The rocks released by Coropuna are dark brown to black and porphyritic. They consist of andesite, dacite, rhyodacite, rhyolite, trachy-basaltic andesite, trachyandesite and trachydacite. The more recent lava flows have been dacitic or trachydacitic. Phenocryst phases include amphibole, biotite, plagioclase, pyroxene and titanomagnetite. Aside from the volcanic rocks, deposits of salts, sulfur and travertine produced by hot springs are found on the southern flank.