Process of simultaneous solution and deposition in which one mineral replaces another.
It is the method by which wood is petrified (silica replaces the wood fibres), minerals form pseudomorphs (new minerals that preserve the characteristic outward form of the earlier mineral that was replaced), or an ore mineral assemblage takes the place of an earlier rock type. Replacement minerals may themselves be replaced, and definite mineral successions have been established. Replacement deposits may be highly valuable ore deposits.