This project represents a continuation of research previously supported by NSF grant EAR 85-07925, involving studies of the structure and atomic motions in molten and glassy silicates using nuclear magnetic resonance (NMR) spectroscopy. A previously developed high-temperature NMR probe and furnace system will be used to continue studies of NMR lineshapes and relaxation times of Si-29 and Na-23 in alkali silicate and aluminosilicate melts, extending the studies to include wider composition and temperature ranges. In addition, O-17 measurements will be initiated, and the resulting observations of atomic-scale processes will be related to known thermodynamic properties of the melts. Work will also be continued on glasses and the glass transition, emphasizing the effects of quench rate (and therefore transition temperature) on structure and defects. Finally, the clustering of protonated species in hydrous glasses will be studied using multiple quantum 1-H NMR techniques. The results of these studies will improve our understanding of the fundamental thermodynamic and transport properties of important silicate melts and glasses.