Argyle diamond mine at the Ekati mine, both in Canada. However, Argyle has two to four times the concentration of diamonds (ore grade) of these mines. This makes extraction economically feasible, as mine costs are mostly related to the amount of ore processed, not the amount of diamond extracted. In 2005, Rio Tinto was given the go-ahead to a future expansion project, moving it from an open pit to an underground mine. This plan was postponed; in September 2010 Rio Tinto announced fresh plans to develop an underground mine beneath the existing pit, increasing annual production to 9 million tonnes of ore. The
Historic Silver Mine in Tarnowskie Góry Adit, part of the Deep Adit Fryderyk, was the first to be exploited for tourism. In 1957, it was opened as a 600 metre long boat tour. The Historic silver mine opened in 1976. The visit in Historic Silver Mines starts in a interactive museum where tourists get the knowledge of methods of silver, lead and zinc ore extraction as well as underground mine drainage. Then tourists go underground. The trail is 1,749 meters long; 270 meters are travelled by boats. Outside the buildings of Historic Silver Mine there is an Open Air Steam Engine Museum. The new attraction of