4.2" Wide Fossil Horsetail (Sphenophyllum) Plate - Pennsylvania

This is a plate of fossil herbaceous horsetail (Sphenophyllum sp.) whorls from the Pennsylvanian aged (305 million year) Llewellyn formation of Pennsylvania. The white color of these detailed fossils contrasts well against the black shale they are preserved in. 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.