On Tuesday, Ghana announced that foreigners will be kicked out of the country’s gold trade as of next month. Gold is Ghana’s top export and the country is No. 6 in the world for the prized metal’s output. But as researcher Gavin Hilson tells The World’s Marco Werman, illicit mining and smuggling operations are pervasive in the country. Hilson studies the environmental and social impacts of the small-scale mining sector in West Africa. He’s a professor at the University of Surrey in the UK.