The rocks follow the calc-alkaline trend of magmatic differentiation, containing silicic lavas such as dacite. Their overall composition ranges from basaltic andesite to dacite, and the dominant lava rocks are andesite and basalt. Andesites range from green to gray in colour, and dacites are pink- and light-gray. The andesitic lavas contain phenocrysts of andesine, hornblende, plagioclase and hypersthene. Dacites have biotite, hornblende, plagioclase and quartz phenocrysts. Textures range from porphyritic to vitreophyritic. Andesites are more common in Pliocene rocks, and Pleistocene rocks tend to be dacitic. At least five cycles of andesite rock formation have been found on the southwest side of Koh-i-Sultan. Its rocks are typical volcanic-arc rocks in elemental chemistry, and may stem from mantle-derived magma. The satellite centre rocks differ from the main centre rocks in composition, suggesting that different processes generated the magmas which constructed the cones. There is a compositional trend from Bazman over Taftan to Sultan, with the latter having more potassium in its rocks than the other centres. Such compositional trends may come from different partial melting ratios and different fluid contributions to magma generation at each volcano.