Isomorphism (crystallography)

As an isomorphism (Greek ἴσος isos "equal" and μορφή morphé "form", "shape" ) of crystals defined as the occurrence of various solids in an identical crystal form.

Isomorphism is a prerequisite for the formation of mixed crystals of elements or compounds in which two or more elements may be present in variable proportions. The phenomenon was first described in 1819 by the German naturalist Eilhard Mitscherlich. Victor Moritz Goldschmidt later showed that this is possible if the elements involved have the same or very similar atomic radii, see: Gold Schmidt's rule. A good example is the olivine in which iron ( ionic radius 0.86 Angstroms) and magnesium ( ionic radius 0.80 Angstroms) can represent each other. This results in a complete solid solution series between the fayalite and forsterite Mg2SiO4 Fe2SiO4.