History: Serra Pelada Gold Mine, Pará, Brazil

Serra Pelada (English: "Bald Mountain") was a large gold mine in Brazil 430 kilometres (270 mi) south of the mouth of the Amazon River. The mine was made famous by the images taken by Sebastião Salgado showing an anthill of workers moving vast amounts of ore by hand. Because of the chaotic nature of the operation estimating the number of miners was difficult, but at least 100,000 people were thought to be present, making it one of the largest mines in the world. Today the Serra Pelada mine is abandoned and the giant open pit that was created by hand has filled with water, creating a small polluted lake.
Discovery
In January 1979 Farmer Genésio Ferreira da Silva hired a geologist to investigate whether gold he found on his property was part of a larger deposit. A local child swimming on the banks of a local river found a 6 grams (0.21 oz) nugget of gold. Soon word leaked out that indeed da Silva was sitting upon one of the largest deposits in the world. By the end of the week a gold rush had started with thousands of people descending on the farm to mine. Five weeks later, there were 10,000 on Ferreira's property and another 12,000 nearby. Huge nuggets were quickly discovered, the biggest weighing nearly 6.8 kilograms (15 lb), $108,000 at the 1980 market price. ($108,000US is now $ 300,926 in 2013)