SPECTROSCOPIC INVESTIGATIONS ON DIFFERENT GRADE SAMPLES OF TALC

Three grades of Talc, Mg3[Si4O10](OH)2, collected from Kurnool distric t of Andhra Pradesh, India have been investigated by spectrochemical a nalysis, Optical and EPR spectroscopy. All these samples contain iron as major impurity and trace amounts of Al, Ca, Cr, Cu, Mn and Ni. The Optical absorption spectrum of the high grade Talc sample exhibit six bands at 29403, 26308, 24993, 22720, 20613 and 17090 cm-1, ascribed to Fe3+ impurity, substituted for Mg ion. Low grade Talcs show edge abso rption at 27500 and 22750 cm-1, due to higher content of iron. The cry stal field parameters evaluated are B = 700, C = 2800 and Dq = 700 cm- 1. In addition, the presence of Fe3+ and Mn2+ impurities have been con firmed by EPR spectroscopy. Heating the samples to 850-degrees-C in st eps yielded spectra corresponding to stabilization of iron centres onl y, at the expense of Mn2+ ones.