paramorphism

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Structural alteration of a mineral without change of chemical composition.

from The Century Dictionary.

• noun In mineralogy, a change of the molecular structure of a mineral without alteration of external form or chemical constitution: a variety of pseudomorphism. See paramorph and pseudomorphism.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Min.) The change of one mineral species to another, so as to involve a change in physical characters without alteration of chemical composition.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun geology a change in the physical structure of a mineral without any chemical change