Crystal-Chemical Indicators of Specification of Oxocentered Tetrahedra in Divalent Lead Minerals

A complex crystal-chemical analysis of 1567 oxygen positions in 216 crystal structures of lead-containing minerals assigned to the classes silicates, phosphates, oxides, oxohalides, and a number of others has been performed. It is shown that the combined application of the bond valence method and analysis of geometric characteristics of Voronoi–Dirichlet polyhedra makes it possible to reliably distinguish between oxygen positions related to cation structure blocks and oxygen positions, for which a description based on an anion-centered approach is more reasonable. Numerical indicators for such separation of oxygen positions are substantiated, which can be used to analyze large arrays of structural data, using the machine learning approaches.