<unk> (II,III) oxide is the chemical compound with formula<unk> 3O4. It occurs in nature as the mineral magnetite. It is one of a number of<unk>  oxides, the others being<unk> (II) oxide <unk> O), which is rare, and<unk> (III) oxide <unk> 2O3) which also occurs naturally as the mineral hematite. It contains both<unk> 2+ and<unk> 3+ ions and is sometimes formulated as<unk> O ∙<unk> 2O3. This<unk>  oxide is encountered in the laboratory as a black powder. It exhibits permanent magnetism and is<unk> rrimagnetic, but is sometimes incorrectly described as<unk> rromagnetic. Its most extensive use is as a black pigment. For this purpose, it is synthesized rather than being extracted from the naturally occurring mineral as the particle size and shape can be varied by the method of production.
Iron
Zinc
Copper 
Biotin
Folate
Selenous acid
Calamine
Sybil 