Bridget O'Neill, Jay D. Bass
Department of Geology
University of Illinois, 1301 W. Green St. Urbana, IL 61801, USA
George R. Rossman
Division of Geological and Planetary Sciences
California Institute of Technology, Pasadena, CA 91125, USA
Charles A. Geiger and Klaus Langer
Institut für Mineralogie und Kristallographie
Technische Universität Berlin, Ernst Reuter Platz 1
W-1000 Berlin 12, Federal Republic of Germany