Four different mixtures of goethite, hematite and magnetite in different mass fraction percentage, were prepared.Raman and infrared spectroscopic measurements were carried out.For both sets of spectrum, mathematical relationships between the Raman and Infrared fraction, as obtained from the characteristic bands of each phase, and the respective mass fraction, were established.In most cases, linear relationships were obtained.A problem sample was used in order to estimate their respective relative phase abundances obtaining better results from the Raman spectroscopy measurements.