The world's largest open-pit copper mine has consumed an entire town. The pit is visible from space and descends nearly 1km. Operations now continue underground.
Diego Delso, CC BY-SA 4.0, via Wikimedia Commons
A century-old chasm
The Chuquicamata open-pit mine, often called "Chuqui," is a massive excavation in the Atacama Desert. The main pit is approximately 4.3 kilometers long, 3 kilometers wide, and has reached a depth of over 900 meters, making it one of the deepest open-pit mines in the world. Industrial-scale operations began here in 1915, and for over a century, the mine expanded, hollowing out a vast quantity of rock to become the largest open-pit mine by excavated volume.
The geology of Chuquicamata is that of a classic porphyry copper deposit, formed by hydrothermal fluids that circulated through igneous rocks millions of years ago during the Eocene-Oligocene epochs. This process concentrated copper and other minerals, including molybdenum, in a complex of intrusive rocks known as the Chuqui Porphyry Complex. The orebody contains minerals like chalcopyrite, bornite, and chalcocite. A major geological feature, the West Fault, separates the mineral-rich eastern side of the pit from the barren western side.
The underground evolution
For decades, the mining camp and later town of Chuquicamata existed beside the growing pit. It once housed a community of 25,000 people. The relentless expansion of the mine, along with environmental concerns over dust and smelter gases, made the town's location unsafe. Between 2004 and 2007, the entire population was relocated to the nearby city of Calama, and Chuquicamata is a ghost town, slowly being consumed by piles of waste rock.
By the late 2010s, the open-pit operation was becoming less profitable. To access the vast reserves located deep beneath the pit floor—estimated at 1.7 billion tons of ore—a monumental shift in strategy was required. In 2019, Chuquicamata officially began its transformation into a large-scale underground mine. This multi-billion dollar project uses a block caving method, where large sections of ore are undercut and allowed to collapse under their own weight. The new underground infrastructure includes a 7.5-kilometer main access tunnel and multiple ventilation shafts, extending the mine's life for at least another 40 years.
💡Fun Facts
The name "Chuquicamata" is believed to come from the Aymara language and refers to the local Chuco indigenous people.
A mummified man, believed to have been a miner, was discovered in an ancient shaft in 1899 and dated to approximately 550 C.E.
Before its nationalization in the 1970s, the mine was operated by the U.S.-based Anaconda Copper Mining Company.
To extract 1 kilogram of copper from the mine, workers must remove and process around 100 kilograms of rock.
The state-owned operator, Codelco, has historically offered free guided tours on weekdays. Reservations must be made well in advance by email. Tours are subject to cancellation based on operational needs.
Admission
Free, but a donation to a local children's charity is often requested.
Accessibility
Tours are conducted by bus. The terrain is industrial and rugged. Visitors must wear long pants and closed-toe shoes.
