Original paper

Synthesis of ludwigite along the Mg2FeBO5 Mg2AlBO5 join

Bloise, A.; Barrese, E.; Apollaro, C.; Miriello, D.

Abstract

bearing ludwigite on the Mg2(Al,Fe)BO5 - Mg2AlBO5 join was synthesized in a standard externally-heated pressure vessel over a temperature range of 600-700 °C, with pressures of 500-1000 bar, for a period of three days. Four starting mixtures were used: (1) Mg2(Fe0.75Al0.25)BO5, (2) Mg2(Fe0.5Al0.5)BO5, (3) Mg2(Fe0.25Al0.75)BO5, and (4) Mg2AlBO5. Products were examined by X-ray diffraction (XRPD) and electron microscopy with an energy-dispersive spectrometer (SEM/EDS). In these experimental conditions, single-phase Al-bearing ludwigite was only obtained at high temperature and pressure (700 °C, 1000 bar), since reactions were only partially completed at lower temperatures and pressures. The chemical composition of Al-bearing ludwigite was generally close to that of the starting materials, especially for those with lower aluminum content. Variations in cell parameters were nearly linear, as a function of composition. These results may improve our understanding of the varied occurrence of natural Al-rich ludwigite minerals.

Keywords

hydrothermal experimentssynthesisal-bearing ludwigitecharacterizationxrpd cell dimensions