing minerals to “resist processing with quicksilver,” while the latter found them to be suitable for the patio process, based on mercury amalgamation. In their time Sonneschmid and Garcés y Eguía were the most enlightened experts in the art of metallurgy. They perfected or invented various processing techniques. Both had gained their outstanding experience in the everyday activities of Mexican mines and haciendas.
The medley of techniques and procedures confused Humboldt to such a degree that he came to consider Mexican metallurgists and mining engineers truly inept. Actually, it was Humboldt, despite his familiarity with mining and chemistry, who did not grasp the subtleties of such a difficult art, in which one had to take into account variable climatic conditions, the great chemical and physical diversity of the ores to be processed, and the varying quality of the available supplies. The master smelters and azogueros (quicksilver specialists) were indeed driven by necessity to use different processing techniques to achieve the same goal, but this was not due to ineptitude. These workers drew on the experience they acquired during work, as well as the preparation they were given by the Real Colegio de Minería, which certified them. As Humboldt observed:
The above separation of minerals [. . .] into those suitable and unsuitable for the patio process, seemed necessary to me in order to convey a general idea [. . .] but [. . .] at every step one shall find examples of unsuitable [. . .] minerals being profitably processed in the patio and [. . .] of other [. . .] suitable ones [. . .] from which not all silver content is extracted. These variable circumstances have different causes. A compact mineral [. . .] must react differently to the processing in a different way than one crushed [. . .] into fine particles [. . .] the very nature of the gravel exerts at times an influence, too.51
The same types of minerals had at times such a different composition that two samples of the same ore, obtained in the same mining town, could react differently to processing.
THE FORMATION OF MINING LANDSCAPES IN THE REAL DE CATORCE DISTRICT
The mining district of Real de Catorce is located in the Altiplano region of the current state of San Luis Potosí. It includes the municipalities of Catorce, Cedral, Villa de la Paz, and portions of the municipalities of Charcas, Matehuala, and Villa de Guadalupe covered by the Natural Protected Area of Wirikuta. The study area is located in the northern part of the Altiplano, and in the southeastern quadrant of the ecological region known as the Chihuahuan Desert.52 (See figure 2.1.)
FIGURE 2.1. The Real de Catorce mining district, San Luis Potosí, New Spain/Mexico, eighteenth and nineteenth centuries. Map by José de Jesús Izaguirre Hernández.
Mining activities have been carried out in the area since the end of the eighteenth century. A large strike occurred in 1778.53 From this moment onward, Catorce increased its production, reaching the point where it became the second most important colonial mining district, distinguished by a complex industrial metabolism that affected the composition, structure, and dynamics of the landscapes that sustained it in complicated ways.
By consulting primary sources, such as documents stored in the Mexican General Archive of the Nation and the Historical Archive of the San Luis Potosí State, we identified 124 mines that operated in the area and period under study, and the minerals obtained in each mine. The industrial facilities that operated in Wirikuta at the end of the eighteenth century and beginning of the nineteenth century were field-checked and mapped: besides the 124 mines, there were 79 processing haciendas with 644 mills (tahonas) and 248 cazos (amalgamating mills heated from below); 7 haciendas devoted to stock raising and crop cultivation; 2 estates for fattening cattle; 3 centers that supplied wood and charcoal; and 7 locales for the final disposal of residues.
In 1782, the mining town of Real de Catorce had 12 haciendas processing ore by smelting and in vats (148 tahonas, 58 vats): 4 in Ojo de Agua (70 tahonas, 25 vats); 1 in La Carbonera (24 tahonas, 13 vats); 7 haciendas processing in the patio, in vats, and by smelting in Cedral. In 1785, Matehuala had 28 haciendas processing in vats and with quicksilver, 13 by smelting, and 9 by galemes de mano (low-heat blast furnace).54
Sixty-six mines operated in Real de Catorce in 1794. The population of Real de Catorce rose to 15,000 inhabitants.55 Since on-site processing was becoming difficult due to the scarcity of water at the end of the eighteenth century, the majority of processing haciendas were established nearby in the Cañada de los Catorce, Laureles, Vanegas, Potrero, Cedral, and Matehuala.56 At that time, Real de Catorce had one smelting establishment with 9 furnaces and many small smelters (zangarros), whereas Los Catorce had 2 patio process haciendas, El Potrero had 4 and 4 zangarros, and El Cedral, the most important locality for processing, had 9 haciendas using the patio process and cazos and 11 using smelting.57
In 1800, the number of haciendas in Matehuala reached 14. Due to transportation costs, it was much less expensive to build haciendas near the mining town. It cost 4 pesos to transport one load of ore to San Luis Potosí (212 kilometers), while it cost one peso to Matehuala (85 kilometers).
The twentieth-century Mexican historian Montejano calculated that mines of Real de Catorce produced 104 million Spanish ounces of silver between 1773 and 1827 (each Spanish ounce was 28.7 grams; thus 2,990 metric tons).58 However, as in the rest of the country, the grade of the silver from Catorce mines was quite low: San Agustín produced 14 ounces per load, San Gerónimo 4, La Purísima and Santa Ana each 3.5, and the rest between 1.5 and 2. Some mines in Catorce represented a notable exception: for instance, Padre Flores produced 129 ounces per load. Considering that the average yield of Catorce ores was 7.2 ounces per load and each load was equal to 37.26 kilograms (104 million ounces divided by 7.2 ounces per load is equal to 14.44 million loads, multiplied by 37.26 kilograms), the quantity of ore extracted in Catorce between 1773 and 1827 was 538,200 metric tons.59
It appears that at the beginning of the nineteenth century the composition of the ores extracted in Real Catorce began to change. Between 1778 and 1803, extraction focused on the colorados, the “the weathered near-surface deposits, with metal in its native state (native silver and chlorargyrite).”60 Later on, miners turned to the negro, or pyrite- and copper-bearing, ores. It is possible that the processing (i.e., industrial) activities—and therefore the industrial metabolism, frontier relations, and patterns of ecological disturbance—underwent modifications required by changes in the ores being processed. The shift to deeper ores, for example, likely led to an increase in charcoal demand for smelting and the formation of toxic residues such as sulfur dioxide, arsenic trioxide, and lead.
In 1803 the annual output of the mines of Real de Catorce was 92 metric tons of pure silver, which amounted to 16 percent of all Mexican silver production (575 metric tons per year). If we take into account the percentages of the silver processed in San Luis Potosí and the portion corresponding to Catorce, we arrive at the following numbers: silver obtained by amalgamation, 98.39 percent; silver obtained by smelting, 1.61 percent. Between 1773 and 1827, 529,534.98 metric tons of ore were processed by amalgamation, and 8,635.02 metric tons by smelting.
Silver mining and processing spawned a suite of associated businesses needed to provide supplies. In the mining towns of Real de Catorce and La Maroma, most of the processing was in amalgamating mills heated from below (cazos) and fondón de a caballo (a giant rotating metal plate over a fire, driven by a horse), because of the type of minerals and because the cold weather made the patio process inefficient.61 Different processes were used in Cedral, Matehuala, and San Bartolo due to the different mineral composition of the ores mined in each place. The variety of processing techniques called for various supplies. In addition to fuel, food, and fodder for miners and their animals, water and wood for construction were also needed. In this way, mining encouraged the development of other economic activities in Real de Catorce, such as agriculture and commerce.
Food, for example, was increasingly grown locally. The reason was simple. According to Humboldt, in 1803 the average price of a fanega of maize grown in Salamanca (Guanajuato state) varied as follows: where it was produced, in Salamanca it cost fourteen reales (one peso and six reales), in Querétaro (at a distance of 84 kilometers from Salamanca) two and a half pesos, and in San Luis Potosí (at a distance of 178 kilometers from Salamanca) four and a half pesos.62 Humboldt did not mention the cost of maize in Real de Catorce, but it can be imagined, because Real del Catorce is 349 kilometers from Salamanca. Given that necessity is the mother of invention in every industry, the high price of imported food awakened the ingenuity of the inhabitants. “Men began to till the soil in the valleys and slopes of the surrounding mountains,” Humboldt noted, “and everywhere where the rock was covered with mulch. Farms were established in the vicinity of mines to remedy the shortage of food and the considerable price reached by all agriculture products.”63
Not only food became more expensive. The price of other supplies indispensable for the operation of the industrial system rose too: hides, goat tallow, ixtle and pita (fibers derived from yucca and agave), charcoal, liquor. This led to the development of various types of haciendas in the vicinity devoted to production of these and other items. They sometimes used sophisticated irrigation techniques, such as what in the Middle East are called qanats (known in Spanish as galerías filtrantes), underground channels carved through rock. These haciendas helped make the goods needed to sustain mining operations more affordable than they could have been if imported from afar. Moreover, the discovery in 1561 of the salt flats of Peñón Blanco, located between Zacatecas and San Luis Potosí, and their subsequent exploitation guaranteed the supply of salt at Real de Catorce at modest prices. Salt—some 78,000 metric tons between 1773 and 1827—was used in silver processing.64
The impact that the mining and smelting industry had on the landscapes of the mining district of Real de Catorce in the eighteenth and nineteenth centuries has long interested observers and scholars.65 Most authors on the subject claim that the ecosystems suffered terrible degradation that affected the entire district and provoked the transformation of grassland into scrubland. All of this speculation draws on a catastrophic perspective, based on an analysis carried out in 1827 by H.G. Ward, an agent of a British mining firm. Ward described the Sierra de Catorce in 1827 in strong terms: “There is not a single tree or a single blade of grass in the vicinity; and yet fifty years ago the district was covered by forest. [. . .] Whole forests were burned to clear the land and timber larger than required for the mines is brought from a distance of twenty-two leagues [92.18 kilometers].”66 Ward based this assessment on reports from the colonial commissioner Silvestre López Portillo, written in 1779 (fifty-four years earlier) in which he described the region, in particular the land close to the San Bartolomé River, located 30 kilometers from Real de Catorce: “[Along the] San Bartolomé river, which springs and disappears in the most interior and gullied parts of these mountains, [. . .] there is an impenetrable oak- and pinewood of such imponderable corpulence [. . .] that they may be compared with the mountains.”67
But a careful reading of the report allows us to understand that Ward was wrong in his interpretation of López Portillo’s document. The truth is that the commissioner described a place on the eastern slopes of the Sierra, 30 kilometers away from Real de Catorce, which even today supports a thriving oak and pine forest located on the eastern slope, a wet adiabatic and more fertile zone. Ward did not even know the area and mistook the drier northwest slope for the more humid eastern slope.
Ward was not the only one to draw hasty conclusions about vegetation history in the vicinity of Real de Catorce. More recently, scholars, including González-Costilla, Giménez de Azcárate, García, and Aguirre Rivera, state on the basis of secondary sources: “Thus, before the onset of mining operations, in the last quarter of the 18th century, the Sierra was almost uninhabited and covered by luxuriant forests, which supplied abundantly the haciendas and mines. [. . .] Fifty years on, close to 1825, there was neither tree nor scrub left.”68 However, a detailed analysis of their main source, a study by Montejano of the mines of Real de Catorce, allows us to locate only isolated references to the subject, so scant that they make impossible any reliable inference about the vegetation of the Sierra.69 Montejano only cites others, who in turn repeat Ward’s statement from 1827. Those descriptions clearly impel us toward the easy conclusion that the mining and smelting processes developed in Catorce provoked, in only fifty-four years, a complete loss of the productive potential of the surroundings.
But the reality could have been quite different. Other sources provide more information, such as the reports of Silvestre López Portillo and Bruno de Ureña of 1779;70 those of Ward himself on the San Cristóbal plain, written in 1826; and those of Robert Phillips from 1826.71 From these and other sources it is possible to put together the structure and composition of the landscapes of Wirikuta at the beginning of the nineteenth century.
Four essential documentary sources, from 1779, 1779, 1822, and 1826, allow us to reconstruct local landscapes in the Real de Catorce area. Francisco Bruno de Ureña, a charted surveyor, covered the San Cristóbal plain, to the west of the Sierra de Catorce, in 1779, describing the vegetation. On the basis of the common names used in the document, it has been possible to reconstruct the vegetation communities present. From this, we infer the presence of microphyllous scrub in the San Cristóbal plain, with the presence of Flourensia cernua and Larrea tridentata.72 In 1779, Silvestre López Portillo described the forests of the eastern slope of the Sierra up to the piedmont: “There is wood of all sizes, in some parts pines, in others oaks, as well as various other kinds, so that it is very abundant in fuelwood, and in mesquite for charcoal. Though not present in the Sierra itself, they abound on its [lower] slopes.”73
Nearly fifty years later, Ward described the northern part of the same San Cristóbal plain, mentioning that a microphyllous scrub dominated: “[A] small shrub [. . .] which cannot be other than la gobernadora, and mesquites and dwarf palms (Yucca), with a fruit that is not very different from the dates.”74 Bustamante, an early-nineteenth-century Mexican scientist and influential scholar, wrote in April 1824: “An herb called gobernadora was found there [at Catorce]. It is abundant in the whole Sierra and is very resinous, giving a very vivid flame.”75
These observations from men who had surveyed the region with their own eyes support the conclusion that the mining and smelting processes developed in Catorce between 1779 and 1827 did not provoke the loss of the region’s productive potential. Further, the cited documentary evidence shows that the northwest slope of the Sierra de Catorce had dry-climate vegetation before the discovery of the mines, that the effects of industrial activities were superimposed on vegetation changes of a different nature provoked by a series of climatic phenomena—alternating cycles of drought and heavy rainfall, accompanied by heavy flooding. These natural changes aggravated the industrial impact. Several sources attest to some extreme climate events in the region and in Mexico as a whole toward the end of the eighteenth century.
HEALTH AND ENVIRONMENTAL PROTESTS IN THE CONTEXT OF SILVER PROCESSING
In consulting archival documents, we have discovered social movements focused on the health threats posed by metallurgical processes. For example, in 1827, when Juan Kidell of the Catorce Company asked the mining district authorities (diputación de minería) to intervene because the town council of Cedral had forbidden his company to “burn” (remove sulfur from) the minerals extracted at Sereno, the council argued that smoke from his two furnaces harmed the local residents. The mining district officials appealed to the governor, accusing the council of weak-mindedness and described its position as a case of “the most vile ingratitude and shamelessness that the residents should complain about the harmful qualities of the smoke.”76 This incident ended with the shutdown of the Catorce Company.
Documents from the period reveal two opposed positions about health threats caused by metallurgic processes: an official stance held by scientists with ties to the Spanish Crown; and another, which we call “independent.” One example of the official position is found in the writings of Sonneschmid, the German scientist hired by the Crown but whose research was financed by one of the great mining families of Mexico, the Fagoagas. Sonneschmid wrote: “It is noteworthy in the entire kingdom that the patio process is not a harmful operation for peons working in it, and [. . .] there would be no need for its mention, were it not for many Europeans who have let themselves be persuaded that [. . .] the refining of minerals destroys [the health of] an immense number of inhabitants.”77 However, Sonneschmid contradicted himself when he wrote about the process of distilling mercury, a necessary precursor to silver refining by amalgamation. He noted that the clay pots used to hold mercury often broke and put workers in grave danger. Referring to damage to the nervous system from mercury exposure, he wrote that he “found a number of people who [. . .] have azogado [shaking; original emphasis]. However from this they recovered fully, only retaining a slight tremble in their extremities.”78
Sonneschmid, even when he admitted the existence of harmful health effects of working with mercury, sought to minimize them. Humboldt took a similar position:
Around five to six thousand people are working in mineral amalgamation or the preceding processes. A great number of these [. . .] spend their life barefoot on mounds of ground metal [. . .] mixed with [. . .] oxidized mercury [. . .] and it is curious to see that [. . . they] have the best health. Physicians [. . .] unanimously declare that afflictions of the nervous system are rarely seen.79
Other knowledgeable authors saw the risks of mercury as genuine. Gamboa wrote of “frequent diseases [. . .] poisonous foundries, and azoguerías: incurable, and everywhere illnesses, amidst moisture, fire and vapors.”80 José Antonio Alzate, an early-nineteenth-century Mexican scientist and influential scholar, referred to “the azogue’s poisonous fumes.”81 Contemporary observers remained divided about the health effects of processing silver with mercury.82
Notwithstanding divided opinion on mercury, authorities in the late eighteenth century understood the principle of pollution when it came to drinking water. Legislators of the time possessed enough information to point out its dangers, as proven in 1783 by the Reales Ordenanzas [. . .] del Importante Cuerpo de la Minería de Nueva-España (Royal Ordinances [. . .] of the Important Mining Corps of New Spain [Mexico]):
Title 13. Of the supply of water and provisions for mining. Article 1. Given that drinking water is of first necessity in the mining districts [. . .] I order [. . .] that water infected with mineral particles shall not be used. Article 2. I prohibit with utmost rigor the diversion of waters from the drains [. . .] of the patios of haciendas and smelting furnaces into arroyos or aqueducts that carry it toward settlements.83
Humboldt’s testimony implies that the law was ignored, at least in some places.84 He relates that some of the inhabitants of Guanajuato drank the same water used for washing (in smelters) without suffering health impairment, despite the Royal Ordinances.
Although laws might be ignored, sometimes courts ruled in favor of communities claiming damage from mining operations, as demonstrated by the case recorded in Pachuca (modern-day Hidalgo State) in 1764. Pablo Aparicio was running a smelting furnace whose smoke and dust harmed his neighbors. According to the neighbors, the smoke killed their animals. On top of this, they claimed, the smelter polluted the nearby river with residues. Aparicio requested that the authorities ask the neighbors to buy back his facilities, but the final verdict obliged the accused to remove the furnaces, clean up the river, and leave the people in peace.85
On other occasions, however, community resistance to smelting haciendas was defeated. In a case from Chihuahua in 1732, authorities ultimately ruled in favor of the mining interests. Two mining entrepreneurs began constructing new furnaces at two sites. A group of local residents soon lodged a formal complaint before the city council (cabildo). The movement demanded halting the construction of the furnaces, which were located less than 170 meters from dwellings, and a commitment by the cabildo to prohibit the building of any furnaces in the environs of the city, because of the potential risks posed by their use. The complaint claimed: “No one should be compelled to put his life in grave danger coming [to prevent] the harm that others may suffer, and less still if it is [only] to augment someone’s income and profits; for better reason still [the interests] of an individual should not be put ahead of those of the health and well-being of a community that should watch and procure its own preservation.” One of the entrepreneurs appealed immediately, citing the tax revenue that his furnaces would bring to the Crown. The result, after many detours, was the approval of the haciendas and the defeat of the movement, which ended up opposing an accomplished fact, as the construction of the furnaces was furtively completed while the government consulted the opinion of physicians and scientists.86
THE INDUSTRIAL METABOLIC COMPLEX IN THE REAL DE CATORCE DISTRICT
A few calculations and estimates help to corroborate the impressions gleaned from the textual evidence concerning the influence of the mining and smelting industrial system in the formation of local landscapes. Let us begin with wood. Between the 1770s and 1827, a total of about 118 square kilometers (km2) of forest were cleared for the following activities: 85.39 km2 were used in the making of charcoal for smelting; 10.66 km2 were consumed as fuelwood in fifty-five processing haciendas; and 21.97 km2 were used for domestic consumption. These calculations were carried out using the data for silver production reported by Garcés y Eguía and taking into account the yield of wood and its dry weight (830 kg/m3) according to the numbers used by Salazar.87 The yield from a hectare of twenty-five-year old forest growing on poor soil was also factored into our calculations. This quantification does not include the wood required for the construction of ground supports, piles, and other artifacts, which from very early on was brought from distances exceeding 100 kilometers, as indicated by Ward.88
Ground truthing and the analysis of satellite imagery revealed that the estimated cleared area matches closely a zone that today stands out due to intensive erosion and desertification. Figure 2.1 shows the relationships between the different vegetation communities, the identified and mapped elements of the mining and smelting system, and the desertified areas. In 1827, Manuel Mier y Terán implied large impacts from mining’s industrial activities on the pine- and oakwood communities when he wrote that out of a total of 8,000 inhabitants of Real de Catorce, 5,750 devoted time to hauling fuelwood and charcoal to be sold in the city or at the silver haciendas.89
It is also possible to estimate the number of animals needed to produce silver in the Real de Catorce region. In an average year, some 10,000 beasts of burden, mainly mules, worked in the mines and in ore processing—especially the patio, fondón de a caballo, and the rotation of the horse capstan. These animals consumed an estimated 14,675 metric tons of maize annually. Roughly 8,000 hides of young bulls were used annually, as well as 57.5 metric tons of tallow rendered from 100,000 goats. More than 4,000 sheep and 400 cattle were slaughtered each year for human consumption. The herds that supplied the region, had they roamed freely, would have required more than 5,000 square kilometers of pasture.
Finally, in addition to the wood and animal requirements of silver mining and processing, one can estimate the pollution legacy at Real de Catorce.90 As noted above, on the basis of the calculations derived from the balances of matter and energy, we have determined that between 1773 and 1827 more than 529,534.98 metric tons of ore were processed by amalgamation and 8,635.02 metric tons by smelting.91 Taking as a reference the average grade of 7.2 ounces of silver per 37.26 kilogram of ore, we can estimate that a half million metric tons of tailings containing lead, arsenic, antimony, and silver were released into local ecosystems.92 So were more than 125,000 metric tons of salt, between 6,000 and 37,500 metric tons of copper sulfate, and 1,250 metric tons of mercury.93 All of these pollutants are still lodged in different environmental matrices in the region.
CONCLUSION
From 1770 to 1827, the deforestation, erosion, and disturbance of the Wirikuta landscape affected mostly the northern part of the Sierra de Catorce. These disturbances were not exclusively a consequence of mining and industrial activities. Climatic anomalies (intense droughts followed by violent rainfall) occurred at the end of the eighteenth century and magnified the industrial impact.
It is evident that the authorities and broad sectors of society were aware of the environmental and health effects of silver mining and processing. People living close to silver-refining industries complained of damage to their health, and authorities in colonial Mexico sometimes sided with them and other times with the mining interests. It is clear that many people found the evidence for ill health effects, especially of silver processing, convincing. Indeed, Mexican mining and metallurgical engineers altered technologies in ways that reduced health risks, though perhaps motivated mainly by a desire to conserve mercury. Nonetheless, power distribution inequalities allowed risky activities, ignoring demands on behalf of the possible victims.
During the late eighteenth and early nineteenth century, the emphasis of Mexican institutional policies rested mainly on selfish and short-term economic interests. Even though authorities in late colonial Mexico often observed cautionary principles when regulating the mining sector, the solution to social problems arising from the operation of potentially dangerous installations still had to answer to power relations. Support given by institutions to research caused some experts to be at the service of large capitalist interests or to be driven by cost-benefit criteria, privileging economic growth over community safety.
The incredible bonanza in Mexican silver production from the late eighteenth century to the insurrection of 1810 constituted an insurmountable barrier to the implementation of cautionary policies. These implementation efforts could not withstand the force of financial imperatives. The colonial government, and the independent one that followed after 1821, needed revenue desperately and saw the silver-mining industry as its best chance to obtain it. So both governments focused on drawing investors into mining almost at any cost. Accordingly, the health of ecosystems and human populations came in a distant second among governmental priorities. In these respects, the history of mining at Real de Catorce and in Mexico generally before 1827 resembled that elsewhere in North America in the centuries yet to come.
NOTES
The authors wish to thank the Multidisciplinary Graduate Program on Environmental Sciences, the Faculty of Social Sciences and Humanities, and the Faculty of Agronomy and Veterinary, Autonomous University of San Luis Potosí, for all their support for the research reported in this chapter; we also thank the anonymous referees for their insightful comments and suggestions; the editors, J.R. McNeill and George Vrtis, who generously helped to improve this chapter all the way from the first to its final version; Aleksander J. Borejsza, who translated the Spanish manuscript into English; and José de Jesús Izaguirre Hernández, who drafted figure 2.1. Of course, although these institutions and persons share any merit this chapter might have, the authors stand alone for its shortcomings.
1. Hysteresis is the character of a system that becomes manifest after disturbance. Even though the cause of the disturbance is no longer there, the system does not return to its original state. It stores a memory of its history, and of the path of disturbance.
2. Strictly speaking, Mexico was called the Viceroyalty of New Spain from its inception in 1521 until 1810, but for the sake of brevity we will call it Mexico throughout.
3. Miners refers to owners of mines; operatives to workers. This was the meaning of these terms in the mining industry of the study period.
4. Francisco de Elhuyar, Memoria sobre el influjo de la minería en la agricultura, industria, población y civilización de la Nueva-España en sus diferentes épocas, con varias disertaciones relativas a puntos de economía pública conexos con el propio ramo. Madrid, México: Imprenta de Amarita. Consejo de Recursos Naturales No Renovables. Ed. Facsimilar. (1964) [1825]: 47.
5. Francisco Javier de Gamboa, Comentarios a las Ordenanzas de Minas. México: Imprenta Díaz De León y White México. Miguel Angel Porrúa. Ed. Facsimilar. (1987) [1761]: 3.
6. Elhuyar, Memoria sobre el influjo de la Minería, 53.
7. D. Brading, Mineros y comerciantes en el México borbónico (1763–1810). (R.G. Ciriza, Trad.) México: Fondo de Cultura Económica. (2004): 57, 201.
8. F. Langue, Los señores de Zacatecas. Una aristocracia minera del siglo XVIII novohispano. México: Fondo de Cultura Económica. (1999): 50.
9. S. Sánchez, La minería novohispana a fines del periodo colonial. Una evaluación historiográfica. Estudios de Historia Novohispana (27), 123–64: 132.
10. F. Langue, Los señores de Zacatecas, 114.
11. Elhuyar, Memoria sobre el influjo de la Minería, 49.
12. Sánchez, La minería novohispana, 131–32.
13. “In Guanajuato, Catorce, Zacatecas and Real del Monte, once the worker completed his daily quota of mineral, called tequio, he would get from 50 to 30% of the additional ore extracted during the rest of the day” (Brading, Mineros y comerciantes, 202). The proportion varied in other mining towns. Debt peonage was common and prompted several laws that limited loans to four to eight months of wages (P.J. Bakewell, Minería y sociedad en el México Colonial Zacatecas, 1546–1700. México: Fondo de Cultura Económica. [1997]: 177).
14. S. Sánchez, La minería novohispana, 131–32.
15. Brading, Mineros y comerciantes, 201.
16. Alejandro de Humboldt, Ensayo Político sobre el Reino de la Nueva España (Séptima ed.). México: Editorial Porrúa. (2004): 48–49, 251.
17. Ibid., 68.
18. H.G. Ward, México en 1827. México: Fondo de Cultura Económica. (1995): 346.
19. Ibid.
20. R. Randall, Real del Monte. Una empresa minera británica en México. México: Fondo de Cultura Económica. (2006): 41.
21. Ward, México en 1827, 357–58.
22. Ibid., 357.
23. Santiago Ramírez, Noticia Histórica de la Riqueza Minera de México. México: Oficina Tipográfica de la Secretaría de Fomento. (1884): 65.
24. L. Carrión, Metalurgia por vía seca del plomo, plata, cobre, mercurio y oro. Pachuca: Tipografía del Gobierno del Estado. (1900): 35.
25. Ramírez, Noticia Histórica de la Riqueza Minera de México, 79.
26. Ibid., 80.
27. Humboldt, Ensayo Político sobre el Reino de la Nueva España, 341.
28. S. Duport, Métaux Précieux au Mexique Considérée Dans ses Rapports Avec La Géologie. La Métallurgie et L’Économie Politique. Paris: Chez Firmin Didot Frères, Libraires. (1843): 29.
29. Joseph Garcés y Eguía, Nueva Teórica y Práctica del Beneficio de los Metales de Oro y Plata. México: Imprenta de Díaz de León y White. (1873): 105–8.
30. Humboldt, Ensayo Político sobre el Reino de la Nueva España, 341.
31. Ramírez, Noticia Histórica de la Riqueza Minera de México, 36.
32. Duport, Métaux Précieux au Mexique, 143–44.
33. Garcés y Eguía, Nueva Teórica y Práctica del Beneficio de los Metales de Oro y Plata, 78.
34. Humboldt, Ensayo Político sobre el Reino de la Nueva España, 359.
35. Doris Ladd, The Making of a Strike. Mexican Silver Workers’ Struggles in Real del Monte, 1766–1775. Lincoln: University of Nebraska Press. (1988): 7.
36. One vara equals 0.836 meters (Humboldt, Ensayo Político sobre el Reino de la Nueva España, CXLIV).
37. Francisco de Sarría, Ensayo de Metalurgia o descripción por mayor de las catorce materias metálicas, del modo de ensayarlas, del laborío de las minas, y del beneficio de los frutos minerales de la plata. México: Impreso por D. Felipe de Zúñiga y Ontiveros. (1784): 86.
38. Tacos in this context were paper cartridges filled with black gunpowder and tied together with ixtle fiber and sealed with bentonite. Ladd, The Making of a Strike, 10.
39. Daubuisson, cited in Humboldt, Ensayo Político sobre el Reino de la Nueva España, 366.
40. Sarría, Ensayo de Metalurgia, 86.
41. Gamboa, Comentarios a las Ordenanzas de Minas, 353.
42. Ramírez, Noticia Histórica de la Riqueza Minera de México, 622.
43. Percy quoted in H. Collins, Metallurgy of Lead & Silver, Part I. Lead. Edited by W.C. Roberts-Austen, K.C.B., D.C.L., F.R.S. London: Charles Griffin & Company, Limited. (1900): v.
44. Humboldt, Ensayo Político sobre el Reino de la Nueva España, 337.
45. Collins, Metallurgy of Lead & Silver, Part I, 19.
46. Ibid.
47. Ladd, The Making of a Strike, 7.
48. Barba, Arte de los Metales en que se Enseña el Verdadero Beneficio de los de Oro y Plata por Azogue. El modo de Fundirlos Todos, y como se han de refinar, y apartar unos de otros. Madrid: En la oficina de la Viuda de Manuel Fernández, Casa C. Bermejo. Ed. Facsimilar. (1932) [1770]: 73.
49. F. Sonneschmid, Tratado de la amalgamación de Nueva España. México: Sociedad de Exalumnos de la Facultad de Ingeniería, UNAM. Ed. Facsimilar. (1983) [1825]: 54–56.
50. Garcés y Eguía, Nueva Teórica y Práctica del Beneficio de los Metales, 77–78.
51. Sonneschmid, Tratado de la amalgamación de Nueva España, 54–57.
52. Onésimo González-Costilla, Relación entre Bioclima y Vegetación en la Sierra de Catorce y Territorios Adyacentes (Altiplano Norte del Estado de San Luis Potosí, México), Tesis doctoral. Universidad Computlense de Madrid, Facultad de Farmacia, Departamento de Biología Vegetal II. (2005): 1.
53. Humboldt, Ensayo Político sobre el Reino de la Nueva España, 359.
54. G. Palmer, Real de Catorce: Articulación Regional, 1770–1810. San Luis Potosí, SLP: El Colegio de San Luis. (2002): 84.
55. Rafael Montejano y Aguiñaga, El Real de Minas de la Purísima Concepción de los Catorce, SLP. (Tercera ed.). San Luis Potosí, SLP: Academia de Historia Potosina, AC. (1974): 43.
56. Ibid., 173.
57. Ibid., 174.
58. Ibid., 172.
59. Humboldt, Ensayo Político sobre el Reino de la Nueva España, 341.
60. Modesto Bargalló, La química inorgánica y el beneficio de los metales en el México prehispánico y colonial. México, DF: Facultad de Química de la Universidad Nacional Autónoma de México. (1966).
61. A variation on the method of hot (vat) amalgamation developed in Catorce in the last decade of the eighteenth century by Miguel de Aguirre. It employed an enormous copper disk that rotated on a set of ovens, propelled by a horse.
62. Humboldt, Ensayo Político sobre el Reino de la Nueva España, 252.
63. Ibid., 238.
64. Montejano y Aguiñaga, El Real de Minas de la Purísima Concepción de los Catorce, 4.
65. Ibid.; Onésimo González-Costilla, Joaquín Giménez de Azcárate, José García Pérez, and Rogelio Aguirre Rivera, Flórula Vascular de la Sierra de Catorce y Territorios Adyacentes, San Luis Potosí, México. Acta Botanica Mexicana (78): 1–38. (2007); Palmer, Real de Catorce: Articulación Regional, 1770–1810. (2002).
66. Ward, México en 1827, 587.
67. Silvestre López Portillo, Documento de peritaje en el Real de Nuestra Señora de la Concepción de Guadalupe de Alamos, en catorze de Agto de mis setecientos setenta y nueve años, quoted in Primo Feliciano Velázquez, Colección de documentos para la historia de San Luis Potosí. (Prima Feliciano Velázquez, Comp.) (1987) [1779]: tomo 3, p. 480.
68. González-Costilla, Giménez de Azcárate, García, and Aguirre Rivera, Flórula Vascular de la Sierra de Catorce (2007): 3.
69. Montejano y Aguiñaga, El Real de Minas de la Purísima Concepción de los Catorce.
70. Velázquez, Colección de documentos para la historia de San Luis Potosí, 395, 481, 489.
71. Robert Phillips, Detalles de un viaje desde Altamira a Catorce (Serie Cuadernos 28 ed.). San Luis Potosí, SLP: Biblioteca de Historia Potosina. (1973).
72. Velázquez, Colección de documentos para la historia de San Luis Potosí, 395.
73. López Portillo, Documento de peritaje en el Real de Nuestra Señora de la Concepción de Guadalupe de Alamos, tomo 3, p. 481.
74. Ward, México en 1827, 607.
75. Carlos M. Bustamante, Carlos María, Diario Histórico de México, 1822–1848. México: Centro de Investigaciones y Estudios Superiores en Antropología Social, Colegio de México, 2003.
76. Archivo Histórico de San Luis Potosí, Secretaría General de Gobierno, 1826, February 14, 1827.
77. Sonneschmid, Tratado de la amalgamación de Nueva España, 94.
78. Ibid., 51.
79. Humboldt, Ensayo Político sobre el Reino de la Nueva España, 49.
80. Gamboa, Comentarios a las Ordenanzas de Minas, 463.
81. Alzate, Elogio Histórico del Sr. D. Francisco Javier de Gamboa Regente que fue de esta Real Audiencia de México. Gaceta de Literatura de México. 373–84. (1831): 380.
82. Luis Chávez, La situación del minero asalariado en la Nueva España a fines del siglo XVIII. México: UCPEET/STPS. (1987): 48–49.
83. Reales Ordenanzas para la Dirección, Regimen y Gobierno, del Importante Cuerpo de la Minería de Nueva España y de su Real Tribunal General. De orden de su Mejestad. México: Sociedad de Exalumnos de la Facultad de Ingeniería. Ed. Facsimilar. (1979) [1783]: 134–35.
84. Humboldt, Ensayo Político sobre el Reino de la Nueva España, 49.
85. Ladd, The Making of a Strike.
86. B. Hausberger, Una iniciativa ecológica contra la industria minera en Chihuahua. Separata de: Estudios de Historia Novohispana. (1993) [1732]: vol. XIII, pp. 116–34: 4–5.
87. Garcés y Eguía, Nueva Teórica y Práctica del Beneficio de los Metales; Guadalupe Salazar, Las haciendas en el siglo XVII en la Región Minera de San Luis Potosí. San Luis Potosí, México: Universidad Autónoma de San Luis Potosí. (2000): 38.
88. Ward, México en 1827, 587.
89. Manuel Mier y Terán, 1827, as quoted in Montejano y Aguiñaga, El Real de Minas de la Purísima Concepción de los Catorce.
90. Ward, México en 1827, 338, 375, 601.
91. Elhuyar, Memoria sobre el influjo de la Minería, 90.
92. Humboldt, Ensayo Político sobre el Reino de la Nueva España, 341, 372.
93. Garcés y Eguía, Nueva Teórica y Práctica del Beneficio de los Metales, 108.