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Mode of Occurrence of Minerals

 Ores

  • Minerals are usually found in ores.
  • Ore = accumulation of any mineral mixed with other elements.
  • Mineral content should be sufficiently high for economic extraction.

Formation of Minerals

  1. Veins & Lodes

    • Minerals occur in cracks and cavities of igneous/metamorphic rocks.
    • Examples: Copper, zinc, lead, etc.



  2. Evaporation

    • Minerals are formed when water evaporates, especially in arid regions.
    • Examples: Salt, gypsum.




  3. Weathering

    • Surface rocks decompose.
    • Soluble materials are removed.
    • Residual material contains minerals.
    • Example: Bauxite.


  4. Placer Deposits

    • Found in alluvial deposits in sands of valley floors and hill bases.
    • Usually contain minerals resistant to erosion.
    • Examples: Gold, silver, tin, platinum.

  5. Ocean Deposits

    • Ocean water contains large quantities of minerals.
    • Common salt, magnesium and bromine are obtained from ocean water.
    • Ocean beds contain manganese nodules.

Distribution of Minerals in India

  • Mineral resources are unevenly distributed.
  • Peninsular rocks: coal, metallic minerals, mica and many non-metallic minerals.
  • Western & eastern flanks: sedimentary rocks and petroleum deposits.
  • Gujarat & Assam: major petroleum reserves.
  • Rajasthan: many non-ferrous minerals.
  • Northern alluvial plains: almost devoid of economic minerals.
  • Distribution depends on:
    • Geological structure
    • Geological processes
    • Time involved in mineral formation

Ferrous Minerals

  • Account for about ¾ of the total value of metallic mineral production.
  • Form the base for metallurgical industries.
  • India exports substantial quantities of ferrous minerals.

Iron Ore

  • Basic mineral + backbone of industrial development.
  • India has abundant iron-ore reserves.
  • Major types:
    • Magnetite: finest quality; iron content up to 70%.
    • Hematite: most important industrial iron ore; iron content about 50–60%.

Major Iron-Ore Producing States

2009–10 share:

  • Odisha – 33%
  • Jharkhand – 28%
  • Chhattisgarh – 19%
  • Karnataka – 11%
  • Others – 9%

Rat-Hole Mining

  • Common in Meghalaya.
  • Coal is extracted through narrow tunnels.
  • Tunnels are so narrow that they resemble rat holes.


  • Mining is traditionally done by family members.
  • Minerals in most tribal areas of Northeast India are owned by individuals or communities.



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