Lava flow deposits are composed of andesite, basalt and dacite and lava domes consist of rhyolite. Plagioclase, apatite, magnetite and zirconia are the common mineral components of the rocks. The most common minerals in the ignimbrites are feldspar and clinopyroxene, while fayalite is rare. In addition to these minerals, the youngest rocks are andesites which contain amphibole. The area contains well-known Cu- and Mn-bearing resources in marine sediments that were deposited during the Pliocene. Zn and Co concentrations in the minerals surrounding La Reforma range from 242 to 38,847 and 22 to 17,407 ppm respectively. Some rocks of Pliocene were erupted in a submarine environment and have been converted into palagonite, which has a glassy structure.