How the world depends on small cobalt miners

the dust-caked men carrying sacks of rocks into a trading depot outside Kolwezi, in the south-east of the Democratic Republic of Congo (), have little in common with the housewives in rich countries who hold parties to sell Avon creams. But in both cases, the more you flog, the better the bonuses. At the depot, under a ramshackle roof, handwritten posters state prices for the minerals in the ore. Industrious miners who hit production targets get bumper perks such as a bag of maize meal, a smartphone or television. The ultimate prize is the cobalt that will be extracted from the rock. For decades unloved, cobalt is now at the heart of the green economy. It is an essential component of batteries in phones, laptops and , which are now the biggest source of demand. The authors of an paper published last year predicted that consumption of cobalt could increase six-fold by 2050 as the world tries to curb global warming. However, they also note that cobalt supply could be .