Graduate student Jeffrey Marsh discovers a new mineral
In the course of carrying out research for his Ph. D. thesis in the Department of Earth Sciences, Jeffrey Marsh became the first student at the University of Maine ever to discover a new mineral species, which was published in the October 2010 issue of The Canadian Mineralogist. Jeff’s new mineral, menzerite-(Y), is a species of garnet named for the German crystallographer Georg Menzer (1897-1989), who in 1925 was the first to solve the crystal structure of the garnet group. The suffix “-(Y)” indicates the dominance of the metal yttrium in this new garnet.
The mineral and name was approved in 2009 by the Commission on New Minerals and Mineral Names of the International Mineralogical Association, which officially recognized the discovery of this new mineral. Menzerite-(Y) was one of the 97 new minerals proposed in 2009, 91 of which have been approved. Recognition of new minerals follows a complex protocol and careful scientific review by the Commission, which consists of 38 officers and members from 34 countries.
Jeff successfully defended his thesis “Interactions among metamorphism, deformation, and chemical transport processes in high strain crustal rocks” on July 29, 2010 and is now a Faculty Fellow at Colby College. He discovered menzerite-(Y) in a rock which had crystallized at high temperatures in his thesis field area of Parry Sound, Georgian Bay, Ontario. He recognized that brown cores in the common garnet species almandine in one rock must be a different mineral, and qualitative chemical analyses on the department’s electron microprobe showed the brown cores to be a silicate mineral with a high yttrium content. Menzerite-(Y) differs from almandine, a garnet rich in iron and aluminum, because the iron and aluminum are largely replaced by calcium, yttrium and the rare earth elements, the last very similar to yttrium chemically. Menzerite-(Y) grains are microscopic (less than 70 micrometers or 0.003 inch across) and thus were a challenge to study. The photomicrograph shows menzerite-(Y) overgrown by almandine as seen under the optical microscope, while the diagram is based on X-ray study of this intergrowth.
Minerals of the garnet group find wide applications in industry as an abrasive and for water filtration, whereas synthetic varieties are used as a lasing medium and in magnetic films. Garnets are among the most useful minerals to scientists for deducing the pressure-temperature conditions deep in the Earth’s crust and mantle.
The scientific paper officially reporting menzerite-(Y) was published this year in the October issue of The Canadian Mineralogist (volume 48, pages 1171-1193) under the title “Menzerite-(Y), a new garnet species, {(Y, REE)(Ca, Fe2+)2}[(Mg,Fe2+)(Fe3+,Al)](Si3)O12, from a felsic granulite, Parry Sound, Ontario, and a new garnet end member, {Y2Ca}[Mg2](Si3)O12,” by Edward Grew, Jeffrey Marsh and Martin Yates of the University of Maine; Biljana Lazic and Thomas Armbruster of the University of Bern; Andrew Locock of the University of Alberta; Samuel Bell of Amherst College; Darby Dyar of Mount Holyoke College; and Heinz-Jürgen Bernhardt and Olaf Medenbach of the Ruhr-University. Characterizing the new mineral required a multidisciplinary approach involving a large number of specialists. Martin Yates, Laboratory Manager in the Department of Earth Sciences, and Jeff Marsh carried out the chemical analyses on the electron microprobe at the University of Maine, whereas the other co-authors contributed crystallographic, computational, optical and X-ray absorption spectroscopy.
The National Science Foundation and University of Maine Doctoral Research Fellowship sponsored the research by Jeff and the Maine team.