TIN-BEARING ALUMINOSILICATE SYSTEMS IN HIGH-TEMPERATURE PROCESSES UNDER VARIABLE REDOX CONDITIONS

Experimental results on the state and migration properties of tin in a luminosilicate glasses as a function of temperature and redox conditio ns are presented. The composition of the glasses approximate those of the main igneous rock compositions. The valence of the Sn and Sn2+/Sn4 + ratio in aluminosilicate phases synthesized at the liquidus temperat ure and within the fO(2) range typical of natural magmatic systems wer e determined with Mossbauer spectroscopy; the same determinations were carried out in samples of rocks of respective composition heated to 5 00 degrees C under oxidizing conditions. The Sn2+/Sn4+ ratio in the in itial acid rock samples is higher than in the basaltic rocks. A substa ntial increase in Sn4+ content in phases heated to 500 degrees C in ai r was was detected simultaneously with an insignificant change in the Fe oxidation state. ESCA data on the surface layer mineral grains in t he initial and heated samples Sn contents in acid solutions that react ed with them testify to the lack of noticeable tin redistribution or i ncrease in its mobilization properties with the change of redox potent ial.