Hydrolytic Weakening in Quartz

In the hydrolytic glide regime, dislocation activity and the mechanism of water weakening depend on the water content of the quartz. High-quality synthetic quartz can be relatively dry ( 100 at. ppm [H[/[Si[), and in these samples the water is accommodated in the quartz lattice by point defects, speciflcally a (4H)si species (i.e., one Si is formally replaced by 4H [91].) Crystals with, say, 1000 at. ppm [H[/[Si[ contain aggregated molecular water in the form of bubbles. These can be fluid inclusions which have no long-range strain fields associated with them, or water 

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In quartz materials grown from seed crystals, the dominant impurity near the seed is molecular H2O. This gives way to OH— as you move away from the seed. It is the presence of such water molecules that is primarily responsible for the hydrolytic weakening in quartz. 

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