Rio Tinto, a big mining company, has apologized for losing a small radioactive capsule while moving it across Western Australia. An emergency search is happening along the 1,400km (870 miles) route for the device, which is about the size of a pea. The capsule has a small amount of Caesium-137, which is radioactive and could make people very sick if they touch it. This could mean skin damage, burns, or radiation sickness...Learn more