Potosí Silver Mine Opened

In 1545, Spanish colonists began working the silver deposits of Cerro Rico, the "Rich Hill" towering above the Andean highlands of present-day Bolivia. The mine at Potosí became the largest source of silver in the world for generations. It helped finance the Spanish Crown's wars and administration, reshaped global trade, and came at a terrible human cost for the Indigenous people compelled to work it.

Before the Spanish arrived, the region lay within the Inca sphere, and local people were already familiar with the mountain's mineral wealth. Spanish conquest of the Inca Empire in the 1530s opened the door to systematic exploitation. According to traditional accounts, the Spaniards learned of the deposit in 1545 with the help of an Indigenous guide, though the details of the discovery are told in several versions and cannot be confirmed. What is clear is that a settlement sprang up almost immediately at the foot of the mountain, at an altitude of more than 4,000 meters.

Output was modest at first, then surged after the 1570s. Two developments drove the change: the introduction of the mercury amalgamation process, which allowed lower-grade ore to be refined efficiently, and the viceroy Francisco de Toledo's reorganization of labor. Toledo expanded the mita, an adaptation of an Inca system of rotational labor service, requiring many Indigenous communities across the highlands to send a share of their men to work in the mines and refineries for set periods. Conditions were brutal. Miners faced collapses, toxic dust, mercury poisoning, and extreme cold, and many died or were permanently harmed. Enslaved Africans were also brought to the city, though the mita was the backbone of the labor system.

Potosí grew into one of the largest cities in the world by the early 1600s, with a population often estimated at well over 100,000, though figures vary among historians. Its wealth supported lavish churches, gambling houses, and a mint producing coins that circulated widely. Silver from Potosí and other American mines flowed to Spain, and from there to the rest of Europe, and a large share went across the Pacific to China, which demanded silver in payment for goods. This helped knit together what some historians describe as the first truly global economy.

For Spain, the windfall was both a blessing and a trap. It paid for armies and the imperial bureaucracy but also encouraged dependence on imported wealth and contributed to repeated financial crises. Output declined from the mid-1600s, though mining continued. The mountain, hollowed by centuries of tunneling, is still worked today by cooperative miners, and Potosí is a UNESCO World Heritage Site, a lasting reminder of the colonial wealth built on Indigenous labor.