Origin and Formation of the Hardest Rock on the Earth

Emma | 05 - 21 - 2021

Diamonds are the hardest known naturally formed rock on earth. Both Mohs’ scale and Vickers scale determined diamond as the hardest rock on earth. It is considered the hardest mineral because it is most difficult to cut or break.

Hardest Rock Origin

Diamond is said to have originated around 2500BC. It is believed that diamond got its name from the Greek word “Adamas,” meaning “unbreakable” or “unconquerable.” There are several mythological stories associated with diamonds’ origin, but people commonly believed that diamonds were something outside of the world. 

  • Ancient Greeks and Romans believed diamonds were a part of a falling star.
  • Some believed that it was the tears of god.
  • Many theories say it was from Cupid’s arrow.
  • Hindu mythology believed that diamond was formed after the lightning storm. 

Scientific studies say that diamonds are formed on the earth’s surface through four different processes. 

What Is the Hardness of Diamond on the Mohs Scale?
  • A. 7
  • B. 8
  • C. 9
  • D. 10
  1. Earth’s mantle– Mantle is one of the highest temperature places. Geologists say that diamonds are formed in the earth’s mantle and delivered to the surface by deep-source eruptions. The eruption produced kimberlite and lamproite pipes.
  2. Subduction zones– In this process, a diamond is formed when two tectonic plates collide, one settles down into the earth’s mantle. Carbon rocks from the surface are subjected to increasing heat of the mantle combined with the pressure from the colliding plates. This causes tiny diamonds to form in rocks. 
  3. Impact sites– Earth has been hit by many asteroids. When asteroids hit the earth, it collides with carbon rocks and produces pressure and heat. The high temperature and pressure cause diamond formation. Impact-site diamonds are not suitable for use because they are small and of low quality. 
  4. Space– NASA researchers and Smithsonian scientists have found a large number of nanodiamonds in meteorites. Scientists say that about three percent of the carbon in meteorites is contained in the form of nanodiamonds. It is also said that diamonds in meteorites cannot be used for industrial or commercial purposes. 

Is Diamond the Hardest Rock? 

Diamond is regarded as the hardest rock in the world, and it tops 10 on the Mohs scale. Diamond is so hard that it can cut anything. Nothing can cut or break diamonds but themselves. Diamonds used for cutting purposes are different from diamonds used for jewelry. Cutting diamonds are abundantly found on earth. A Decade back, scientists discovered two harder materials than diamond- wurtzite boron nitride and the mineral lonsdaleite. Both have a similar structure to diamond but consist of different atoms. 

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