Distinguished for his work on the distribution of trace elements and their behaviour in geological processes. He has contributed greatly to the development of spectrographic methods of analysis and pioneered the use of spark source mass spectrography on geological materials. He developed methods using the variations in the ratios of elements entering the same lattice sites to provide genetic information about crystallization processes in igneous rocks. This has had important application to the study of andesitic volcanic rocks in orogenic regions and suggests that they are derived from the mantle and not the crust as previously supposed. He has made extensive studies of tektites and meteorite impact glasses and identified the source material of Henbury and Darwin glass. He has throughout been a strong supporter of the terrestrial origin of tektites and indicated a sandstone-like material as likely parent for the Australites. Recently, he has been involved in the preliminary analysis of the lunar samples at the lunar receiving laboratory, Houston.