A very precious fossil

From ZME Science via reader Ant, we have a priceless and amazing fossil.  The description:

Yes, what you are looking at is a natural, though extremely rare phenomenon – quite possibly unique in the world. This fossilised gastropod from the Colombian mine of Gachala has been completely replaced by precious emerald.
Formed from hydrothermal fluids in a shear zone interacting with the rock they passed through, the fossil in the host black shale was transformed. If you look carefully you can also see many small crystals of pyrite, a common inclusion in emeralds from this country. Despite its small size (1.3×1.1×0.9Cm), the preservation is near perfect. This fossil is, as far as I know, unique.



  1. Marella
    Posted July 4, 2013 at 4:07 am | Permalink

    Wow! Never heard of that before. There’s a lot of fossils replaced by opal but emerald is amazing!

  2. Alex Shuffell
    Posted July 4, 2013 at 4:10 am | Permalink

    Wow! I didn’t even know something like that was possible. There was a taxi driver from Torquay (where I live) who got himself mummified after he died, that was my plan too. I think I want to be fossilised now.

    • Michael Fisher
      Posted July 4, 2013 at 6:12 am | Permalink

      Watery Fowls…

      • Alex Shuffell
        Posted July 4, 2013 at 7:11 am | Permalink

        Flowery Twats?

      • Michael Fisher
        Posted July 4, 2013 at 9:38 am | Permalink

        I felt obliged to go for the family-friendly faux-anagram… 🙂

    • Posted July 4, 2013 at 2:52 pm | Permalink

      Full fathom five thy father lies;
      Of his bones are coral made;
      Those are pearls that were his eyes:
      Nothing of him that doth fade,
      But doth suffer a sea-change
      Into something rich and strange.
      Sea-nymphs hourly ring his knell:
      (voices:) Ding-dong.
      Hark! now I hear them — Ding-dong, bell.

      – The Tempest

  3. Posted July 4, 2013 at 4:40 am | Permalink

    Nature = poetry in motion.

  4. Posted July 4, 2013 at 4:43 am | Permalink


  5. jesperbothpedersen1
    Posted July 4, 2013 at 4:44 am | Permalink

    Beautiful remains of a little snail.

  6. Ross Burnett
    Posted July 4, 2013 at 5:07 am | Permalink

    Wow. Before reading I was thinking coprolite.

  7. Posted July 4, 2013 at 5:27 am | Permalink

    How much is it worth?

  8. Posted July 4, 2013 at 6:00 am | Permalink

    All fossils are all precious.
    The Center For Inquiry Indiana recently had its annual Science Day for Children. Among other projects, the kids dug and chipped for fossils that we embedded in a plaster-like substance. There were plenty of gastropods and the kids learned to identify and age about a dozen different fossils. I told them the next time a Creationist friend told them the earth was less than 10 thousand years old, they could show proof that it was much older. Last year our CFI kids pasted feathers onto large wall chart pictures of “birds to be” dinosaurs. Our CFI kids are smart.

    • Mark Joseph
      Posted July 4, 2013 at 7:08 am | Permalink

      Hi Craig:

      Sounds cool. What kind of pushback do you get from the rabid right and other creationists in Indiana?

  9. Hempenstein
    Posted July 4, 2013 at 6:10 am | Permalink

    Did the emeralds form in situ, or did they wash into the shell and form a concretion (if that’s the right term) with pyrite once in there?

    OK, now I’ll go look at ZME Science and see if I can find out.

    • Hempenstein
      Posted July 4, 2013 at 6:26 am | Permalink

      The ZME page didn’t answer the question. And possible caveat: clicking SOURCE there takes me to a Facebook(!) page that has some further links that I didn’t follow.

    • Posted July 4, 2013 at 6:54 am | Permalink

      It’s hard to tell from the photo, but the fossil appears to be a steinkern, which is a solid cast of the fossil, rather than a replacement of the original shell material which would preserve the hollow spiral shape). My guess is that the snail shell was replaced and perhaps filled in with calcite and/or pyrite which are both common fossil-forming minerals. (The rock is a black shale so the snail may not even have been living in the mud, but might have washed in during a storm etc.) When the hot fluids entered the rock, emerald crystals formed in veins and cavities; the fluids might have partly dissolved the mineralized snail and replaced it with emerald crystals (and a lot of pore space, apparently). I’m not sure whether the pyrite is also recrystallized or whether it’s left over from an earlier generation of mineralization, but the photo suggests that at least some of it is recrystallized as isolated perfectly-formed crystals among the emeralds.

  10. Mark Joseph
    Posted July 4, 2013 at 7:14 am | Permalink


    Not only for its intrinsic interest, but as an example of a thoroughly natural process. Imagine a creationist trying to explain this in any manner than an arbitrary “(my) god did this.”

    • jesperbothpedersen1
      Posted July 4, 2013 at 7:53 am | Permalink

      It’s gawds way of testing the faith of his believers.

      • Mark Joseph
        Posted July 4, 2013 at 9:26 am | Permalink

        Yeah, he’s kind of a shit that way. Of course, if you fail the test, he tortures you forever, exactly the way any good father would respond to a lapse in conduct by his children.

  11. Posted July 4, 2013 at 7:46 am | Permalink

    I wonder: might this process be replicable by humans in commercial, rather than geologic, timescales?

    There’s the boundless aesthetic possibilities, of course…but I’m also now wondering about manufacturing processes, as an alternative to 3-D printing….


    • Posted July 4, 2013 at 9:23 am | Permalink

      I don’t see why not. I work in fine jewelry, and although we don’t do a lot of business in lab-grown gems, the process is fairly easy and common now. If you make some sort of matrix for the crystals to adhere to, it would be pretty simple, unless I’m misunderstanding your question.

      • Posted July 4, 2013 at 10:25 am | Permalink

        I guess I’m asking two different but related questions.

        Could you go down to the beach, pick up a pretty shell, and use an accelerated version of the same process that turned this shell into emerald to turn your beach shell into emerald?

        Also, could you manufacture a complex structure out of some easy-to-work-with substance and use a similar process to “fossilize” it into a hard-to-work-with substance? I’m thinking of something like a 3-D printer to create the structure, and then “fossilize” it into some form of beryl or other interesting mineral?


  12. lanceleuven
    Posted July 4, 2013 at 7:51 am | Permalink

    Wow, what a spectacular find. Amazing.

  13. Posted July 4, 2013 at 8:06 am | Permalink

    I’m envisioning a movie pitch. Indiana Jones and the Emerald… Snail? Nah. Indiana Jones and the Emerald Shell, that works!

    • Reginald Selkirk
      Posted July 4, 2013 at 11:03 am | Permalink

      That’s clearly not a snail shell, it’s an alien skull.

  14. Posted July 4, 2013 at 8:23 am | Permalink

    I had a delivery person at my office in Newfoundland several years ago. After dropping off the package, he paused at the office door to view a shelf of fossils and bones I always had on display. He seemed to really like the piece of unmineralised wood from one of the fossil forests in the High Arctic of Canada, so I told him that it was 46 million years old. He turned to me and said “you know the devil put it there”.

    It was quite a revelation to me!

  15. Posted July 4, 2013 at 9:23 am | Permalink

    That’s just incredible. Thank you for sharing.

  16. Reginald Selkirk
    Posted July 4, 2013 at 11:02 am | Permalink

    I have a liking for gold bug trilobite fossils with pyrite substitution, but pyrite (fool’s gold) isn’t actually worth much.

    • Posted July 4, 2013 at 2:58 pm | Permalink

      Mr Pyrites

      In posture and gesture he is suave and cool
      as the sodomist in charge of a Sunday school.

      He clings like a limpet,
      he sings like a trumpet,
      his manners are nice
      and his heart is blue ice.

      He loves like a ferret
      and speaks like a parrot,
      his navel is full
      of the rubbings of wool.

      He lisps like a neuter,
      sips ale from his pewter,
      and treads down the street
      like a tabby on heat.

      On tiptoe at Easter
      he crows like a rooster,
      then falls on his knees
      to his God and gives praise.

      He’s yes to his betters,
      duress to his debtors,
      white smiles are his eyes
      and his oaths are all lies.

      On Doomsday the angels will lift up their nighties
      and wipe away tears for Mr Pyrites.

      – A. R. D. Fairburn

      (nighties = nightgowns)

  17. Posted July 4, 2013 at 11:27 am | Permalink

    Wow,I wonder who keeps it?

  18. Posted July 5, 2013 at 2:09 am | Permalink

    According to one of the commenters on the source (a facebook page) wrote:
    ” Seems to be common for gastropods.

    • Mark Joseph
      Posted July 5, 2013 at 8:22 am | Permalink

      From the link you supplied:
      “According to geologists familiar with the Colombian mining region, the existance of these emerald gastropods clearly establishes the low temperature mineralization of the Colombian emerald. This is consistant with some of the newer theories of Colombian emerald mineralization as opposed to the high temperature metamorphic formation of most other emerald localities.”

      What, you mean the emerald gastropods weren’t formed in the same universal flood that hydrodynamically sorted all the animals and turned them into a perfect chronological-seeming fossil record, at the same time that it produced all the coal and oil? Who knew?

      I’m no mineralogist, but I’m going to go out on a limb and hazard the opinion that the mineralization process from shell to emerald takes something in excess of 6,000 years, and hence that these objects are older than the universe!

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