A team of researchers in Russia - including scientists at St. Petersburg State University, the Institute of Volcanology at the Russian Academy of Sciences, and the firm Mechanobr-Analit in St. Petersburg – has analyzed the properties and structure of a new mineral christened “prewittite” after the Geophysical Laboratory’s illustrious former director, Charles T. Prewitt. Their findings were reported in a recent paper published in the journal American Mineralogist (Volume 98, pages 463-469, 2013) found here.

Prewittite, or KPb1.5Cu6Zn[SeO3]2O2Cl10, was discovered in 1983 in the fumarole fields of the Great fissure Tolbachik eruption that occurred in 1975-76, Kamchatka peninsula, Russia. Named after Charles T. Prewitt for his groundbreaking contributions to the field of mineral sciences in particular the crystal chemistry of minerals and planetary materials, it is yet another fascinating example of a complex copper selenite chloride found in the region. The chemical composition and single crystal and powder X-ray diffraction data suggest however, that prewittite may have no close relatives among known minerals and inorganic compounds. This fact astounded researchers who have described the mineral as having separate olive-green tabular crystals up to 0.2 mm in dimension with a vitreous luster and brownish green streaks. It also appears to be orthorhombic, quite brittle and biaxial.

Prewitt was Director of the Geophysical Laboratory from 1986 to 2003. He is presently adjunct professor in the Department of Geosciences at the University of Arizona, in addition to serving as Senior Visiting Investigator at the Laboratory. Prewitt’s many research interests include the characterization of minerals, analogs and new materials. His work on silicates and oxide materials and the development of principles surrounding ionic radii has remained highly influential in the earth and material sciences over the past forty years.


Images: Top: SEM photos of crystals of prewittite. Bottom: Charles T. Prewitt.  Feature Image: Prewittite crystal structure courtesy of Robert Downs, University of Arizona.

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