Gold, Obuasi & Tarkwa (Ghana)

Africa's leading gold producer since overtaking South Africa, Ghana draws more than half of its foreign currency from the yellow metal. But illegal artisanal mining (galamsey) escapes the state, poisons most of the country's watercourses with mercury and cyanide, and feeds a smuggling estimated in the billions. A vital revenue stream and an environmental catastrophe are extracted from the same subsoil.