The ore psilomelane can be represented by the overall formula $\text{Ba}((\text{Mn}^{x+})(\text{Mn}^{y+}))_8\text{O}_{16}(\text{OH})_4$. In this overall formula, $x+$ and $y+$ are the two distinct oxidation states of manganese present in psilomelane. What might the values of $x$ and $y$ be?
Chemistry 9701 · AS & A Level · Atoms, molecules and stoichiometry