This grant, made through the Major Research Instrumentation (MRI) Program, provides partial support of the costs of acquiring a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS) for major elemental compositional mapping and semi-quantitative spot analyses of geological and biological samples at Dickinson College, an undergraduate institution in Carlisle, PA. In addition to its use as an educational tool involving undergrads in meaningful research projects, Dickinson faculty will make use of the EDS-SEM for studies of the petrogenesis of arc magmas, geochemical investigations of Quaternary tephras and Ordovician K-bentonites, and trace element investigations of bryozoan skeletons. ***