The project is concerned with the rheology of on one of the most important key minerals of the earth's crust - quartz - for two reasons. 1) In polyphase rocks such as granites, i.e., in the presence of other minerals, quartz deforms by other deformation mechanisms than in monomineralic quartzitic rocks; a better understanding will enhance our interpretations of microstructures of polyphase rocks in the field. 2) Due to the immense experimental problems associated with the deformation of quartz, we still do not fully understand the operation of the basic slip systems of quartz. Better data will significantly improve our modeling of crustal rheology and our capacity for extrapolating from the lab to nature.