noun.
The act of altering; the making of any change; passage from one form or state to another.
noun.
A change effected; a change of form or state, especially one which does not affect the identity of the subject.
noun.
In mineralogy, the change by which one mineral substance is converted into another, either with or without change of chemical composition; as, for example, the change of the oxid of copper, cuprite, to the carbonate, malachite; or of brookite to rutile, both being forms of titanium dioxid. See paramorphism and pseudomorphism.