Classification of Minerals: Characteristics, Metallic Content, Origin

Geologists define a mineral as a “homogenous, naturally occurring substance with a definable internal structure.” Minerals are natural substances found in different forms, from tough diamonds to soft talc. They’re diverse because they form under different conditions, leading to variations in colour, hardness, and shape. Geologists use properties like colour and hardness to classify minerals.

Understanding Minerals: Types and Classification

• Nature’s Diversity: Minerals vary greatly due to different physical and chemical conditions when they form. 
  • This leads to differences in colour, hardness, shape, etc.
• Minerals in Rocks: Rocks are made up of minerals. Some rocks have only one mineral, like limestone, while others have several. 

• Types of Mineral Occurrence:

• • In Igneous and Metamorphic Rocks: Minerals can be found in cracks, faults, or veins. 
    • Example: Tin and copper are obtained from veins.
  • In Sedimentary Rocks: Minerals form in layers through deposition and concentration. 
    • Examples: Coal and some iron ores are examples.
  • Residual Formation: Weathering breaks down rocks, leaving behind ore-rich material. 
    • Example: Formation of Bauxite.
  • Alluvial Deposits: Some minerals accumulate on valley floors and hillsides as placer deposits.
    • Example: Gold and Platinum, 
  • Minerals from Ocean: Ocean waters contain minerals like salt, magnesium, and bromine, while manganese nodules are found in ocean beds.
• Uneven Distribution in India: India’s mineral wealth is distributed unevenly due to differences in geological structure and processes. 
  • Peninsular rocks hold most coal, metallic minerals, and mica, 
  • Sedimentary rocks in Gujarat and Assam have petroleum. 
  • Rajasthan has non-ferrous minerals, and north India’s plains lack economic minerals.
• Economic Viability: The concentration of minerals in ore, ease of extraction, and proximity to markets determine their economic viability. 

Classification of Minerals

1. Based on Characteristics: Minerals are classified into major and minor minerals:

• Major Minerals: Abundantly present in the Earth’s crust; major minerals.
  • Example: such as Coal, Iron ore, Bauxite, Copper, Gold, and Limestone, significantly contribute to the economy.
• Minor Minerals: Occurring in smaller quantities, minor minerals like Mica, Garnet, Barite, Talc, Beryl, and Silica sand have limited economic importance. 
  • Extracted on a smaller scale, they find usage in niche applications.

2. Based on Metallic Content:minerals are classified into metallic and non-metallic minerals:

• Metallic Minerals: Primarily valued for their metal content, metallic minerals like Gold, Silver, Copper, Iron ore, Zinc, Lead, and Aluminum exhibit a characteristic metallic luster, high electrical and thermal conductivity. 
  • They are economically significant, used in industries such as construction, manufacturing, and transportation. 
  • Extraction involves mining and subsequent smelting or refining processes.
• Non-Metallic Minerals: While lacking metallic elements and luster, non-metallic minerals such as Quartz, Feldspar, Mica, Calcite, Talc, Gypsum, and Diamond find applications in construction, ceramics, glass-making, and more. 
  • These minerals are generally brittle, lack malleability and ductility, and have lower electrical and thermal conductivity. 
  • They are often widely distributed in various geological formations.

3. Based on Iron Content: Metallic minerals are classified into ferrous and non-ferrous minerals:

• Ferrous Minerals: Mainly constituted by iron, ferrous minerals like Iron ore (Hematite, Magnetite), Manganese, Chromium, and Nickel. 
  • They are crucial for industries like steel production. 
  • They exhibit magnetic properties, are strong and durable but susceptible to rusting and corrosion when exposed to moisture. 
• Non-Ferrous Minerals: Without iron as the main constituent, non-ferrous minerals like Copper, Lead, Zinc, Aluminum, Gold, Silver, and Tin find applications in various industries, including electrical, construction, and aerospace. 
  • Generally lacking magnetic properties, they vary in strength and hardness, and are resistant to rusting and corrosion.

4. Based on Origin: classified into organic and inorganic minerals:

• Organic: Derived from plant or animal organic materials; examples include coal, petroleum and peat; 
  • These are associated with fossilised organic remains.
• Inorganic: Formed through geological processes; examples include quartz, limestone, graphite, feldspar, gypsum, and mica; 
  • lack a biological origin.

Conclusion

Mineral classification aids in understanding their occurrence and economic significance. Major minerals, abundant in the Earth’s crust, contribute significantly to the economy, while minor minerals serve niche purposes. Understanding metallic and non-metallic minerals, along with their iron content, helps in industrial applications. Understanding these classifications helps in mining and using minerals wisely.