Arsenolite is an arsenic mineral, chemical formula As₂O₃. It is formed as an oxidation product of arsenic sulfides. Commonly found as small octahedra it is white, but impurities of realgar or orpiment may give it a pink or yellow hue. It can be associated with its dimorph claudetite (a monoclinic form of As₂O₃) as well as realgar (As₄S₄), orpiment (As₂S₃) and erythrite, Co₃(AsO₄)₂·8H₂O.