We studied two groups of samples called “La Calera” and “Amotape,” in situ from the Peruvian districts of Alto Laran and Amotape, respectively. Different techniques were needed to characterise them. By using X-ray diffractometry, we determined their phases as well as corroborated the cation exchange process in some samples; however, in other samples there was a large interplanar spacing. Through transmission Mössbauer spectroscopy, we obtained the valence state of iron. Consequently, we determined that the samples contained calcium and sodium clays. Additionally, we proceeded to optimise the calcium clays by cation exchange to obtain sodium clays, which can be used in wastewater treatment and other applications.