We describe three sporadic layering events observed in mesospheric metal layers above Urbana, Illinois, using resonance fluorescence lidars and an ME radar. On June 6--7, 1991, a sporadic Na layer and a prominent temperature inversion layer were observed near 90 km. The formation of this low-altitude event appears to involve the release of Na from a chemical reservoir or from the srufaces of dust and smoke particles, perhaps facilitated by the high temperatures in the inversion layer. On December 10, 1991, sporadic Fe and Ca+ layers formed near 94 and 95 km, respectively, and on December 17--18, 1991, sporadic E, Fe, Na, and Ca+ layers formed simultaneously near 100 km. The characteristics of these December events suggest that sporadic Fe and high-altitude sporadic Na layers are formed by the neutralization of Fe+ and Na+ in the associated sporadic E layers. ¿ American Geophysical Union 1993