A. M. Clark, E. E. Fejer, A. G. Couper, O. von Knorring, R. W. Turner and R. W. Barstow
Dept. of Mineralogy, British Museum (Natural History), Cromwell Road, London SW7 5BD
Formerly, Dept. of Earth Sciences, University of Leeds, Leeds LS2 9JT
Drakewalls, Gunnislake, Cornwall PL18 9EG