| Description | Correspondence between Dr Paul Henderson, NHM and Dr Fred A Frey, Associate Editor of Geochemica et Cosmochimica Acta, Department of Earth and Planetary Sciences, Massachusets Institute of Technology and correspondence between Dr Robert Hutchinson, NHM and J D Macdougall, Associate Editor of Geochemica et Cosmochimica Acta, Department of Earth and Planetary Sciences, Massachusets Institute of Technology |