2P X-RAY-ABSORPTION SPECTROSCOPY IN THE EARTH-SCIENCES

A complete knowledge of 3d transition-metal valencies, site occupancie s and sire symmetries is essential for a full understanding of mineral /melt energetics and behaviour. Over the last few years, significant a dvances in both instrumentation and theory associated with synchrotron radiation sources and experiments have enabled the development of 2p X-ray absorption spectroscopy as a sensitive, element-specific site an d valency probe. The potential of this technique in the Earth sciences is discussed in this paper with examples reflecting the variety of pr oblems set by 3d transition metals in natural systems.