Mining of tin, copper and some rarer metals was one of the county's principal industries until well into the 20th century, but it no longer exists—the last working tin mine in Europe, South Crofty, near Camborne, finally closed in 1998, but in November 2007 it was announced that the mine may restart production in 2009, though as of 2015 this had not yet occurred. Several defunct mines applied for status as UNESCO World Heritage Sites. However, the Camborne School of Mines is still a world centre of excellence in its field.