2. Local fields in Ca-Na-Fe pyroxene structures, Sapphirine and Surimanite.
The HFS parameters of two doublets in Sapphirine spectra permit us to refer them to two types of M1 polyhedra, typical to the Ca-Fe clinopyroxenes (C2/c). Early for Ge analogs of these clinopyroxenes were determined [Novikov, 2004] two distinct electron structures of Fe 2+ in the Ca-Fe clinopyroxenes (doublets M1 and M1a). The third doublet with the lowest value of guadrupole splitting belongs, apparently, to the Fe 2+ ions in the most deformed cation polyhedra, which are specific for the M2 position of pyroxene structure.
The data on Sapphirines support the idea on important role of distinct M1-M2-T configurations at changing of structural modification of pyroxene, which is attended by the processes of mutual ordering of M1 and M2 cations. This idea was discussed recently at general analysis of data on local structure of Omphacite and Jadeite [Novikov, 2007].