Experimental data for high-temperature decomposition of natural celadonite from banded iron formation.

Three experiments were set up to evaluate conditions for the high-temperature decomposition of celadonite from a banded iron formation in an alumina-free system and identify its decomposition products. It was estimated that at 650 and 750 °C, with a NiNiO buffer and pressure of 3 kbar, celadonite completely decomposes and the decomposition products were tetraferribiotite, magnetite and quartz. Under more oxidizing conditions (hematite-magnetite buffer instead of NiNiO), ferrous potassium feldspar sanidine forms instead of magnetite. During the celadonite decomposition in oxidizing conditions more magnesian and aluminous tetraferribiotite, along with ferrous sanidine, are formed than at reducing conditions. [ABSTRACT FROM AUTHOR]