7:30 PM
IN-PERSON
SILICA POLYMORPHS AND COLOR
Presented by George R. Rossman
Silica in the form of quartz is one of our most common minerals. In this presentation, we will first characterize the several different species of silica minerals other than quartz. These include such phases as cristobalite, moganite and melanophlogite. Then we will examine different colored varieties of the silica minerals including such favorites as rose quartz, amethyst, and opal. We will examine the chemical and microscopic features of the various colored varieties to see the origin of their colors that include both chemistry and natural radiation. We will briefly visit a few of the localities both near-by and around the world from which the colored varieties come as well as a factory where silica gems are synthesized. The tools of modern science now let us understand, often in atomic detail, how the colors of many of our favorite minerals came to be.
George R. Rossman is Professor of Mineralogy at the California Institute of Technology, Pasadena, California. He got his B.S. degree in Chemistry and Mathematics from Wisconsin State University, Eau Claire and his Ph.D. from Caltech in Chemistry. His principal research interests deal with the use of spectroscopic probes to study minerals. His work addresses problems relating to the origin of color in minerals. He uses a variety of spectroscopic methods for phase identification and to examine the role of metal ions in minerals and how they are affected by the long-term exposure to background levels of natural radiation. He has traveled to a variety of mineral localities around the world. He was the recipient of the inaugural Dana Medal, of the Mineralogical Society of America in 2001, the Richard P. Feynman Prize for Excellence in Teaching at the California Institute of Technology in 2004, and the 2021 Roebling Medal of the Mineralogical Society of America. He was also honored by having three new minerals of the tourmaline family named after him (pictured at left and right, Rossmanite).
The Veteran’s Memorial Multi-Purpose Room is in the back of the Veteran’s Memorial Auditorium Building. When entering the parking lot from Culver Blvd. (closest to Overland Blvd.), walk to the right when facing the building. Around the corner is a sign leading to the Multi-Purpose Room, where our meetings are held.
