Irruputuncu's rocks consist of andesite- and dacite-containing hornblende and pyroxene. The El Pozo ignimbrite is pumice-rich and has a composition between trachyandesite and trachydacite. Minerals amphibole, biotite, hornblende, quartz and plagioclase comprise the rocks. The Irruputuncu I lava flows are composed of trachyandesitic with biotite and plagioclase, while the Queñoas are composed of andesite and trachyandesite. The block and ash flows and Crater lavas consist of solely trachyandesitic rocks. Overall, these rocks belong to the potassium-rich calc-alkaline series typical of CVZ volcanoes. The magmas are formed by plagioclase and clinopyroxene crystallization with some mixing. Irruputuncu's rocks show minor evidence of crustal contamination, similar to other CVZ volcanoes located within transition zones.