Science is built up from facts, as a house is with stones. But a collection of facts is no more a science than a heap of stones is a house.               Henri Poincaré  1854-1912

 

          If Mineralogy is to move beyond descriptive science, it needs a theoretical basis whereby we may understand and predict the structures, chemical compositions and behaviour of minerals in Earth processes at the scale of atoms and chemical bonds. The development of such a basis is the central theme of my work. The patterns of linkage of chemical bonds in space contain significant energetic information that may be used as the basis of a such an approach: Bond topology combines aspects of graph theory, topology, bond-valence theory, and the moments approach to the electronic-energy density-of-states to address many issues that are not addressed by established theoretical methods. I (Hawthorne 2012, 2015, 2018) gave summaries of my then current ideas on Bond-Topology Theory, and Hawthorne & Schindler (2014) described its use in understanding surface reactions of complex minerals in aqueous solution. Hawthorne (2014) put in place a rigorous theoretical framework for the Structure Hierarchy Hypothesis, and derived such hierarchies for oxysalt (sulfate, borate, phosphate, vanadate, borate and beryllate) minerals. I have begun working on silicate minerals (sheet silicates: Hawthorne et al. 2019); chain-ribbon-silicates: Day & Hawthorne 2020) and have put in place a mathematically rigorous graph-theoretic approach to deriving all possible connectivities of tetrahedra and discovering what controls their occurrence in crystal structures (Day & Hawthorne 2022, 2024a,b).

In parallel with my theoretical work, my long-term experimental research program is based on the idea that the more complex (sensu lato) a mineral, the more information it contains about its origin. I use crystal-structure determination and refinement in conjunction with many forms of spectroscopy (polarized infrared and Raman, Mössbauer and milli-Mössbauer, Magic-Angle-Spinning Nuclear Magnetic-Resonance, X-ray Photoelectron Spectroscopy, XANES and EXAFS), HRTEM, and micro-beam analysis (electron-microprobe, PIXE, SIMS and analytical SEM) to characterize a wide range of complicated minerals and get a sense at the atomic scale for what underlies their existence as discrete minerals and controls their behaviour in Earth processes. This wide range of seemingly disparate experimental topics is focused on developing a rigorous and comprehensive understanding of the structures, chemical compositions and behaviour of minerals.