This is the documentary from the BBC World Service.

I'm Robin Markwell in Chile, exploring the country's relationship with the red metal copper.

You're about to hear the story of a vast hole in the ground.

A hole so big you can see it from space.

A hole that was once a mountain.

I'm standing at the edge of an abyss.

I'm being very careful where my feet are right now

because were I to fall from here, I would

fall one kilometre. That is how deep this enormous crater is. It's the world's largest open pit mine.

It's called Chukikamata, and it's in the north of Chile in the Atacama Desert. The sun is beating

down here. There's a bright blue sky above.

And beneath where I'm standing, I can see white, wispy clouds. That's how huge this mine is.

Six kilometres long, more than three kilometres wide. And all around me, a whitish, greyish

rock, which has been blasted away for more than a century,

as humans have sought to find one thing. The precious red metal, copper. This is the

Copper Kingdom from the BBC World Service.

Well, we've come over to the refinery,

which is on the other side of the mountain

from where Chukikamata mine is.

And you'll be able to hear the activity in the yard here.

We've got forklift trucks going backwards and forwards,

and they have precious cargo,

...