The Ministry of Mines has classified limestone as a major mineral across all uses.

• Previously, limestone used in kilns for lime manufacture was categorized as a minor mineral, while limestone used in cement, chemicals, fertilizer, steel, and other industries was considered a major mineral.

Impact on Industry and Business

• Ease of Business: The new classification removes the regulatory distinctions that previously restricted the sale or use of limestone based on its intended purpose. This will allow leaseholders to sell or use limestone freely, boosting market access.
• Increased Availability: The decision is expected to increase limestone availability to cement industries, facilitating their growth and the expansion of cement manufacturing capacity in India, essential for infrastructure and construction.
• Enhanced Rural Employment: By allowing broader usage, this move is anticipated to increase income and employment in rural areas, where limestone is abundant.

Major vs Minor Minerals in India

• Mines and Minerals (Development and Regulation) Act, 1957 (MMDR Act, 1957): The primary legislation governing mineral resources in India. It classifies minerals into two categories: Major Minerals and Minor Minerals

Classification Criteria

• Major Minerals: Typically have high economic value and are used in large-scale industries. Their extraction and regulation are under the control of the Central Government.
  • The Indian Bureau of Mines (IBM) plays a significant role in the administration and regulation of major minerals.
• Minor Minerals: Generally have lower economic value and are used in local or small-scale applications. Their extraction and regulation are primarily under the control of State Governments.

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About Limestone

• Primary Composition: Limestone is a sedimentary rock predominantly composed of calcium carbonate (CaCO₃), primarily in the forms of calcite or aragonite.
• Formation Processes:
  • Biogenic: Accumulation of organic materials such as shells, corals, and foraminifera in marine environments.
  • Chemical: Precipitation of calcium carbonate from water, often in caves or hot springs, leading to formations like travertine and tufa.
  • Evaporitic: Formation through evaporation processes in lakes or shallow seas.
• Properties:
  • Color: Ranges from white to gray; impurities can impart yellow, brown, or red hues.
  • Hardness: Generally soft to moderately hard.
  • Reactivity: Effervesces with dilute hydrochloric acid due to the presence of calcium carbonate.
  • Porosity: Varies widely; influences its suitability for various applications.
• Types of Limestone:
  • Fossiliferous Limestone: Contains abundant fossil fragments; useful in studying past life forms.
  • Coquina: Composed mainly of shell fragments; porous and lightweight.
  • Chalk: Fine-grained, soft, and white; formed from microscopic marine organisms.
  • Travertine: Formed by the evaporation of water in caves or springs; banded and often used in decorative applications.
  • Oolitic Limestone: Composed of small spherical grains called ooids; formed in warm, shallow marine environments.
• Economic Importance: 
  • Construction Material: Used in building materials such as cement, concrete, and as dimension stone in architecture.
  • Industrial Applications:
    • Lime Production: Heating limestone produces quicklime (CaO) and slaked lime (Ca(OH)₂), essential in various chemical processes.
    • Soil Amendment: Used to neutralize acidic soils in agriculture.
    • Flue Gas Desulfurization: Employed in power plants to remove sulfur dioxide from exhaust gases.
• Environmental and Geological Significance:
  • Karst Landscapes: Limestone’s solubility leads to the formation of unique landforms like caves, sinkholes, and limestone pavements.
  • Fossil Record: Rich in fossils, limestone provides valuable insights into Earth’s history and past climates.

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