Emi Koussi is a high pyroclastic shield volcano that lies at the southeast end of the Tibesti Mountains in the central Sahara, in the northern Borkou Region of northern Chad. The highest mountain of the Sahara, the volcano is one of several in the Tibesti range, and reaches an elevation of 3,415 metres, rising 3 km above the surrounding sandstone plains. The volcano is 60–70 kilometres wide and has a volume of 2,500 cubic kilometres.