Rare earth mineral mining cost in China

These dust clouds are rising from deep craters in inner Mongolia, where the Earth's crust has been sliced away over decades. The rocks are pulverized to find valuable minerals known as rare earths. China has a tight grip on the world's supply of rare earth minerals. Here at the largest mine in the world, they've even fenced it off so that you cannot get any access. But not only is this causing trade tension with the United States, it's also coming at a huge environmental cost.

The radioactive waste has been drained into vast, man-made lakes, some of it seeping into the ground. Local villagers were moved after reports of cancer clusters and birth defects. In China's southern mining hub, the sites are smaller. Pools of toxic chemicals used to separate the metals dot nearly every hillside. The government is trying to mitigate the damage. [SPEAKING CHINESE]

But one local farmer accuses the mining company of causing landslides and grabbing land illegally. [SPEAKING CHINESE]

There is no ideal solution. Someone is always going to get hurt. Farmers like us, we are the vulnerable ones. It's pretty tragic. I really think it's tragic. We are being filmed. There are three of them coming to film us.

Our interview is interrupted. You've blocked the car in?

And men who claim to work for the mine block our car from leaving. [MEN SHOUTING] They also confront the farmer. Why do you need so many people here? It took three hours to talk them into letting us go. We asked the company for a statement, but it refused. China doesn't just mine rare earths. It processes 90% of the world's supply. Huge cities have grown up around the industry, employing tens of thousands. There are still some who make a small living from the land. [SPEAKING CHINESE]

There used to be Mongolian families living back there. The elders passed away, and the younger ones moved to the city to work. The rare earths companies bought our pastures, and we got paid.

Traces of this region's past still exist. The world relies on China's rare earth minerals, but the US and others are racing to secure their own supplies. Unless lessons are learned, no matter where they're mined, landscapes and lives will be put at risk. Laura Bicker, BBC News, Bayan Obo.