HOW JIM THOMPSON TAUGHT GENERATIONS OF STUDENTS TO THINK OBJECTIVELY ABOUT ROCKS (AND LOTS OF OTHER IMPORTANT PROBLEMS) (Invited Presentation)

First things first: J.B.Thompson, jr. (1921 – 2011) respected his students. He taught his most profound insights no matter how undeserving our ineptitude. And he taught with integrity. Everything he said in class was backed up by pages and pages of faded pencil-scratchings on yellow legal pads.

Jim taught Willard Gibbs’ graphical analysis of phase equilibria so that petrologists could recognize equilibrium mineral assemblages at a glance. His exposition of Gibbs’ thermodynamics opened a new world of rigorous deductions on the conditions of origin of those beautiful turkey-track andalusites, kyanite-staurolite schists, and radiating sheaves of giant amphibole crystals.

Jim’s mineralogy was fun because he taught with transparently clear models: teaching single- and double-I-beam chains led to discoveries of triple-I-beam silicates (Jimthompsonite and Clino-jimthompsonite). His field mapping was inspirational: He projected three-dimensional structures of alpine tectonics onto two-dimensional outcrops of the forests of New England and made sense of those damned mossy ledges buried in pucker brush.

Jim opened the eyes of many to the internal beauties of reactions hidden inside crystals. Adularia-orthoclase-sanidine: same chemistry but different site distributions as increasing temperature disorders Al-Si distributions. Reminds this writer of the latest hot thing in stable isotope geochemistry: clumped isotopes. My, how Jim would have loved that!

I honor the memory of Jim Thompson whose impact was so profound on so many. His heritage lives on in the work of his students and of their students. Thank You Jim!