The sequence and ultimate pattern of mineralisation in the major lateral radula teeth of two species of limpet, namely Patelloida alticostata and Scutellastra laticostata (Mollusca:Patellogastropoda), have been elucidated using energy dispersive, Raman and infrared spectroscopies. In both species, iron is the first element infiltrated into the teeth and, in the form of goethite, occupies the posterior cutting surface of the tooth cusps, whereas silica mineralises the rest of the tooth. The first onset of mineralisation, as judged by the initial influx of iron, occurs in the junction zone, the region separating the tooth cusp from the tooth base. Although differences between the two species do exist, the general pattern of tooth mineralisation is very similar, suggesting that the mineralisation of iron and silica is a very ancient character, both in this group and among molluscs as a whole.