MSA ROEBLING MEDALIST AWARD: REMINISCENCES OF A MINERALOGIST WHO WENT ASTRAY

During the 42 years since my undergraduate studies in chemistry and geology, the world has changed profoundly, particularly in areas of science and technology. My scientific career has benefited enormously from revolutions in computer technology, analytical instrumentation, and molecular theory, and the development of scientific user facilities such as synchrotron radiation sources. As a young mineralogical crystallographer working with Jerry Gibbs at Penn State and Virginia Tech, I collected intensity data on a “biologically automated” diffractometer on a 3 kW x-ray generator and spent hours doing electron microprobe analyses of minerals on a non-automated ARL microprobe. In my spare time, I dreamed about applications of MO theory to mineral structures as a means of explaining their relative stabilities. I also remember my excitement at being part of the development of “petrologic crystal chemistry” as a post-doc with Charlie Prewitt and Jim Papike at Stony Brook. Doing crystallographic work on intergrown pyroxenes from Apollo 12 basalts and helping to develop high-T x-ray single crystal methods and applying them to phase transitions in pyroxenes were scientific highlights of my time there. After a brief stay at Princeton, where I dabbled in primitive quantum chemical modeling of fragments of mineral structures, I moved to Stanford where I began to go astray from the mainstream of mineralogy. Having studied mineral structures almost to their melting points, it was a natural transition for me to melt them and study the structures of the melts and quenched melts using x-ray scattering methods. My next step was to begin studying structural environments of trace elements in silicate glasses/melts at SSRL using EXAFS spectroscopy. This led to a number of synchrotron-based studies of cation and anion environments in a variety of Earth materials (minerals, melts, glasses, aqueous solutions, mineral-water interfaces) and human calculi as well as mineral-microbe-heavy metal interactions and other molecular environmental science problems. I have also benefited enormously from working with 50 very bright grad students and postdocs as well as many collaborators, without whom I would not be here today. Given its key role in Earth sciences and many other interdisciplinary areas of science, mineralogy has a very bright future.