Abstract
The Leicester marcasite bed (Devonian), N.Y., the Clinton ironstone (Silurian), N.Y., and Wabana pyrite beds (Ordovician), Newfoundland, show varying degrees of early diagenetic, pseudomorphous pyritization and marcasitization of fossils and hematite-chamosite oolites. The fossils are replaced by either a mixture of framboidal and microgranular sulfides, or by microgranular or fibrous sulfides alone, but the oolites are replaced by structureless pyrite and fibrous marcasite, never by framboidal pyrite. The pyritized material occurs with other pyrite and lesser quantities of marcasite in concentric and radial concretions, crystal aggregates, framboids, framboidal clusters, and other spherical structures, all considered to be of early diagenetic age.
