Monte Pissis is an extinct volcano on the border of the La Rioja and Catamarca provinces in Argentina, 25 km (16 mi) to the east of the Chilean border and about 550 km (340 mi) north of Aconcagua. The mountain is the third-highest in the Western Hemisphere. Monte Pissis is named after Pedro José Amadeo Pissis, a French geologist who worked for the Chilean government. Due to its location in the Atacama Desert, the mountain has very dry conditions but features an extensive glacier, with crevasses, which is unique in the region.