Catherine McCammon

The 2013 Robert Wilhelm Bunsen Medal is awarded to Catherine McCammon for her outstanding contributions to understanding the redox and spin state of iron in the Earth’s interior and the implications of this work for the evolution of our planet.

Catherine McCammon is awarded the Robert Wilhelm Bunsen Medal for her great achievements in mineralogical and geochemical studies on deep Earth materials, based on her innovative and highly original advances in Mössbauer, X-ray emission, and X-ray absorption spectroscopies.

Her studies, particularly those on oxidisation states and spin transitions of iron in high-pressure minerals, have produced new insights into the composition, constitution, and dynamics of subducted slabs and the Earth’s deep mantle. Her work has been instrumental in defining the oxidation state of iron in various regions of the deep interior, with profound implications for understanding and modelling core formation as well as the geochemical evolution of the planet. McCammon’s work with her collaborators in high pressure experimentation has shed light on many ‘big picture’ issues concerning the Earth’s deep interior: the history and cycling of oxygen in the planet, the oxidation state of the deep mantle, the effect of iron on mantle discontinuities, phase relations and seismic wave speeds, and the electrical conductivity of minerals. In addition, her work has clarified the effects of iron valence state on geothermometry and barometry of crustal and mantle rocks, and the valence changes of iron (and other multi-valent) species in melts. McCammon’s efforts have been critical to much of what we now know about the behaviour of iron, and to mineral physics in general, in the deep interior.

McCammon has been an innovator in the Moessbauer spectroscopic technique, largely devoted to investigating iron in all kinds of samples, from surface rocks, to small microscopic inclusions in diamonds. In particular, McCammon’s invention of the ‘Moessbauer milliprobe’ became critical to the study of iron valence and partitioning in many high-pressure experimental run products. She has applied the Mossbauer milliprobe to many other fields, including process metallurgy and the surface alteration of minerals.

In parallel with her efforts, McCammon has consistently contributed to the Earth science community through her editorial activities, and as councillor and now President of the AGU Volcanology, Geochemistry, and Petrology section.

McCammon constitutes a great example of a scientist ready to share her knowledge and expertise through collaboration with others, while having a strong and innovative research programme of her own.