Observations made on numerous grains of zircon from the heavy residues of soils from different areas indicate that zircon becomes corroded under certain conditions, particularly those of strong alkaline leaching associated with the development of a lateritic type of profile. Zircon crystals have a number of weak points, such as inclusions and zoning, which enable corrosion to set in; some of these are illustrated by photomicrographs. It is suggested, following information obtained from spring and ground-water chemical analyses, that Ca-bicarbonate and Na-bicarbonate rich waters may be able to dissolve zircon. Several experiments in the artificial weathering of zircon are described; one of these used a synthetic cation exchange resin. The results, obtained over a short period of time only, were negligible.