From space, the gaping hole of the Grasberg open-pit mine sitting in the highlands of Indonesia's Papua province is unmistakable.

Here, in the world's largest gold mine and second-largest copper mine, 15 billion kg of copper and 1.5 million kg of gold have been unearthed from 1990 to last year, according to the website of United States mining giant Freeport-McMoRan, which operates the facility through its subsidiary, Freeport Indonesia.