Mati Raudsepp

My research interests are focused on the detailed characterization of minerals and their synthetic equivalents, and the application of this knowledge to solve geological problems. As the composition and structure of synthesis products may be related quantitatively to natural growth conditions, we can predict the behaviour of systems not accessible to direct observation. To do this, I use Rietveld structure refinement, electron probe microanalysis, scanning electron microscopy, single-crystal structure refinement, and various complementary spectroscopic techniques to measure crystal-chemical properties. My laboratory work is firmly based on fieldwork, and I use the same experimental methods to study minerals in a wide variety of natural systems, particularly phosphates and oxides in granitic pegmatites and rare-element bearing minerals in general. In addition, as Director of the department`s microbeam and X-ray diffraction laboratories, I have a strong commitment to developing and applying microanalytical techniques to minerals. Current research projects research projects fall into the following areas.

The detailed characterization of bulk composition and cation order (structural state) in synthetic hydroxy-amphiboles, pyroxenes and complex phosphates using the Rietveld method. This work is complemented by single-crystal structure studies of appropriately coarse-grained synthetic and natural phases.

Developing rapid, accurate and precise methods for the modal and compositional analysis of minerals in rocks and solid wastes (e.g., mine tailings) using the Rietveld method and X-ray powder diffraction data. A single experiment can yield the mineral mode and the bulk composition and site occupancies of the constituent minerals. This work impacts significantly to the characterization of processes related to acid rock drainage in mine tailings, to the assessment of the effect of these processes on the environment, and to the better evaluation of certain kinds ore deposits.

The mineralogy of highly-fractionated granites and rare-element pegmatites. I am exploring the utility of the Rietveld method in characterizing complex phosphates and associated minerals. The aim of this work is to develop a more effective strategy for the characterization of complex mineral assemblages in general.