A charming space sandbox that will keep you busy and entertained for hours. Like most polymeric oxides, Sb 2 O 3 dissolves in aqueous solutions with hydrolysis.A mixed arsenic-antimony oxide occurs in the nature as the very rare mineral stibioclaudetite. Antimony(III) oxide is the inorganic compound with the formula Sb 2 O 3.It is the most important commercial compound of antimony.It is found in nature as the minerals valentinite and senarmontite.