The chemical formula of siderite

Explanation:
The correct chemical formula of siderite, an ore of Fe, is FeCO3 i.e.ferrous carbonate.
Fe2O3 and  Fe3O4 are chemical formulae of haematite and magnetite respectively,both being oxide ores of Fe .
MnO2 of pyrolusite, an ore of Mn.
 
Final Answer:
Hence, the correct answer  is choice C. FeCO3