Mössbauer and infrared spectrometry of lizardite-1T from Monte Fico, Elba

Abstract 

A well crystallized and homogeneous specimen of lizardite from Monte Fico, Elba, Italy, has been studied by Mössbauer and Fourier transform infrared (FTIR) spectrometries. One of the aims was the determination of the oxidation state and the distribution of iron in the structure of this reference sample. Mössbauer data indicate the presence of octahedral ferrous iron, octahedral ferric iron and tetrahedral ferric iron (59.9, 31.3 and 8.8% of total iron, respectively). The existence of only one octahedral site, previously suggested by X-ray structure refinement, is confirmed. The occurrence of tetrahedrally coordinated iron is indicated also by FTIR spectrometry, in particular by the presence of an absorption band at 790 cm^–1. Based also on new electron microprobe data, the improved crystal chemical formula for lizardite from Monte Fico is:

(Mg_2.74Fe²⁺ _0.10Fe³⁺ _0.05Al_0.11)_Σ=3.00

 · (Si_1.94Al_0.05Fe³⁺ _0.01)_Σ=2.00O_5.05(OH)_3.95.