FORTUNE -- Most of his neighbors are still sound asleep at 5 a.m., when Lukasa rises to begin his 12-hour workday. The slender 15-year-old, with an oval face and piercing stare, slips out of his family’s mud-brick home before dawn six days a week. Then he makes the two-hour walk from his tiny village in the southern region of the Democratic Republic of the Congo to a government-owned mining site. (Fortune is withholding the name of the village in order to protect Lukasa and other children.) Once at the mine, Lukasa spends eight hours hacking away in a hole to accumulate chunks of a mineral that is crucial to keeping our modern lives moving: cobalt.
By about 3 p.m., Lukasa has filled a sack with his day’s haul. He hoists the load, which can weigh up to 22 pounds, on his back and lugs it for an hour by foot to a trading depot. “I sell it to Chinese people,” he says, referring to the buyers from Chinese commodity trading companies who dominate the market in the area. Lukasa is wearing a T-shirt with “Prada” written on the front and sitting under a shade tree in his village on a recent Sunday, his one day off, as he explains his routine. With a hint of pride he says, “On good days I can earn 15,000 francs.” That adds up to about $9.