Mossbauer Study of Iron in Minerals from the Wall-Rock Zone of the Kusa Ilmenite-Magnetite Deposit,Southern Urals

摘要

This paper presents the results of a Mossbauer spectroscopic study of the behavior of iron ions in minerals(amphibole,ilmenite,and staurolite)from the contact of ore bodies and host gabbroids of the Kusa ilmenite-magnetite deposit.Regular variations were observed in the degree of iron oxidation in these minerals in the wall-rock zone.It was shown that during the stage of high-pressure acid leaching,when oxygen potential increased,the decomposition of primary amphibole was accompanied by the formation of a less oxidized amphibole variety and magnetite,while ilmenite and staurolite became more oxidized.The multivariate analysis of the distribution of hyperfine parameters derived from the Mossbauer spectra of amphiboles was performed;the obtained parameters for individual nuclear states of iron can be considered as reference values for amphibole-group minerals.In staurolite,ferrous iron occupies the most distorted T_2(2)tetrahedral sites and intermediately distorted T_2(3)sites,and the samples usually show low contents of Fe~(2+)in the octahedral M_4 sites.The data obtained for the Kusa samples were compared with those for natural(from metamorphic rocks)and synthetic staurolites.Ilmenite from the Kusa deposit is represented by a partially oxidized variety,ferriilmenite.