We seek to understand geochemical processes using isotopic ratio and trace element concentration measurements. The research involves measurements of natural Earth systems and materials (rocks, soils, sediments, minerals, pore fluids, etc.) and products from laboratory experiments. The primary objectives are to (1) use isotopic effects to probe molecular- to micro-scale processes that control mineral precipitation and transport in fluid phases, and (2) use the insights gained to understand how to use isotopic measurements to characterize geological fluid-rock systems at their natural (large) scale.