This pteridophyte (fern) fossil was found in a Western PA quarry.  It is wrapped it in solid tarnish resistant copper and hung it from a very soft necklace of deerskin leather.  It is part of Florida West's Jurassic Jewelry Collection.

Fossil Size:  2 1/2"L x 1 5/8"W (65mm x 40mm)

Overall Pendant Size: 3 3/4"L x 1 5/8"W (102mm x 40mm)

Black Deerskin Leather Cord - 29" L

Clasp:  Handmade Tarnish Resistant Solid Copper

Materials:  300 million yr old fossil from the Pennsylvanian Era of the Carboniferous Period, solid tarnish resistant copper, deerskin leather

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.

Description

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 (Pecopteris) 
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.

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)