Opalized Fossil

When an opalized fossil has a beautiful gem color, is it worth cutting?
Let’s evaluate this Skin Shell opalized fossil I have to see if it’s worth keeping as a fossil or turning it into a gem.

Ancient Inland Sea

Where all the opal fields lie throughout Australia is actually along the edges of an ancient inland sea.
These include:
– Lightning Ridge
– Andamooka
– Coober Pedy
– Mintabie
– Lambina
– White Cliffs
– Cunnamulla
– Koroit
– Junda
– Eromanga
– Quilpie
– Opalton
– Winton

Image courtesy of InColor Magazine

How does an opalized fossil form?

Most of the fossils found in these areas are either crustaceans, shellfish, or animals that lived in or around the water’s edge that have been buried through sediment.
The organic matter or shell breaks down and leaves a cavity where the animal matter was.
The sediments that buried animal remains in the opal fields were rich in silica from ancient volcanoes, the silica spheres seep down into the cavity to fill it and the fossils are preserved as silica in the form of opal.
Some examples are Shells, Yabby Buttons, Pipi’s/Molluscs , and Turtle Bones which have turned into opal.

Should I cut this Opalized Fossil?

When an opal fossil has a beautiful gem color, is it worth cutting it and turning it from a fossil into a gem because the color is so incredible?
Sometimes it can be worth cutting, unless you’re a Paleontologist you may not agree with cutting a 110 million-year-old fossil.
Fossils can be very valuable but so can opal gems.
This particular opalized fossil is a Skin Shell from Coober Pedy and they are quite common, so I am happy to cut this one.

Final Result

The whole process was quite relaxing and an easy cut and polish.
We finished with a gorgeous 3.32ct Baroque Shape White Opal.
I paid around $500 for it as a fossil and have valued it at $1200 as a gem opal which you can find it here.

12 thoughts on “Opalized Fossil”

  1. Beautiful colour in that piece of shell Justin. It amazing what natural World and process’s can produce. Not being wealthy I have bought bottles of colour chips and pieces that often have shell pieces in them. Being thin pieces I make doublets out of them. I am not in it for the money but to add to my collection and highlight the colour in thinner pieces.
    I love getting them out on a sunny day and looking at the colours. and patterns. Not worth much money but to me they are treasures!! A few little solids among them but dull compared the flashy stones you cut. Love opal

  2. Absolutely beautiful, love it great job. Your amazing,watch every video you post. One day I’ll buy one of your works of art. Thankyou

  3. My thoughts would that if the fossil had any significance from a paleontology point of view one would cut and shape accordingly. Most pieces of shell opal that I have finished are so bright and gorgeous, I find they satiate the opal addiction for that moment. If you personified black opal with the Mona Lisa , shell opal is like a gorgeous girl wearing a stunning floral print on a perfect day. Who would want to deprive the world of such pleasure. I think that in the sentiment of history, man’s desire will always win. To my mind it is a great question and puts equal responsibility on being a custodian and an artisan.

  4. Always interesting, love that you share different points of view. I am curious why a gem over 3 carats, with such bright colors (including
    red), is valued at $1200.00? Still a lot of money, but it was a stunner!!

    Thanks for any info and sharing your knowledge

  5. If the fossil is a rare specimen important for the natural history, it must of course be in a museum, where it can be admired for two reasons, both beauty and biology 🙂
    If quite common, it is okay to polish it and sell it.

  6. I Justin
    I am going to sell my opalised Dinosaur or Pterosaur bones ?
    Would you be interested to buy it
    They are still partially in the sandstone , with a tooth that I removed.
    If you want to see some pictures
    Google opalised pterosaur tibia / Fibula my name is Andre Stucki


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