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Hello all, 

I can’t figure this one out! I was collecting fossils from a highly yielding site in Peace River. In this little section of gravel that I reached, it was almost entirely fossilized bone from dugong and whale and turtle. Nestled in the center of this pile of fossils, I uncovered this stone and was immediately taken aback. I have been rock and fossil hunting my entire life, and extensively in this state and this river, and I have never seen anything like this. I have an enormous and worldly collection of rocks and fossils, and I have never seen something this smooth naturally. It is the smoothest stone I have ever seen. It is far too smooth to be riverworn. When I lived in TN I would find rocks that had been remarkably smoothed by the passing river water, but that is not the case with this rock, I am confident. It is soft and heavy and slippery. If I had seen it in a house I would have thought it had been professionally polished. It is not porous at all, it is not smoothed bone or a phosphate nodule. It is significantly heavy and deeply black, almost blue. It looks as though the color beneath the black exterior is almost a light greenish. Even the area where the green is showing through is completely soft. In the flash of my phone light the entire stone almost looks bluish green. The closest explanation I have reached is that it is either a burnishing stone used by Native Americans (I have found artifacts and bone tools nearby this site, so perhaps they smoothed the stone out while using it for processing hides, etc) or it is some sort of fossilized gizzard stone or gastrolith. I know this is unlikely, as we have no dinosaur fossils here, but I read somewhere that extinct whale remains have produced such fossils before, as they apparently utilized gizzard stones as well. If anyone could help me out, I would so appreciate it! Also I apologize for the photo quality and scale, I was trying to capture how different it is than bone and its unique colors. 








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some manganese concretions on pebbles or clay may have that appearance, but the manganese coating is not as soft as you describe.



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Wondering just how soft because gastroliths are hard, if it is soft it would be ground up in the stomach instead of doing the grinding I would think, same would be true for a tool it wouldn't hold up if it were soft.  I have seen very similar stones in creek I go to that are actually peices of hard clay or marl that is easily smoothed and rounded then covered with accumulated tannin, when wet in the right light the color of the clay kinda shows through. They also have that slick feel. Have no idea if that's what you have though.

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I'm afraid this will not be confirmed as either a gastrolith or artifact. There just aren't indications available.

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I think by soft you refer to its smooth silky surface, not to it being easily indented, for example with a fingernail?

it has a gastrolith look to it, and if found together with bones of gastrolith-using animals the chances are high. Hard to proof though.

I once found a similarly smooth stone near the vache noir rocks in France, which are famous for their pliosaur fossils. But museum staff that I asked told me only Sauropods had gastroliths and where not found there, which I believed back then, but which is of course wrong.


Best Regards,




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9 hours ago, Mtwombly said:

(...) It is significantly heavy and deeply black, (...)

I'd try to measure its density by immersion. A manganese or iron-oxide coat would make it highter than common rocks

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I see potential for this indeed being either a stone tool or gastrolith, as both can result in a smooth surface such as the one you describe and may, moreover, be made from non-local rock. Unfortunately, though, both these interpretations are highly context-sensitive, meaning a burnishing stone would need to be found along with an intact archaeological assemblage, whereas a gastrolith would need to be found in associated with undisturbed skeletal remains of an animal known to have used them. With the find location being a fluvial deposit, there's no context available. And while the item was found amidst a collection of bones, there's no way of telling whether these are associated as, given enough energy, a river will sort material of roughly the same weight together (and you did mention the piece is relatively heavy)... Similarly, fluvial action would also negate any potential informative value that may be otherwise be found in the rock having a foreign origin, as there's no way to tell how far the stone has been transported. And while a lot of animals did use gastroliths (including the aforementioned pl(es)iosaurs), the lack of association means the claim of this being a gastrolith cannot be substantiated. Very frustrating, I know, but that's how it is with these types of trace fossils.

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