⁵⁷Fe Mössbauer spectra of two Pueblo pottery clays were obtained at high temperatures during the process of firing and for clay samples which had been fired and cooled. The regular behavior of the major Mössbauer quadruple doublet offers promise for its use as a thermometer to measure temperatures at which ancient ceramics were fired. Changes in the magnetic sextuplet and secondary doublets are sensitive to individual differences between the clays and to differences in the behavior of the iron-bearing minerals in the clays at high temperature and after the clays have been cooled.