gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1978.042.321.10 Pumpellyite-Bearing Basic Igneous Rocks from the Lower Ordovician of North Pembrokeshire, Wales Bevins R. E. Department of Geology, The University, Keele, Staffs. ST5 5BG 3 1978 42 321 81 83 22 6 1977 Copyright © 1978, The Mineralogical Society 1978 Summary

The first occurrence of pumpellyite in the Lower Ordovician volcanic rocks of North Pembrokeshire is reported and its form and chemistry are described. The significance of pumpellyite in relation to the grade of metamorphism attained during the Caledonian orogenic episode is discussed.