Dartmouth's Robert Reynolds wins the Roebling Medal for lifelong achievement in mineralogy

Posted 01/19/01

While still in high school, Dartmouth Professor Robert C. Reynolds Jr. persuaded his principal to help him order chemicals and glassware for a makeshift chemistry lab he was constructing in a spare bedroom of his home. Thus began the lifelong devotion to science that recently earned Reynolds the Roebling Medal, the highest honor given in the world of mineral research.

Reynolds, the Frederick Hall Professor of Mineralogy Emeritus in the Earth Sciences Department, was awarded the medal at the Mineralogical Society of America (MSA) annual meeting this fall. The society gives the honor to scholars--typically mineralogists, although not necessarily--whose research makes an outstanding contribution to mineralogical science. Past honorees include Nobel Prize winners William Lawrence Bragg and Linus Pauling, as well as Dartmouth alumnus James B. Thompson '42 who received the award in 1978.

"In examining a list of previous awardees, I am truly humbled to see my name on a list that includes the giants of my field, many of whom I regard as heros," said Reynolds.

Reynolds, who joined the Dartmouth faculty in 1960, is an expert on the family of clay minerals that is the most common mineral group on the earth's surface. They are the major constituent of the world's best soils, and of sediments beneath the sea. These minerals have unique properties that are instrumental for supplying plants all their nutrient elements, and they also are involved in the conversion of organic matter to petroleum and natural gas resources when sediments become deeply buried, said James Aronson, Professor of Earth Sciences. "The most important application of Dr. Reynolds modeling has been understanding the detailed mineralogy and transformations of this important family of clay minerals," said Aronson. "He more than anyone else has produced a way of understanding these minerals."

Because these minerals are so tiny and cannot be seen and tested by hand, they are principally studied and identified by beaming X-rays off them and looking at the pattern of the diffracted rays that have interacted with the atoms of the mineral. Clay minerals have a layered structure of their atoms, and because of their tiny size this arrangement can be quite complex. Often the structures of two or more clay minerals are interlayered.

"Bob's contribution has been to provide dynamic reliable computerized mathematical models of the X-ray scattering patterns of almost all conceivable clay minerals," Aronson said. Today scientists throughout academia and industry are able to identify every nuance of their particular clay mineral by matching their observed X-ray patterns dynamically to those they can generate using Reynold's computer models. Doing so, they, for example, can evaluate if a prospective sedimentary basin has proceeded along its geologic path of temperature and time sufficiently enough to have generated petroleum, said Aronson. Reynolds' foundation paper on the subject, published in 1970 with J. Hower, is perhaps the most cited paper in all of clay mineralogy, he added.

Reynolds' contributions to mineralogy include inspiring other young scientists to enter the field, said Richard Birnie, Professor and Chair of the Earth Sciences Department.

"In addition to being a superlative scholar, Bob is also an outstanding teacher and has been an inspiration to many students. I am one of many who can give testimony to this," Birnie said, noting that he first took a class from Reynolds 35 years ago while he was a student at Dartmouth.

"Bob's students are scattered throughout industry, academia and government service, and I know he's very proud of the students whom he introduced to geology," he added.

In addition to the 2-inch 14-carat gold engraved medal that Reynolds received, a symposium on mixed-layer clays was held at the conference in his honor. Several of Reynolds' former students participated in this session as presenters. He also will receive a duplicate medal in bronze and will become a lifetime fellow of MSA.

First awarded in 1937, the Roebling Medal is named for Washington Roebling, an engineer and mineral enthusiast who was responsible for completing the design and construction of the Brooklyn Bridge.