CaSiO_3-CaFeSi_2O_6系における鉄バスタム石の水熱合成 : 化学組成と低温安定性について

概要

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Hydrothermal synthesis of ferrobustamite has been carried out at temperatures between 350 and 850 °C, and 100 MPa pressure using CaCO3, FeCl2·4H2O and SiO2 as starting materials. Above 500 °C, formation of ferrobustamite was confirmed by XRD. The FeSiO3 contents in ferrobustamite ranging from 14.7 to 22.9 mol%, and the solid solution range extends towards high FeSiO3 contents with increasing temperature. X-ray microprobe analyses of ferrobustamite showed as tiny grains associated with xonotlite, when it was synthesized hydrothermally at 350 °C from starting material-mixtures of Ca(OH)2, CaCl2·2H2O, FeCl2·4H2O and SiO2. Ferrobustamite was also formed by reheating at 350 °C of the metastable phase with Ca0.9Fe0.1SiO3 held prepared beforehand from a composition between those of ferrobustamite and wollastonite, and quenched from 750 °C. These experimental results suggest that ferrobustamite is stable and there is an immiscibility gap between ferrobustamite and wollastonite at low temperatures around 350 °C, such as the temperature of skarn-formation.
日本鉱物科学会の論文
2008-09-30