"Once you get down there, there's no air", describes one worker. "The rocks often bury us and you have to crawl through the tiny hole, using your fingers to dig." Labourers like him often go unpaid. They're forced to work at gunpoint by militias operating outside the control of the government. "Different armed groups do what they want with the population", laments minister Buta Muiso. But British businessman Ketankumar Kotecha sees nothing wrong in buying casiterite from the militias. "If I didn't do it, someone else would. I am not here as some kind of moral saviour."