 The complex was active from the late Pliocene, around 2.7 Ma, until the earliest Pleistocene, around 2.3 Ma.The complex at Iza consists of two domes; Domo Holcim with and Domo Los Sauces in size.They consist of porphyritic rhyolites with sanidine and plagioclase as dominant mineral groups and abundant xenoliths of sedimentary rock and in minor quantities volcanic or metamorphic fragments.