Carboniferous Period, 359-259 million years B.P. A bifacial white Pecopteris sp. fern specimen in an irregular matrix. 1.2 kg, 21.5 cm (8 1/2 in.). St. Clair, Pennsylvania, USA. Acquired 1980s. Pradi collection, Boston, USA. These fern fossils are verymon from coal mining areas around the world. However, it is the unique state of preservation of the white on the black shale that gives the St. Clair ferns their beauty and rarity. [No Reserve]