THE STRUCTURE AND ELECTRON-DENSITY OF FE2-BEARING TAVORITE IN RELATION TO THE GENETIC CRYSTAL-CHEMISTRY OF SECONDARY PHOSPHATES OF LITHIUM PEGMATITES()

Ferrous iron cations were localized in an independent octahedral posit ion based on the precision X-ray diffraction study, including analysis of the deformational electron density of the black synthetic tavorite . A model explaining color of the crystals has been suggested. The pos ition of the hydrogen atoms in tavorite's structure has been identifie d for the first time. The structural relationship established in the t avorite-Fe2+-bearing tavorite-barbosalite series is a crystal chemistr y's reason for paragenesis ''tavorite-barbosalite'' in lithium pegmati tes.