NEW CALIBRATION AND SOME APPLICATIONS OF SPHALERITE COSMOBAROMETER

The sphalerite-troilite-metallic iron equilibrium in the Zn-Fe-S syste m was studied by crystallization method in halogenide solution-melt at 400-600-degrees-C and 1 bar of pressure. The maximal FeS content in s phalerite could be expressed by the linear equation: N(Fes)Sph = 43.90 + + 0.0127T (K). The influence of pressure on FeS solubility in sphal erite was studied theoretically. The calculated solubility isobars wer e found to be in a good agreement with the experimental data of Hutchi son and Scott (1983). New approximation procedure in respect of high p ressure solvus is presented. The former is based on the numerical inte gration of differential equations of solution thermodynamics. A nomogr am for pressure estimation using the data on sphalerite chemical compo sition and blocking temperature of diffusion is presented. New estimat es of pressure values in respect of iron meteorites are not above 2.3 kbar.