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.