OH in naturally occurring corundum

A. Beran¹ and George R. Rossman

Division of Geological and Planetary Sciences

California Institute of Technology, Pasadena, USA 91125-2500

¹Permanent address: Institut für Mineralogie und Kristallographie, Universität Wien-Geozentrum, Austria

Abstract

            OH bands arising from intrinsic hydrous defects have been observed in the infrared spectra of a number of corundum crystals from worldwide localities.  The OH defects are most prominent in blue sapphire crystals suggesting an association of OH with oxidation/reduction reactions involving iron. The absolute concentrations are generally 0.5 ppm or lower; the linear OH absorption coefficient for the most intense band centered at 3310 cm^-1 never exceeds 0.005 cm^-1. In addition to the intrinsic OH defects, a number of previously identified hydrous inclusions often contribute to absorptions in the OH stretching  region of corundum.

Figure 1, 8.8 MB TIF file; small version 272 KB.

Figure 2, 14.0 MB TIF file; small version 379 KB.