We are indebted to Ben Kreulen, Prof. Touret and Steve Cox for supplying sample material from Naxos, Scandinavia and Victoria respectively, and Steve Cox for help with collecting quartz samples. This work was sponsored by a NWO Huygens fellowship to JLU. Harry Green and the late Tracy Tingle are thanked for introducing JLU to using the Griggs rig. G. Kastelijn and E. de Graaf are gratefully acknowledged for technical assistance. ADP likes to thank P. Fokker for useful and stimulating discussions and for supplying a workspace. We are grateful to J. Severstone and H. Stünitz for thorough and constructive reviews. In particular we would like to acknowldge John Fitz Gerald for his review and editorial help.