MOSSBAUER, OPTICAL AND EPR SPECTRAL STUDIES OF ALUNITE

Mossbauer, optical and EPR spectral studies are made on alunite minera l. The Mossbauer spectrum of alunite exhibit the characteristic patter n of Zeeman hyperfine splitting of iron. It shows the magnetic orderin g of the sample and the calculated internal field is 523 kG. The isome r shift and quadrupole splitting are delta = 0.3757 and QS = 0.155 mm s-1 indicating the presence of iron in the Fe3+ state with antiferroma gnetic nature. The optical absorption studies suggest octahedral symme try for Fe3+ in the sample. Three strong and sharp lines in the EPR sp ectrum with g values 7.984, 5.791 and 3.962 suggest a large anisotropy for Fe3+ in the sample. The EPR spectrum also reveal the presence of vanadium and manganese as trace impurities in the sample.