Cacoxenite is an iron aluminium phosphate mineral with formula: Fe³⁺₂₄Al(PO₄)₁₇O₆(OH)₁₂·17(H₂O). It is associated with iron ores. The name comes from the Greek κăκός for "bad" or "evil" and ξένος for "guest" because the phosphorus content of cacoxenite lessens the quality of iron smelted from ore containing it.