Fern Fossil

Fern Fossil plates from St. Clair, PA. For sale as pictured.

These plant fossils occur in black shale matrix, and have a characteristic white coating of the mineral pyrophyllite

The Llewellyn Formation: (Info from: Fossilguy)
This is a Pennsylvanian age formation (precisely 300 to 308 myo) that contain sequences of Sandstone, Siltstone, Shale, Conglomerate, and Anthracite Coal (according to the USGS). Each layer represents a different depositional environment. In particular, the shale was probably formed from sedimentation of a muddy bottomed coastal lagoon. During storms, plant material in the coastal bogs (which were abundant during this time period) washed offshore into the lagoon. Many of these plant fragments settled onto the low oxygen muddy bottom and were covered by a rain of fine black sediment. The ferns became fossilized in the black shale layers.

Collected in: St. Clair, PA