Mystery shape found in Pennsylvanian shale -- Identified
Middle Pennsylvanian Series
Desmoinesian Stage - Marmaton Group
Altamont Formation - Lake Neosho Shale Member
St. Louis, Missouri
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Beekite ring: Collected and photograph by Scott Schaefer
A friend found this interesting shape while sifting the shale.
This looks more like a specimen of a cryptocrystalline quarts mineral called Beekite.
We commonly find it here in Nebraska, especially on shells of productoid and atrypoid
brachiopods and on some crinoid cups. Sometimes we find loose examples as your
specimen. Loope and Watkins in the paper listed below described this phenomenon
and related it to Pennsylvanian fossils from Utah and Nebraska. As a quick test, if you
rub it across a piece of glass, it will scratch the glass if it is beekite. A drop of vinegar
would produce a fizzy if it is carbonate, but be sure any residual carbonate is gone.
Loope, D. B., and Watkins, D. K., 1989, Pennsylvanian fossils replaced by red chert:
early oxidation of pyritic precursors: Journal of Sedimentary Petrology, v. 59, no. 3,
In my original post I wrote that the shape was familiar, however, I couldn't remember
why or where. Now I remember ... I never found or collected these Beekite rings
separately. I remember seeing these rings on badly weathered Mississippian corals
(and probably other fossils). The reason I couldn't remember (why or where) was
because I was focused on the individual specimen and not the coiled rope-like features
that sometimes are noticed on some fossils.
See Bill Rushlau's page: Beekite rings on brachiopods
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