English Name：Black Diamond, Carbonado
Chemical Composition：C (Carbon with minor impurities)
Crystal System：Cubic (Black Diamond: Single Crystal or Carbonado: Polycrystalline)
Locality：Single Crystal(Black Diamond): South Africa, Australia,
Canada, Russia, Namibia, India
Polycrystalline (Carbonado): Brazil, Central African Republic
Age：Carbonado: 2.6 - 3.8 billion years old
Remarks：Black Diamonds: single crystal (lots of graphite inclusions)
Carbonado, came from outer space, geologists have discovered. (Credit: Florida International University)
Sources of Carbonado Diamonds: its origin remains debatable
1. Metamorphism caused by a meteoric impact on the earth's crust during the Precambrian era.
2. The transformation of organic sedimentary carbon into diamond in a cold subducted slab.
3. Radiation-induced diamond formation from organic carbon
Carbonado diamonds are geologically very old: 2.6 to 3.8 billion years old.
Carbonado is only found in central South Africa and Brazil. It has been identified as containing hydrogen, which means that it was created in a hydrogen-based environment like interstellar space.
It is possible that a diamond meteorite struck the Earth at that time, accounting for carbonado’s current distribution.
Researchers Jozsef Garai and Stephen Haggerty have argued that the diamonds in carbonado may have been formed in supernovae explosions, which sent chunks of the material into space and ultimately on a collision course with Earth. The impact of these asteroid-sized diamond bodies with the unique geology and oxygen-poor atmosphere of the Earth 2.6 to 3.8 billion years ago may have formed the polycrystalline material we now call carbonado “black diamonds.”