GEOC 154 |
| Jeffrey E. Post1, Peter J. Heaney2, and Christina Lopano2. (1) Department of Mineral Sciences, Smithsonian Institution, 10th Street and Constitution Avenue, NW, Washington, DC 20560-0119, (2) Department of Geosciences, Pennsylvania State University, 308 Deike Bldg, University Park, PA 16802 |
| Manganese oxide minerals with layer and tunnel structures occur in a wide variety of environmental settings, where they readily participate in cation-exchange, oxidation-reduction, and biologically mediated reactions. They have industrial applications as catalysts and octahedral molecular sieves. In order to better understand the role played by Mn oxides in natural systems, and their potential as materials, we are investigating their structures and behaviors using a variety of spectroscopic and diffraction methods. Synchrotron powder X-ray diffraction using an imaging plate permits time-resolved studies of structural changes during phase transformations and other reactions, e.g. dehydration reactions for birnessite and todorokite, in-situ cation exchange reactions for birnessite, and hydrothermal synthesis of todorokite from Mg-buserite. A single-crystal synchrotron diffraction study of woodruffite revealed a tunnel structure with triple and quadruple chains that has the largest tunnel of any known Mn oxide. |
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Microbially Mediated Manganese and Iron Oxidation in the Biosphere
1:45 PM-6:20 PM, Wednesday, March 31, 2004 Marriott -- Marquis NE, Oral
Division of Geochemistry |