Tourmaline - natural borosilicate of a complex composition (Henry et al., 2011), space group R3m. Despite the large number of structural refinements Fe3+-bearing tourmalines (~ 50, ICSD) the limiting concentration of iron in different valence states in the structure of tourmaline and a single point of view of the preferred valence of iron in each octahedral site are absent. In this paper based on the structural databases (18 structural determinations; ICSD, AMSCD) analyzed the distribution of cations and structural deformations of Fe3 +-bearing tourmalines.
keywords: crystal chemistry, tourmaline