Isomorphism (crystal)
As isomorphism ( gr. Ἴσος ISOS "same" and μορφή morphé "form", "shape") of crystals is defined as the occurrence of various solids in an identical crystal form.
Isomorphism is a prerequisite for the formation of mixed crystals from elements or compounds, whereby two or more elements can occur 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 when the elements involved have the same or very similar atomic radii , see: Goldschmidt rule . A good example is olivine , in which iron (ionic radius 0.86 Angstroms ) and magnesium (ionic radius 0.80 Angstroms) can represent each other. This results in a gapless mixed crystal row between the fayalite Fe 2 SiO 4 and the forsterite Mg 2 SiO 4 .
Individual evidence
- ↑ S. Matthes: Mineralogy. Springer-Verlag, 1993.