Journal of the Faculty of Science, Hokkaido University. Series 4, Geology and mineralogy;Vol.XXIII, No.3


An Experimental Study of SiO2 Solubility in Hausmannite

Kikuchi, Takeshi;Sato, Hiroaki;Miura, Hiroyuki

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Solid solubility of SiO2 component in hausmannite has been experimentally determined. The solid solubility of hausmannite coexisting with rhodonite in air at 1200℃ determined by microprobe analyses is the atomic ratio Si/(Mn+Si) of 0.015(2). Reaction between hausmannite and quartz at 900℃ under hematite-magnetite buffer was not attained in equilibrium. Metastable Mn3O4-SiO2 solid solutions have been synthesized in air at 60℃ by a coprecipitation method. The atomic ratio Si/(Mn+Si) is achieved to about 0.025 by this way. It is indicated that the increase of Si content in hausmannite decreases the lattice parameter c and increases a slightly. Concentrations of constituent ions and cation vacancy in hausmannite have been calculated as a function of Po2 and temperature by using a defect chemical equilibrium relations. Possibility to finding the natural hausmannite which is supersaturated with SiO2 is suggested.