Potosí, known as Villa Imperial de Potosí in the colonial period, is the capital city and a municipality of the Department of Potosí in Bolivia. It is one of the highest cities in the world at a nominal 4,067 m (13,343 ft). Diego Huallpa, an indigenous prospector, is traditionally credited with the discovery of the Cerro Rico in 1545, which led to the founding and rapid growth of Potosí due to its extraordinary silver wealth.
The silver boom
Founded in 1545 as a mining town, it soon produced fabulous wealth, and the population eventually exceeded 200,000 people. The city gave rise to a Spanish expression, still in use: valer un Potosí ("to be worth a Potosí"), meaning "to be of great value". The rich mountain, Cerro Rico, produced an estimated 60% of all silver mined in the world during the second half of the 16th century. Potosí miners at first mined the rich oxidized ores with native silver and silver chloride (cerargyrite) that could be fed directly into smelting furnaces.
Especially successful were the small clay "flower pot" furnaces called guayras, which had been used by the Incas. By 1565, the miners had exhausted the direct-smelting ore, and silver production plummeted. Silver production was revived by the introduction of the patio process, invented by Spanish merchant Bartolomé de Medina in 1554. The patio process used mercury amalgamation to extract silver from lower-grade ores, and those containing silver sulfide (argentite), as was typical of the unoxidized ores found deeper in the mountain.
In 1609, another mercury amalgamation method, the pan amalgamation process was invented in Potosí, and proved better-adapted to the conditions at Potosí. Spanish American mines were the world's most abundant sources of silver during this time period. Spanish America's ability to supply a great amount of silver and China's strong demand for this commodity which the Spanish supplied via Latin American trade with the Philippines using the Manila Galleons, resulted in a spectacular mining boom.
Labor beneath the mountain
Indigenous laborers were required to work in Potosí's silver mines through the Spanish mita system of forced labor, based on an analogous mit'a system traditional to pre-Hispanic Andean society (though the mit'a directed labor for public works and collective agricultural projects). Laborers were drawn from the native population of an area that encompassed almost 200,000 square miles. Thirteen thousand men were conscripted each year, constituting about one out of every seven adult males in the indigenous population. These mitayos faced harsh conditions in the mines, where they were often given the least desirable jobs. While more skilled laborers extracted the ore, mitayos were tasked with carrying it back to the surface in baskets, leather bags, or cloth sacks.
The ore loads often weighed between 100 and 300 lbs, and the workers had to carry them up rickety ladders in steep, narrow shafts lit only by a candle tied to their foreheads. Many of them died or were seriously injured due to falls, accidents, and the harsh conditions of the mine life. Illness was another danger: at such a high altitude, pneumonia was always a concern, especially given the extreme and rapid changes of temperature experienced by workers climbing from the heat of the deep shafts to the freezing elements of the surface at 16,000 feet, and mercury poisoning took the lives of many involved in the refining process.
A colonial city and global connections
Potosí was a multiracial society, with native Andeans, Spanish settlers, and black slaves. The largest sector of the population were native men, forced to labor underground mining the silver ore, but there were considerable opportunities for merchants and native traders, who became wealthy. Suppliers of food as well as holders of urban and rural real estate prospered in Potosí. Women, particularly widows, held property, since they were guaranteed a portion of their husband's estate under Spanish law. Small-scale female vendors dominated street markets and stalls, selling food, coca leaves, and chicha (maize beer).
A portion of the female population were sex workers, who worked in brothels, many of which were annexed to gambling dens. The city of San Luis Potosí in Mexico was named after Potosí in Bolivia. In the United States, the name Potosi was optimistically given to lead-mining towns of Potosi, Wisconsin, and Potosi, Missouri, and also to the silver-mining town of Potosi, Nevada.