Paramorphism

paramorphism

[¦par·ə′mȯr‚fiz·əm]

(mineralogy)

The property of a mineral whose internal structure has changed without change in composition or external form. Formerly known as allomorphism.

Paramorphism

 

a type of pseudomorphism that involves the polymorphous alteration of a high-temperature form of a mineral to a low-temperature form. With paramorphism there is a rearrangement in the crystalline structure of the mineral without a change in chemical composition; the external shape of the original crystal is also preserved. Examples of paramorphs are hexagonal α-quartz after trigonal β-quartz, rhombic sulfur after monoclinic sulfur, trigonal calcite after rhombic aragonite, and cubic pyrite after rhombic marcasite.