The edifice is mainly constructed by lava flows that bury parts of the calderas in the foot of the volcano. Palomo has erupted andesite and dacite, as well as basaltic andesite. All rocks are calc-alkaline rocks of medium potassium content. The main edifice rocks contain abundant phenocrysts dominated by plagioclase; clinopyroxene, orthopyroxene and other minerals are less prevalent. The Andrés edifice has a distinct composition, with more amphibole and olivine and less plagioclase than the main edifice.