Jose Bumba, left, pulls a 220-pound bag of cobalt from a 26-foot-deep hole in the makeshift mine in Kasulo, Congo, on April 26, 2021. (Ashley Gilbertson/The New York Times)

Jose Bumba, left, pulls a 220-pound bag of cobalt from a 26-foot-deep hole in the makeshift mine in Kasulo, Congo, on April 26, 2021. Working conditions on such sites can be extremely dangerous. (Ashley Gilbertson/The New York Times)