Fern fossil, from Mason Creek, Illinois

&lt;p&gt;Classic specimen from the famous Mason Creek (Illinois) locality. &amp;nbsp;The fern fossils are found within concretions. &amp;nbsp;Apparently, ground water containing dissolved iron moved through buried Pennsylvanian strata, and the local presence of organic material caused progressive precipitation of iron oxides. &amp;nbsp;Concretions built up as a result. &amp;nbsp;Tapping the concretion with a hammer can cause the concretion to split right along the leaf. &amp;nbsp;Delicacy of preservation is amazing. &amp;nbsp;With a magnifying glass it is possible to see spores preserved on these leaves.&lt;/p&gt;

Whereabouts

Mason Creek locality to be sure, …but this specimen coming to me resulted from casual conversation with a fellow passenger on a flight back east in the mid-1980s. We got talking about geology, and it turns out he was a rock hound and had collection of Mason Creek specimens. He sent me this fossil a few weeks later! I love it. Who wouldn’t?

Age & Formation

Pennsylvanian, ~310 Ma.

QTVR

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