Subject to change; changeable; variable.

Causing a change of structure.

Pertaining to, produced by, or exhibiting, certain changes which minerals or rocks may have undergone since their original deposition; -- especially applied to the recrystallization which sedimentary rocks have undergone through the influence of heat and pressure, after which they are called metamorphic rocks.

Geology having undergone changes of mineralogy and texture imposed on it by pressure and temperature in the Earth's interior.