In this paper we study the mineralogical characterization of the clay fraction of two samples of agricultural soils from Vertisols from the Valle de San Lorenzo, Piura Region, using analytical techniques such as energy dispersion X-ray fluorescence (XRF), X-ray difractometry (XRD) and transmission Mössbauer spectroscopy (TMS). Prior to their mineralogical characterization, the samples were subjected to physicochemical analysis such as measuring their pH, removal of organic matter and textural analysis. In this work we have used two samples, which have been referred to as M1 and M2 and drawn two different calicatas at a depth of 50 cm and 150 cm respectively. Mössbauer spectra were taken at room temperature. Analysis of both samples by XRF indicated that both samples have approximately the same concentration of Fe, which was approximately 3,5% and 3,9% for M1 and M2 respectively. It als...