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The mineral chapmanite is an iron-antimony silicate, an uncommon but potentially significant sink of the toxic element antimony in the environment. In this work, we have investigated the thermodynamic properties of these minerals by a combination of calorimetric techniques. The goal was to find out when could chapmanite form and why is it not more abundant. The results show that under very specific conditions, it is almost, but not quite, stable with respect to more common tripuhyite (FeSbO4) or schafarzikite (FeSb2O4). It could be stabilized in solutions that carry high amount of silicic acid. Sheet silicates may adsorb Sb3+ and create chapmanite-like surfaces but the crystallization of chapmanite under low-temperature conditions is unlikely. This work contributes to our understanding of geochemical mobility of antimony and more details can be found under https://doi.org/10.5194/ejm-33-357-2021Externer Link
