Prof. Stewart’s research interests are primarily in the field of high temperature geochemistry and igneous petrology. He has current projects investigating the origin of andesitic dikes in the Wasatch Igneous Belt of Utah, the origin of mafic enclaves in the Alta Stock of the Wasatch Range, Utah, stable-Cl isotope systematics in igneous systems, and volcanism and lithospheric recycling on Jupiter's moon Io. His past work has included a geochemical investigation of mafic dikes and lavas recovered from the Pacific Ocean crust using the deep submersible Alvin.