gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1962.033.257.07 Quartz after Tridymite in an Acid Intrusion from Mull Skelhorn R. R. B.Sc., Ph.D., F.G.S. 1 King's College, London, W.C. 2.

Present address: Sir John Cass College, London, E.C. 3.

 6 1962 33 257 138 144 Copyright © 1962, The Mineralogical Society 1962 Summary

The occurrence of tridymite, now inverted to quartz, in a craignurite (allied to granophyre) from Craignure, Mull, is described. An account of the field occurrence and petrology and a new analysis of the craignurite are given. The significance of the occurrence of tridymite is discussed in the light of recent experimental studies.