has been a big industry for centuries, with some of the world's richest deposits found deep underground.

rely on mining to drive their , and demand for the precious metal remains high across the world.

Some mines produce only a small amount of gold each year, but others extract thousands of tonnes over their lifetimes.

No gold mine, however, is as productive or valuable as the one in a remote mountain region of .

The Grasberg mine, located in Papua, Indonesia, is , producing around 48 tonnes of gold every year.

It is also one of the biggest copper mines globally, with the ore extracted from Grasberg containing high grades of both metals.

To keep up with demand, the mine operates on a scale unlike any other, with a workforce of around 20,000 people and its own airport, seaport, roads, housing, schools, and a hospital.

is owned by PT Freeport Indonesia, a joint venture between the Indonesian government and American mining giant Freeport-McMoRan.

The facility is located near Puncak Jaya, the highest mountain in Papua, in an area rich in mineral deposits formed by shifting tectonic plates.

For decades, the mine's most distinctive feature was its mile-wide open pit, but surface deposits have now been largely depleted, shifting production underground.

Grasberg now operates three major underground mines, known as Grasberg Block Cave, Deep Mill Level Zone, and Big Gossan.

In 2023, Grasberg produced 52.9 tonnes of gold (1.7 million ounces), 680,000 tonnes of copper, and 190 tonnes of silver, making it one of the world's most profitable mining operations.

The mine still holds gold reserves worth an estimated $40 billion (£31 billion), ensuring that it will remain a major producer for years to come.

Grasberg's huge scale means it requires major infrastructure to function. The mine has a dedicated airport to transport workers and equipment in and out of the remote site, as well as a 103-mile pipeline that carries ore to the Amamapare port for processing and export.

To support the workforce, Grasberg also has its own schools, employee housing, and medical facilities.

The mine's history dates back to 1936, when Dutch geologist Jean Jacques Dozy discovered mineral-rich rocks in the region.

However, large-scale mining didn't begin until the 1960s, when Freeport-McMoRan secured the rights to develop the site.

Since then, Grasberg has seen continuous expansion, with billions invested in new tunnels, roads, and transport systems.

Despite its economic importance, Grasberg has also faced controversy. Environmental concerns have been raised over high levels of sediment and heavy metals entering local rivers, while political tensions in the region have led to security issues and attacks on the mine by separatist groups.

There have also been worker strikes and disputes over pay and conditions.

Despite these challenges, the mine remains one of Indonesia's most valuable assets, and the government has extended Freeport-McMoRan's mining lease until 2041