  The hearts, kidneys, livers, spleens and brains of ${}^57$Fe enriched
wild-type and heterozygous $\beta$-thalassaemic mice at 1, 3, 6 and 9 months of
age were studied by means of M\"ossbauer Spectroscopy at 80K. Ferritin-like
iron depositions in the heart and the brain of the thalassaemic mice were found
to be slightly increased while significant amounts of Ferritin-like iron were
found in the kidneys, liver and spleen. The ferritin-like iron doublet, found
in the organs, could be further separated into two sub-doublets representing
the inner and surface structures of ferritin mineral core. Surface iron sites
were found to be predominant in the hearts and brains of all mice and in the
kidneys of the wild-type animals. Ferritin rich in inner iron sites was
predominant in the kidneys of the thalassaemic mice, as well as in the livers
and in the spleens. The inner-to-surface iron sites ratio was elevated in all
thalassaemic samples indicating that besides ferritin amount, the disease can
also affect ferritin mineral core structure.
