Preliminary results of ⁵⁷Fe Mössbauer spectroscopy of metamict samarskite after one-hour high temperature annealing in argon

The preliminary results of ⁵⁷Fe Mössbauer spectroscopy and X-ray diffraction (XRD) of fully metamict samarskite dated at ~1500 Ma, which absorbed α-dose of 6.5 × 10¹⁷ α-decay mg^-1, are reported after one-hour annealing at 673, 873, 1173 and 1373 K in argon atmosphere. Metamict minerals contain radioactive elements that degrade their crystal structures over geological time. All the Mössbauer spectra obtained can be fitted to two quadrupole doublets assigned to Fe²⁺ and Fe³⁺ in octahedral positions. The relative contribution of Fe²⁺ (Fe²⁺/Fe) reaches a minimum of 0.10 at 1173 K.