Diamond

• Diamond is the hardest naturally occurring substance found on Earth and has been the most valuable gem for more than 2,000 years.
• It occurs in two types of deposits: igneous rocks of basic or ultrabasic composition and alluvial deposits derived from the primary sources.
• Diamonds are formed in the mantle and brought to the earth’s crust through volcanism. They are composed of pure carbon and have a cubic crystal system with a common form of octahedron.
• India is known for its diamond cutting and polishing business, especially for small-sized diamonds. The Indian diamond industry handles about 80% of the global polished diamond market, with Surat in Gujarat being a major center for the industry.
• Diamonds are not only used for jewelry but also as an industrial material due to their hardness. They are used for making grinding, drilling, cutting, and polishing tools.
• Diamond exhibits high thermal conductivity and electrical resistivity, making it suitable for applications in semiconductors.

Diamond Distribution in India

• Diamond occurrences reported in India since prehistoric times
• Diamond fields of India grouped into four regions:
  • South Indian tract of Andhra Pradesh
    • Comprises parts of Anantapur, Kadapa, Guntur, Krishna, Mahabubnagar, and Kurnool districts
  • Central Indian tract of Madhya Pradesh
    • Comprising Panna belt
  • Behradin-Kodawali area in Raipur district and Tokapal, Dugapal, etc. areas in Bastar district of Chhattisgarh
  • Eastern Indian tract mostly of Odisha
    • Lying between Mahanadi and Godavari valleys

• Reserves estimated only in Panna belt and Krishna Gravels in Andhra Pradesh
• New kimberlite fields discovered in Raichur-Gulbarga districts of Karnataka
• Madhya Pradesh accounts for about 90.18% of resources
• Andhra Pradesh accounts for 5.72% of resources
• Chhattisgarh accounts for 4.09% of resources
• Only one mine in India located in Majhgaon, Panna (Madhya Pradesh) operated by NMDC
• Mine has a production capacity of 84,000 carats
• Total diamonds recovered from this mine so far are little more than 1 million carats

Graphite

• Graphite is a naturally occurring form of crystalline carbon, also known as plumbago or black lead or mineral carbon.
• It is a stable form of naturally occurring carbon with a carbon content of never less than 95%.
• Graphite is not normally used as fuel because it is difficult to ignite and may be considered the highest grade of coal, just above anthracite.
• It is found in metamorphic and igneous rocks, and most of it is formed at convergent plate boundaries where organic-rich shales and limestones were subjected to metamorphism due to heat and pressure.
• Metamorphism produces marble, schist, and gneiss that contain tiny crystals and flakes of graphite.
• Some graphite forms from the metamorphism of coal seams, known as “amorphous graphite”.
• Graphite is extremely soft, cleaves with very light pressure, and is extremely resistant to heat and highly unreactive.
• It is a non-metal and the only non-metal that can conduct electricity.

Applications of Graphite

• Natural graphite is used for refractories, batteries, steelmaking, expanded graphite, lubricants, etc.
• Refractory materials retain their strength at high temperatures.
• Natural and synthetic graphite are used to make the anode of all major battery technologies.
• Lithium-ion batteries use roughly twice as much graphite as lithium carbonate.
• Natural graphite is used in carbon raising in molten steel to make steel stronger.
• Natural amorphous graphite is used in brake linings for heavier vehicles.
• Graphite lubricants are used at very high or very low temperatures.
• Modern pencil lead is typically made from a mix of powdered graphite and clay.

Indian Graphite Resources

• India’s Graphite occurrences are found in states like Jammu and Kashmir, Gujarat, Jharkhand, Arunachal Pradesh, Karnataka, Kerala, Maharashtra, Tamil Nadu, Odisha, Chattisgarh, and Rajasthan.  
• As per GSI’s 2013 report,
  • Arunachal Pradesh (43%),
  • Jammu & Kashmir (37%),
  • Jharkhand (6%),
  • Tamil Nadu (5%) and
  • Odisha (3%)
• Operational Indian Graphite Resources
  • Most of the Graphite Production is concentrated in these states
  • Tamil Nadu (37%),
  • Jharkhand (30%), [Palamu district in Jharkhand is the most important]
  • Odisha (29%).
• Active mining centres of graphite are in
  • Jharkhand – Latehar & Palamu districts
  • Odisha – Bargarh, Nuapada, Rayagada & Balangir districts
  • Tamil Nadu – Madurai & Sivagangai districts

Differences Between Graphite and Diamond

Diamond	Graphite
In diamonds, strong three-dimensional networks are formed due to the presence of covalent bonds.	Graphites are formed due to the weak van der Waals force of attraction.
Hard in nature	Soft in nature.
Since molecules are closely packed they have high density.	Because of the large gap between the molecules, they have low density.
Since there is no free carbon atom, the diamond does not conduct electricity.	Because of the presence of free carbon atoms in graphite, they can conduct electricity.
Diamond is 100% carbon.	Graphite contains 95% or more carbon.
Diamond (one of the most stable) is less stable than graphite.	Graphite is one of the most stable substances on earth.