Aconcagua Aconcagua Aconcagua (), with a summit elevation of , is the highest mountain in both the Southern and Western Hemispheres. It is located in the Andes mountain range, in the Mendoza Province, Argentina, and lies northwest of its capital, the city of Mendoza, about from San Juan Province and from the international border with Chile. The mountain itself lies entirely within Argentina, immediately east of Argentina's border with Chile. Its nearest higher neighbor is Tirich Mir in the Hindu Kush, away. It is one of the Seven Summits. Aconcagua is bounded by the "Valle de las Vacas" to the north
Ojos del Salado of fumaroles high on the mountain and recent-looking lava flows, albeit of uncertain age, also argues in favor of a categorization as "active." By these definitions, Ojos del Salado is the highest historically active volcano on Earth. If the older date is accepted, the title of "highest historically active volcano" might reside instead with the somewhat lower Llullaillaco volcano, which certainly has erupted in historic times (most recently in 1877) and is considered active. Salado's rock is predominantly potassium-rich dacite and rhyodacite. Its lavas are high in biotite, hornblende, plagioclase, and opaques, with lower levels of augite, quartz, and hypersthene.