El Rojo Norte

18°28′S 69°12′W^[1] El Rojo Norte is a cinder cone in the Andes,^[2] constructed on top of volcano debris in the Lauca basin.^[1]

The cone is 150 metres (490 ft) high^[3] and 300 metres (980 ft) wide at its foot. Its profile has been reduced by erosion;^[1] the cone sits on an andesitic mound.^[4] A lava flow containing mafic andesite is associated with the cone.^[3] Phreatomagmatic deposits are also found.^[4]

The cone is formed by reddish scoria.^[1] Its rocks are basaltic andesite. It was erupted 3.1 ± 0.2 million years ago on the basis of potassium-argon dating.^[2] Other dates are 3.05 ± 0.22, 3.35 ± 0.16 and 2.34 ± 0.16 mya. Which age is correct is unclear, but the cone is partly buried by the 2.72 mya old Lauca-Pérez ignimbrite indicating that it's older than this ignimbrite.^[3]