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Excerpt from section 2 of the exhibition
FROM THE DEPTHS OF THE EARTH
INTRA- AND EXTRATERRESTRIAL DIAMONDS
Our understanding of the processes involved in the formation of diamond continues to evolve. In recent decades, scientists have found diamonds that crystallized in three conditions of hitherto unsuspected ultrahigh pressure.
- The collision of slow-moving continental plates may subject parts of the crust to immense burial and uplift – with diamonds forming in the buried crust.*
- A meteor impact, a heavenly body that has fallen to Earth, produces immense heat and pressure in which diamond may be formed and then sprayed amongst the impact debris. Colliding meteorites may also produce diamonds.**
- Lastly, the remnants of very old meteorites contain microscopic diamonds formed, it is believed, during the death of stars.***
* In Kazahkstan (Russia), such diamonds returned to the surface after the host rock was pushed over 120 km deep into the Earth! A revolutionary discovery - such burial of the crust had never been seen before. (diagram)
** At the Popigai crater (Siberia), formed by a meteor impact 35 million years ago, graphite transformed into diamond aggregates up to one centimeter across! It is now suspected that diamonds form in most major impacts and might be an new indicator of ancient cosmic collisions, such as are believed to have led to the extinction of dinosaurs.
*** In 1987, such microscopic crystals were recovered from meteorites that predate the solar system! Recent studies indicate that these nanodiamonds formed more than five billion years ago from carbon-rich gas and flashes of radiation from dying giant stars. The process is essentially the same as the new method for growing synthetic diamond called chemical vapor deposition.
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