Mössbauer spectra study on Xiu-Yan Jade

Having beautiful colours and fine features, Xiu-Yan Jade is famous in the world. Mineralogically, Xiu-Yan Jade is serpentine jade. XRD, IR and TEM study indicate that the jade consists mainly of antigorite (m{Mg_3(1?1/m)Si₂O₅](OH)_1+3(1?2/m)}) with a minor amount of chrysotile. Two favourite samples (P_XA, P_X1?t) are chosen for research on⁵⁷Fe Mössbauer spectra. Two sets of quadrupole doublets are obtained from the spectra, The parameters of two samples, 1. 124 mm/s and 1. 119 mm/s of I. S. and 2. 732mm/s and 2. 716mm/s of Q. S. for Fe²⁺ in the octahedral and 0. 364mm/s and 0. 351mm/s of I. S. 0. 632 and 0. 546mm/s of Q. S. for Fe³⁺ in the octahedral, are only antigorite. Studies indicate that: (1) iron—ion in antigorite enters the lattice as impurity: (2)Fe²⁺ and Fe³⁺ substitute for Mg in the coordination octahedron: and (3) the colour of jade is related to content of Fe, and Fe³⁺/Fe²⁺≤1 is favourite for colour—forming.