On the chemistry of mantle and magmatic volatiles on Mercury

► Redox state of Mercury's mantle is evaluated. ► Inferred reduced conditions correspond to high solubilities of S, Cl, and N in magma and do not favor degassing. ► Mercury's pyroclastic activity may require assimilation of crustal oxides by reduced magma. ► Without magma oxidation by crustal oxides N2 could be the major magmatic gas.