Which of the following is an iron ore ?

Explanation

Among the given options, limonite is an iron ore. Its chemical formula is FeO(OH).nH2O. Magnetite, hematite, siderite etc. are other major iron ores. Among the other options, cinnabar is an ore of mercury, while bauxite is an ore of aluminium. Pyrite or iron pyrite (chemical formula FeS2) also contains iron, but this sulphide mineral is used commercially mainly for producing sulphur dioxide and sulphuric acid, and it is generally not used as an iron ore.