Taftan has erupted lavas ranging from basaltic andesite to dacite. The dominant rock is andesite, with SiO2 content ranging from 49.8 to 63.5%. Grey andesites form the youngest rocks on the main summit and contain chlorite schist and biotite gneiss inclusions. The andesites are vesicular. The magma of Taftan volcano is very oxidized, as can be inferred from the composition of the surrounding ignimbrite and fumarole gases.