Hydrous Components in Nominally Anhydrous Minerals

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9804871RossmanMany minerals which are nominally anhydrous actually contain low concentrations of water or hydroxide bound in distinct sites in their structure. These components influence the properties of the host phase toan extent that is far disproportionate to their actual concentrations, and together, constitute a globally significant reservoir of hydrogen in planet Earth. Our research program is directed at 1) characterizing the chemical form and concentrations of these components in natural minerals and related synthetic materials, 2) relating the hydrous components to other physical and chemical properties of the host phases, and 3) exploring the significance of the hydrous components to the terrestrial geologic system. We select naturally occurring minerals from a variety of geologic occurrences and characterize their hydrous components with infrared spectroscopy. A subset of our samples will then be prepared for Nuclear Profile Analysis which can determine the absolute hydrogen content. Working curves will be prepared for major groups of minerals found in both Earths crust and mantle. Synthetic minerals grown under controlled temperature and pressureconditions and with known chemical components will provide standards for examining the influence of chemical composition upon the hydrous components. They also will address the objective of relating information obtained from natural minerals to their conditions of formation.