4" Wide Fossil Horsetail (Sphenophyllum?) Plate - Pennsylvania

This is a plate of shale featuring a herbaceous horsetail (Sphenophyllum sp.?) fossil from the Pennsylvanian aged (305 million year) Llewellyn formation of Pennsylvania. These plants were buried in a swamp where a low temperature, pressure, and oxygen environment the plant tissue was slowly replaced by pyrite. This pyrite was later replaced by a whitish mineral (aluminum silicate) as the fossils were buried and exposed to the heat and pressure inside of the earth.

It comes with an acrylic display stand.