Metamorphic

Part of speech: adjective (a.)

1. Subject to change; changeable; variable.

2. Causing a change of structure.

3. 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.