John Eiler is a geologist and geochemist specializing in the distribution of the stable isotopes among natural materials. His research group is best known for developing the study of natural molecules containing two or more rare isotopes — a rare but ubiquitous family of species that give rise to a variety of applied geochemical tools. He is a recipient of the Day medal, Epstein medal, Macelwane medal, and Mineralogical Society of America young scientist award, and a member of the National Academy of Sciences.