Which of the following is an iron ore?

General Science ·Previously asked in BPSC CCE 2024

View the full solved paper: GS 2024 (Series G)

Question

Which of the following is an iron ore?

  1. A. Cinnabar
  2. B. Bauxite
  3. C. Limonite (Correct answer)
  4. D. Pyrite

Correct Answer

Option C — Limonite

Detailed Solution & Explanation

The correct answer is Limonite.

Key Points

  • Limonite is an ore of iron — a hydrated iron oxide (roughly Fe2O3·H2O) that is yellowish-brown in colour.
  • Along with haematite, magnetite and siderite, it is one of the principal ores from which iron is extracted.
  • The other minerals are ores of different metals: Cinnabar is the chief ore of mercury (HgS); Bauxite is the main ore of aluminium; and while Pyrite (FeS2, 'fool's gold') does contain iron, its high sulphur content makes it unsuitable as a commercial iron ore — it is used mainly to produce sulphuric acid.
  • Therefore, among the given options, Limonite is the correct iron ore.

Additional Information

  • The four principal iron ores by iron content: magnetite (Fe₃O₄, ~72%), haematite (Fe₂O₃, ~70%), limonite (~60%) and siderite (FeCO₃, ~48%).
  • India's reserves are overwhelmingly haematite, concentrated in Odisha, Jharkhand and Chhattisgarh; magnetite occurs mainly in Karnataka.
  • Magnetite is naturally magnetic, the property that gives it its name and an easy identification test.