Laguna del Maule has erupted andesite, basaltic andesite, basalt, dacite, rhyodacite and rhyolite, the andesites and basaltic andesites define a rock suite with medium potassium contents~. In the Loma de Los Espejos rocks a SiO2 content of 75.6-76.7% per weight has been noted. After deglaciation, the composition of Laguna del Maule volcanic rocks has grown more silicic, with andesite eruptions being limited to the edges of the volcanic field since 19,000years ago. Generally, the postglacial phase of activity has generated about of rhyolite and of rhyodacite. Of the more than of volcanic rock in the Laguna del Maule field, about were emplaced postglacially.