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Visitors to the Athenaeum basement’s 
Professor of Mineralogy, Emeritus, George Rossman (1944–2026), whose history of having “no formal training whatsoever in geology” never stood in the way of his becoming an internationally renowned authority in the field of mineralogy, talks about his life and career in a four-part interview series.
Born and raised in Eau Claire, Wisconsin, Rossman was still in grade school when his early fascination with the rainbow array of colors he found in rocks and minerals developed into a more mature understanding that “the rocks I was picking up were part of chemistry.” He experimented with explosives and corrosives as well as less hazardous substances at home in a makeshift laboratory, won prizes in science competitions, and earned his BS degree in chemistry and math at Wisconsin State University, where his professors encouraged him to pursue graduate study at a place “I’d never heard of” in Pasadena, California. At Caltech, where he did thesis work in inorganic chemistry, his self-taught expertise in rock and mineral science caught the eye of the Institute’s geologists, from whom he often borrowed samples for his research. His advisor Harry Gray put him in charge of his instrumentation lab and made him his TA in a gonzo reinvention of Caltech’s introductory chemistry course that combined boisterous, high-powered instruction with showstopping demonstrations of chemical reactions. Rossman soon gained a reputation as a dynamic, inspiring teacher. He turned down multiple job offers to accept a temporary position as a Caltech instructor in mineralogy because “it sounded like fun”—a trial run that evolved into more than fifty years on the professorial faculty.
Throughout his research career Rossman returned to the question that had intrigued him since childhood—what accounts for the diversity of color in gems and minerals. He drew on his training in chemistry, introducing optical and infrared spectroscopy to address these and other problems that mineralogy’s traditional reliance on crystallography “was unable to answer easily or satisfactorily.” He describes how these techniques enabled him and his students to conduct atomic-level investigations of how naturally occurring phenomena such as trace elements, radiation, and temperature changes bestow color on tourmaline, sapphire, topaz, diamond, and rose quartz, among others, and how reproducing these conditions artificially has gained traction in the gem industry. His spectroscopic methods also enabled the detection of hydrogen and water in minerals long assumed to be “dry”—a finding with significant implications for understanding hidden reservoirs of water deep within the earth—and extended to studies of lunar materials and Martian meteorites. He discusses collaborations with Caltech colleagues, gemologists, and, above all, decades of students, whose contributions he singles out for special credit.
Other topics include his role as curator of Caltech’s gem and mineral collection, his interactions with beleaguered Ukrainian scientists, and a detective-like foray into the somewhat dubious origins of the official “rare gem” of the 2008 Summer Olympics. Field expeditions near and far, from Pala, California—a rich source of Rossman’s favorite gem, tourmaline—to gold and ametrine deposits along the Amazon, to the remote jade and ruby mines of Myanmar—add a touch of Raiders of the Lost Ark adventure to this retrospective.