Original paper

Synthesis of isomorphic vonsenite-ludwigite series

Bloise, A. Barrese


Three intermediate members of the vonsenite (Fe2FeBO5) - ludwigite (Mg2FeBO5) isomorphic series were synthesized at a constant reaction time of 72 hours in various hydrothermal conditions: temperature, 450-700 °C; pressure 500-1000 bar. The starting material and run products were characterized by X-ray powder diffraction (XRPD) and scanning electron microscopy with an energy-dispersive spectrometer (SEM-EDS). Compounds of the isomorphic series were obtained at high temperatures (> 500 °C), at lower temperatures the reactions were only partially completed, resulting in the formation of magnesioferrite and suanite. Structural changes observed in synthetic samples suggest that variations in natural samples are not only related to the presence of various ions replacing Mg and Fe, but also, and mainly, to pressure and temperature variations in the genetic environment during crystallization.


synthetic borateisomorphic serieshydrothermal treatment