Ikuo Kushiro was awarded the Harry H. Hess Medal at the AGU Spring Meeting Honors Ceremony, which was held on June 2, 1999, in Boston, Massachusetts. The medal recognizes outstanding achievements in the research of the constitution and evolution of Earth and its sister planets.

Characterization of rock-forming processes requires laboratory experiments to determine the physicochemical properties of materials or their analog model compounds at high temperatures and high pressures. The experimental data, however, are not particularly useful unless integrated with observational and theoretical information. Ikuo Kushiro, this year's winner of the Harry H. Hess Medal, approaches experiments with this integrated view as his guiding light. He does experimental petrology, geochemistry and geophysics, but always with the understanding that the experimental data provide only a piece of a more complex puzzle. It is perhaps in part because of this attitude that Ikuo and his colleagues have provided the fundamental experimental data on phase equilibria, element partitioning, and equation-of-state of molten silicate applicable to most major rock-forming processes in the Earth. All too often we ask what we can do with our instrumentation and proceed from there. Ikuo first asks the real question and then designs the experiment.