Cerro Rico, the mountain that eats men

Nobody agrees how many people died inside this mountain, and the disagreement runs into millions.

Cerro Rico, the Rich Mountain, stands in the Andes above the Bolivian city of Potosi. It was the richest source of silver in human history. Spanish extraction began in 1545, and from the 16th to the 18th century some 80 per cent of the world's silver came out of it, with around 85 per cent of all silver produced in the central Andes in that period coming from this one mountain. Potosi grew into one of the largest cities in the New World on the strength of it.

The labour was forced. The Spanish Empire used the repartimiento system, and in 1574 the Viceroy Francisco de Toledo reintroduced the mita, an annual forced-labour draft the Inca Empire had used before him. Mercury was central to refining the ore, and mercury poisoning among the Amerindian labourers was common and killed many of them. Conditions in the mines and on the refining patios killed more. The mountain's nickname comes from that.

The toll itself is genuinely disputed and it is worth being straight about it. A figure of around eight million dead is often repeated, but other sources put the number in the hundreds of thousands and argue that eight million was the death total for the whole Viceroyalty of Peru rather than for these mines. Historians including Peter Bakewell, Noble David Cook, Enrique Tandeter and Raquel Gil Montero have produced very different estimates, distinguishing free from unfree workers. Anyone quoting a single confident number is overreaching.

The danger has not ended. Around 15,000 miners still work here through cooperatives and at the open-pit San Bartolome mine. Constant dust means many contract silicosis, and life expectancy among them is roughly 40 years. Centuries of digging have hollowed the summit: a sinkhole opened at the top in 2011 and had to be filled with ultra-light cement, and the summit continues to sink a few centimetres a year.

UNESCO lists the City of Potosi, calling this the world's largest industrial complex of the 16th century, with its hydraulic mills, aqueducts, artificial lakes, the Casa de la Moneda, the Church of San Lorenzo and the barrios mitayos where the workers lived. In 2014 it was added to the List of World Heritage in Danger over uncontrolled mining. Visit Potosi and its mint. Tourist mine entries exist and they are genuinely hazardous.