[en] A low Al, low Ca enstatite from within an orthopyroxenite dyke rock in the Sukinda chromite field was physico-chemically investigated by use of ⁵⁷Fe Moessbauer spectroscopy, XRF and XRD. The parameters of the fitted ⁵⁷Fe Moessbauer spectra show the presence of Fe³⁺ in the octahedral M1 site of pyroxene structure. The room temperature Moessbauer results show three doublets corresponding to Fe²⁺(M1), Fe²⁺(M2) and Fe³⁺(M1) sites. The QS values in two samples are found to be 2.80 and 2.96 mm/s for Fe²⁺(M1), and 1.89 and 2.08 mm/s for Fe²⁺(M2) doublets. In both samples Fe³⁺(M1) gives IS values 0.38 and 0.56 mm/s and QS values 0.48 and 0.49 mm/s. From their dependence on X_Msup(Fe)sup(21)1 and X_Msup(Fe)sup(21)2 distributions the bond distances of tetrahedral and octahedral sites have been measured. In the present case Fe³⁺ in the orthopyroxene structure is presumed to have been formed primarily at the stage of its crystallisation from a melt having requisitely high fO₂. The temperature recorded by the Sukinda orthopyroxenite body has been estimated as 800degC from the distribution of Fe²⁺-Mg over M1 and M2 sites. From the Fe³⁺/Fe²⁺ ratio the oxygen fugacity has been calculated as log fO₂=-6.189, which suggests that crystallisation of Sukinda orthopyroxene took place in the lower crystal regions rather than in the mantle. (author). 30 refs., 4 tabs., 2 figs