One area of concern accompanying steam injection into siliceous diatomite is the evolution of permeability and porosity as silica dissolves in hot steam condensate and is redistributed on rock surfaces as condensate cools. We employ a network model to gauge how evolving pore topology affects permeability and porosity. The model is anchored to real rock through measured pore-throat and pore-body size distributions. Macroscopic trends are correlated in terms of network connectivity and pore body to throat aspect ratio. When porosity change from 0 to 10% is examined closely, it is found that permeability decrease correlates with porosity decrease according to a power-law expression with power-law exponents in the range of 8 to 9. Such a power-law dependence has been measured previously by experiment(1). These values confirm the strong dependence of permeability on deposited silica. The dissolution process displays an equally strong dependence on porosity change, and again, permeability increases most dramatically for dissolution in networks with small values of connectivity and large values of the pore-body to pore-throat aspect ratio. Power-law expressions adequately describe permeability increase as a function of porosity for a moderate range of dissolution.