Nevado Sajama is an extinct stratovolcano

Stratovolcano

A stratovolcano, also known as a composite volcano, is a tall, conical volcano built up by many layers of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile and periodic, explosive eruptions...

 and the highest peak in Bolivia

Bolivia

Bolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...

. The mountain is located in the Oruro Department

Oruro Department

Oruro is a department in Bolivia, with an area of 53,588 km². Its capital is the city of Oruro. At the time of census 2001 it had a population of 391,870.- Provinces of Oruro :...

, Sajama Province

Sajama Province

Sajama is a province in the northwestern parts of the Bolivian department of Oruro.-Location:Sajama province is one of the sixteen provinces in the Oruro Department...

, Curahuara de Carangas Municipality, Sajama Canton. It is situated in the Sajama National Park

Sajama National Park

Sajama National Park is a national park located in the Oruro Department, Bolivia. It borders Lauca National Park in Chile.The park lies within the Central Andean dry puna ecoregion.. It features a spectacular Andean landscape, with elevations ranging from . It contains the snowy cone of Nevado...

 in the southwest area of the country some 16–24 km (10-15 mi) from the border with Chile

Chile

Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

. The peak is an isolated cone, but is geologically complex, with lava dome

Lava dome

|250px|thumb|right|Image of the [[rhyolitic]] lava dome of [[Chaitén Volcano]] during its 2008–2009 eruption.In volcanology, a lava dome is a roughly circular mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano...

s of andesitic

Andesite

Andesite is an extrusive igneous, volcanic rock, of intermediate composition, with aphanitic to porphyritic texture. In a general sense, it is the intermediate type between basalt and dacite. The mineral assemblage is typically dominated by plagioclase plus pyroxene and/or hornblende. Magnetite,...

 and rhyodactic composition overlain by an andesitic stratovolcano.