Next nearest neighbor effects in triphylite and related phosphate minerals

Abstract

Phosphate minerals of triphylite, ferrisicklerite and purpurite were investigated using Mössbauer spectroscopy. The crystal structures of these three minerals are alike to that of olivine except no atoms in the M1 site of purpurite structure. Mössbauer spectra of these minerals at 298K are composed of the multiple doublets with nearly equal isomer shifts but slightly different quadrupole splittings. These multiple doublets are assigned to Fe²⁺ or Fe³⁺ in the M2 sites, showing that the next nearest neighbor(NNN) effect exists in the Mossbauer spectra of these minerals.