BAILEY has inferred that Hamilton and Deans1 have agreed with Powell et al.2 that investigations of strontium isotopes show that the source of carbonatites is exclusively from below the sial. At present the isotopic composition of strontium has been examined in well-documented carbonatites and the results clearly show that they have been derived from a region that is identified by having a low 87Sr/86Sr ratio, similar to that found in basalts. The isotopic composition of strontium in carbonatites must be treated together with those from alkaline rocks in general. The 87Sr/86Sr for alkaline rocks has only been examined in a few cases while the isotopic composition of strontium in minor carbonate deposits, such as veins, pockets, breccia infillings, and that associated with ore mineralization have not been examined at all.