Cobalt is king in the digital world. It helps power the phone in your hand. Cobalt is also essential for electric cars. That increased demand is causing a "cobalt" rush in Africa. Tech companies are trying to avoid abuses, but it isn't easy. Marco Werman, host of PRI's The World, speaks with Vivienne Walt who just came back from the Democratic Republic of Congo to check out the cobalt craze. Click here to listen to the full episode.