The principal investigator, in collaboration with Dr. Melinda Dyar of the University of Oregon, will study the crystal chemistry of coexisting biotite, muscovite, and chlorite from several different representative rock provenances. Electron microprobe, Mossbauer, and other analytical techniques will be utilized. The work will lead to a better understanding of the location of vacancies in the structures of these minerals. It also will lead to a better understanding of the chemical substitutions that occur in the minerals and of the controls on the partitioning of ferric iron and hydrogen among crystallographic sites in the minerals, as well as between mineral pairs. These data will be of importance to geologists who use these minerals to estimate the geologic conditions of formation of rocks in which the minerals occur.
