gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1960.032.251.02 The Amygdale Minerals in the Tertiary Lavas of Ireland. IV. The Crystal Habit of Calcite Walker G. P. L M.Sc., Ph.D., F.G.S. Dept. of Geology, Imperial College, London S.W. 7 12 1960 32 251 609 618 Copyright © 1960, The Mineralogical Society 1960 Summary

Calcite is widespread in amygdales associated with the zeolites; the characteristic forms being {022¯1} and a steep scalenohedron in the zone [1¯101], usually {13.11.24¯.2}. Crystals from one locality have faces of {16.1.17¯.0}, a form new to calcite.