Quasicrystals can show a new type of localised defect termed a ‘phason’. At high temperature, these defects become mobile and lead to short-ranged atomic motion without involving vacancies. Cu in i-Al–Cu–Fe is involved in such phason jump process at high temperatures T on a time scale τ of ℏ/250 μeV. Surprisingly, τ Cu was found independent of the temperature, indicating a type of ‘assisted’ jump process. In order to investigate the iron dynamics in this system, we have studied i-Al 62 Cu 25.5 57 Fe 12.5 using quasielastic Mossbauer spectroscopy for T ≤1100 K. We find a temperature-dependent iron phason jump process with τ Fe typically two orders of magnitude slower than copper.