transformation [cryst] (trans-for-ma'-tion). Transformation is remodeling of an existing mineral structure in which major parts of at least the geometry, and usually structural elements of the parent mineral are retained. The change from one crystal polymorph to another, by one of several processes. See: dilatational transformation; displacive transformation; reconstructive transformation; rotational transformation; substitutional transformation; order-disorder transformation. Syn: inversion [cryst]; phase transformation.