Abstract
Three models of the weakening of quartz by small amounts of water are described and analysed. Attention is confined to the glide of dislocations caused by a double-kink nucleation process. The structure of a double kink on a basal 60 degree dislocation is described and its formation energy estimated using a short-range interaction potential. The same potential was used to give a lower bound to its migration energy. The energies of Griggs-Blacic-Frank and (4H)//S//i models of water bound to kinks are also calculated. The results strongly support these models of hydrolytic weakening.