Apatite petrifactions in Pennsylvanian shales of Illinois

Abstract

ABSTRACT Phosphatic petrifactions of wood have been collected from two separate localities in the Pennsylvanian of Illinois. Optical microscopy, X-ray diffraction, and chemical analyses show that the mineralization is primarily carbonate fluorapatite. One petrifaction is closely associated with nodules and irregular masses of similar fluorapatite composition. The early replacement of wood by carbonate fluorapatite indicates the ready formation of the fluorapatite under some diagenetic conditions and suggests that the origin of at least some of the nodules and irregular masses is not necessarily from coprolites or other organic residues.