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No. 95: Sep-Oct 1994

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Might diamonds be dead bacteria?

How can something as beautiful, pure, and crystalline as a diamond be made from dead, disgusting bacteria? In truth, all diamonds are full of impurities and curious microscopic structures. (See: "Diamonds Are an Anomalist's Best Friend" in SF#92.)

The main constituent of diamonds is carbon, but even chemically pure carbon is contaminated in a sense. The contaminant is light carbon; that is, C12 , which is an isotope used preferentially by living organisms. Some diamonds, it is found, contain anomalously large fractions of C12, which suggests they have an organic origin. Some diamonds also contain sulfide inclusions that have sulphur-isotope ratios also symptomatic of a biological origin.

The specific diamonds suspected to have an organic origin are the so-called "eclogitic" diamonds. These diamonds may have obtained their carbon and impurities from bacterial communities that once lived around hydrothermal vents that existed along ancient mid-ocean ridges. Subsequent metamorphism (heat and pressure) turned the masses of bacteria into eclogitic diamonds. So, those sparklers of yours may just be clumps of billion-year-old bacterial corpses!

(Nisbet, E.G., et al; "Can Diamonds Be Dead Bacteria?" Nature, 367:694, 1994.)

Definition. Eclogites comprise a class of metamorphic rocks formed at extremely high temperatures and pressures.

From Science Frontiers #95, SEP-OCT 1994. 1994-2000 William R. Corliss

Science Frontiers Sourcebook Project Reviewed in:


  • "A sourcebook of unexplained phenomena is therefore a valuable addition to a collection of scientific literature. William R. Corliss has provided this in the past with his source books of scientific anomalies in several subjects, and now he has provided it for astronomy. He has done an excellent job of collecting and editing a large amount of material, taken in part from scientific journals and in part from scientific reporting in the popular or semi-scientific press." -- "The Mysterious Universe: A Handbook of Astronomical Anomalies", reviwed by Thomas Gold, Cornell University, in Icarus, vol.41, 1980

  • "An interesting, systematic presentation of unusual weather [..] This book is recommended for a general audience" --"Corliss, William R., Tornados, Dark Days, Anomalous Precipitation, and Related Weather Phenomena, Sourcebook Project, 1983.", revieweed in Choice, September 1983
  • "..the science is necessarily somewhat speculative, but Corliss's symthesis is based on reputable sources." -- "Corliss, William R. (Compiler). Lightning, Auroras, Nocturnal Lights, and Related Luminous Phenomena" reviwed by Joseph M. Moran, Univ. of Wisconsin in Science Books and Films, Sep/Oct 1983

  • "Before opening the book, I set certain standards that a volume which treads into dangerous grounds grounds like this must meet. The author scrupulously met, or even exceeded those standards. Each phenomenon is exhaustively documented, with references to scientific journals [..] and extensive quotations" -- "Book Review: The moon and planets: a catalog of astronomical anomalies", The Sourcebook Project, 1985., Corliss, W. R., Journal of the Royal Astronomical Society of Canada, Vol. 81, no. 1 (1987), p. 24., 02/1987