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Etude expérimentale de la solubilité du chrome dans les bains silicatés basiques et de sa distribution entre liquide et minéraux coexistants : conditions d'existence du spinelle chromifère

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1982

Year

Abstract

The solubility of chromium in basic silicate melts was studied experimentally. Runs were carried out at temperatures of 1180-1300°C and oxygen fugacity of 10⁻³ -10⁻⁹ atm, at one atm total pressure. The Cr content of the liquid in equilibrium with chromian spinel increases when temperature increases, and / or when oxygen fugacity decreases, the range of variation being 170-1460 ppm. The partition coefficient D = (Cr₂O₃)sp / (Cr₂O₃)liq, which varies between 257 and 1424, is affected by temperature variations more than by variations of oxygen fugacity. It is pointed out that variations of temperature and / or oxygen fugacity may induce chromium sursaturation in the melt, and consequently crystallization of spinel. The conditions of coexistence of chromian spinel with clinopyroxene are established.