| Fossils from St. Clair, PA |
| All plant fossils here were found in the Llewellyn Formation (300 mya, Pennsylvanian Period) and are one of the few places where one can find these very detailed white (sometimes yellow) ferns on a striking contrast of black shale. The plants died and fell into the swamp, where in a low temperature, pressure, and oxygen environment the plant tissue was slowly replaced by pyrite (from sulphides). Pyrophyllite (aluminum silicate, a whitish mineral) is believed to have replaced the pyrite at a later stage as the sediments piled up and the temperature and pressure became greater. The ferns most commonly found are Alethopteris, Neuropteris, Pecopteris, and Sphenophyllum.
Click the photo to enlarge.
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Photos from the Rutgers Geology Museum:
1) Alethopteris - Seed Fern, 2) Neuropteris - Seed Fern, 3) Sphenophyllum, 4) Sphenopteris - Seed Fern, 5) Stigmaria - Either Lepidodendron or Sigillaria, 6) Cyclopteria - Neuropteris type Seed Fern
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From e-bay:
14 inch long slab
1 foot long slab
1 foot long slab
2 foot by 2 foot slab
16 inch long slab
15 inch long slab
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