George R. Rossman
Division of Geological and Planetary Sciences,
California Institute of Technology
Pasadena, CA 91125-2500 U.S.A.
Hydrous components in nominally anhydrous
minerals have been the object of increasing study for the past
three decades. OH ions and, less commonly, H2O molecules are
found in many anhydrous minerals at concentrat ions ranging from
ppms to tenth's of a percent by weight. Infrared spectroscopy
remains the preferred method to characterize these components
because of its sensitivity to chemical species, crystallographic
orientation and analytical concentration. Improved calibration of
the infrared measurements provides a quantitative understanding
of the importance of the global hydrogen reservoir contained in
the ''anhydrous" phaises. New and revised values for the
amount of H2O in anhydrous minerals are summarized.