This text presents research on the chemical interaction of aqueous fluids with the rock matrix containing them. The contributions come from a wide variety of geologic settings and include groundwater-aquifer reactions, hydrothermal fluids in volcanic and ore deposit environments and water-rock interaction in geothermal areas. The focus is on upper crustal and near surface environments. The presented research comprises field studies as well as experimental work. The book adds new data and understanding to the multifaceted general process of chemical interaction of water and rock.