The eruption products of the 1600 eruption are dacites, which define a calc-alkaline, potassium-rich suite; the geochemistry of the 1600 rocks has also been described as adakitic. The 1600 rocks also contain rhyolite inclusions and a rhyolite matrix. Phenocrysts include biotite, chalcopyrite, hornblende, ilmenite, magnetite and plagioclase; amphibole, apatite and pyroxene have been reported as well. Aside from new volcanic rocks, Huaynaputina in 1600 also erupted material that is derived from rocks underlying the volcano, including sediments and older volcanic rocks, both of which were hydrothermally altered. Andesite has also been found at Huaynaputina. The Huaynaputina pumices have a white colour.