This pteridophyte (fern) fossil was chipped out of a Western PA quarry. It's special in that it has a fossil impression on both the front and back sides. It is wrapped in solid tarnish resistant copper and hung it from a very soft cord of deerskin leather. It is part of Florida West's Jurassic Jewelry Collection.
Solid copper handmade clasp
Fossil pendant: 1 3/8" L x 7/8" W (35mm x 25mm)
Silver Pearlized Leather Cord - Adjustable up to 19 1/2"
Materials: 300 million yr old fossil from the Pennsylvanian Era of the Carboniferous Period, solid tarnish resistant copper, deerskin leather
Upper Pennsylvanian, Westphalian D to Stephanian A
Conemaugh Group: Glenshaw Formation: Mahoning Shale
Illustration of a Carboniferous Coal Forest
The Ambridge site and other nearby sites expose the remains of a Carboniferous Coal Forest. These remains are now fossilized in layers of shale from the Glenshaw Formation.
Pecopteris - Tree Fern
La terre avant le deluge, 1874, 7th edition. (Public Domain)
Seed Ferns, which are technically called (Peridospermatophyta), are often preserved as intricate carbon films and are prized by fossil plant collectors. The name comes from the fact that they had fern like foliage, but reproduced with seeds. Many seed ferns of the Carboniferous were tree like, while others were vine like. The tree forms did not have true trunks, but instead had a large trunk that was made from hundreds of tiny roots.
Two common seed ferns from the Pittsburgh area are Psaronius (Pecopteris) and Medullosa (Macroneuropteris).
Psaronius was a tree fern that grew up to 30 feet in height. The fern like fronds of Psaronius are composed of many small leaflets.
These plant fossils slabs were carbonized.
However, through complicated oxidation and replacement reactions, the Pyrite replaced the carbon and then a white substance called Pyrophyllite replaced the Pyrite. Now the fossils have a white film instead of a black carbon film.
Carbonization is the process where only the residual carbon of the organism remains. In nature this usually happens over time when the organism is subject to heat and pressure.
An... example of carbonization are fossil plants, where only a thin carbon layer is left on a piece of shale. (FossilGuy.com)