Modular structures are built by modules (blocks, rods, layers) which differ either in the chemistry or in the crystallographic orientation / position. They include polytypes and OD structures, polysomatic and homologous series, cell-twins, as well as twins and epi/syntaxies as limiting cases. The structure-building principle allows fine tuning of both structure and chemical composition and can be seen as the rationale behind the well-known phenomenon of morphotropism which dates back to von Groth. It represents one of the most outstanding mechanisms by which Nature produces a wide range of minerals from a relatively limited number of building blocks. The understanding of the features of these minerals represents thus a challenge both for the experimental mineralogist and for the theoretician, and opens a huge horizon for crystal engineering of natural materials as well as man-made materials for which minerals are used raw ans starting material.
University of Lorraine
Italian citizen but working in France, MSc in Chemistry, University of Torino (Italy), DrSc in Mineralogy, The University of Tokyo (Japan), currently Full Professor of Crystallography and Mineralogy at the CRM2 Laboratory Nancy (Université de Lorraine and CNRS), founder and past Chair of the Commission on Mathematical and Theoretical Crystallography of the International Union of Crystallography.
- Sergey Krivovichev (Russia), St. Petersburg State University
- Isabella Pignatelli