The Grasberg Mine is a vast open pit mine in Papua, Indonesia, forming a crater an entire mile wide. For years it has been one of the most productive mines in the world, with massive reserves of gold and copper. Situated high in the rugged Sudirman Mountains near two rare equatorial mountain glaciers, it is also the world’s highest quarry, some 14,000 feet above sea level. 

This massive mine sits at the collision point of two tectonic plates, where millions of years ago hot magma intruded into sedimentary rock layers during the uplift of the local mountains, resulting in the formation of copper- and gold-bearing ore. Since the early 1990s, the Grasberg operation has been busily extracting this ore at a staggering volume. In 2016, the vast mine produced more than 1 billion pounds of copper and 1 million ounces of gold.

Once the precious metal is extracted, it is crushed in the mine’s milling and concentrating complex, which is the largest in the world. The grinding units at the mill can process a daily average of 265,000 tons of ore. The ore is then sent in a slurry along three pipelines to the seaport of Amamapare, over 70 miles away. It is filtered and dried at the port, after which the copper, gold, and silver can be shipped to smelters around the world.

Today, the pit mine has been all but exhausted. But while production has temporarily fallen away, the huge reserves of gold and copper remain—albeit deeper underground. Grasberg is now transitioning to underground block carving, with underground mines replacing the work in the pit.

Unsurprisingly, such a massive mining project has not gone without its share of controversy. To start are the environmental concerns: Each year, the mine dumps tens of millions of tons of waste into the local river system, which is now almost devoid of fish and generally considered unsuitable for aquatic life. Freeport-McMoRan, the U.S. company in charge of the mine, has long insisted that its practices meet industry standards. That, however, is not a position held by environmental groups and local citizens. Tensions have also flared at Grasberg due to the low share of revenue going to local Papuans, and questionable payments made by the mine to the Indonesian security forces that protect it.