This study is to determine the nature and causes of compositional variation in lavas from the continuing eruption of Kilauea Volcano, Hawaii. Mineral, glass and whole-rock compositions and Pb, Sr and Nd isotope ratios will be determined and used to evaluate the relative importance of crystal fractionation, magma mixing and mantle melting processes in controlling the composition of the lavas erupted. It is also proposed to evaluate the temporal and spatial variations in the composition of lavas erupted historically at the summit of Kilauea Volcano. This study will evaluate the size and location of the summit reservoir (which are still poorly known), and will be the first to determine modes, mineral and glass major elements, whole-rock major, and trace elements, and O, Pb, Sr and Nd isotope ratios, all on the same samples. Petrological and geochemical results from this study will be integrated with field and geophysical measurements and interpretation made by the staff of the U.S.G.S.