Minerals presenting pseudomorphosis, epimorphs or perimorphosis, natural phenomena by which a mineral species replaces another while keeping the shape of its crystals (pseudomorphosis), or covers and molds crystals of another mineral species, taking their shapes. Epimorphs or perimorphosis exists when a second mineral coats a previous mineral .
Pseudomorph: a mineral sample with the external crystal form of one mineral and the internal chemistry of another.
Epimorph: type of pseudomorph where a mineral replaces another mineral and the original mineral dissolves, leaving a hollow cast surrounded by the new mineral.