Non-destructive crystal size determination in geological samples of archaeological use by means of infrared spectroscopy

► A new non-destructive methodology to determine crystal size has been developed. ► Infrared Spectroscopy has been demonstrated to be an alternative to X-ray Diffraction. ► The multivariate analysis provided good results in terms of accuracy and precision. ► The background of the relation between the IR spectra and crystal size was studied. ► The developed method was applied to geological samples of archeological interest.