Strike-parallel flow of H2O-rich fluids through Reynolds Range marbles formed wollastonite-bearing assemblages. Wollastonite abundance varies on a millimetre de from 10 to 66 modal%. The mineralogy of unmetasomatized marbles suggests that the formation of more than c. 19% wollastonite requires silica metasomatism. Comparison with advective transport models suggests that the variable wollastonite contents may be explained by time-integrated fluid fluxes and intrinsic permeability varying by up to two orders of magnitude on a millimetre scale. Fluids were probably focused through the marble within microfractures and the variations in intrinsic permeability may reflect variable fracture density.