Structure description, interpretation and classification in structural mineralogy
This review provides a summary of the state-of-the-art in terms of description, interpretation and classification of crystal structures in mineralogy. Among the various methods, the focus is on atomic packing (including both anion and cation arrays), coordination polyhedra (both cation- and anion-centred), the concept of fundamental building blocks and related ideas and the use of networks, graphs and tilings (space partitions). The basic concepts under discussion in modern structural mineralogy include structure hierarchy (specification and compositional hierarchies are considered separately), modularity (representation of crystal structures as constructed from modules extracted from simple archetype structures) and complexity (with emphasis on static or informational and algorithmic complexities). Short historical notes are given for all of the topics considered.
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At the dawn of structural crystallography, Walther Friedrich, Paul Knipping and Max von Laue carried out the first experiments and developed the theory of X-ray diffraction. From the early days, when even the simpler inorganic structures filled an entire PhD study, structural crystallography evolved at its own pace and found new partners in chemistry, physics, materials science, biology and other fields of physical sciences. Both morphological and structural crystallography, however, have remained as important instruments in the mineralogist’s toolbox until today. Efforts to enhance the existing instrumentation, to improve our understanding of the theory of diffraction, to study nanoparticulate or poorly ordered materials, and to master large, complex structures continue in all fields of physical sciences. Mineralogy can thus use the fruits of this labour and include them in its toolbox.