A quantitative model of transport and chemical reaction is developed to examine the interplay of physical and chemical processes controlling the evolution of black smoker chimneys. Diffusion and advection yield steady state profiles of temperature and concentration across a porous wall bound on one side by hydrothermal fluid and on the other by seawater. The pressure gradient is estimated from the fluid dynamics of high-velocity flow inside the chimney. Parametric studies reveal the importance of diffusion driven by gradients in activity coefficients resulting from the strong thermal gradient. The model wall is a series of vertical layers, each with specified physical properties. Chemical reaction, calculated assuming chemical equilibria for the local temperature and concentration conditions, significantly modifies the physical properties of the wall as it evolves. Model calculations demonstrate the sensitivity of mineral zonation to the physical environment and can be used to re-create the aging of chimneys inferred from petrologic studies. ¿ American Geophysical Union 1990