Een Pyriet-septarie uit het Oligoceen van Winterswijk

A concretion with a septarian core and a mantle of pyrite with calcareous clay is described. The pyrite occurs in cracks in the core, in crack-like fillings at the outer rim of the calcareous mass and in burrow holes in the outer part of the concretion. It is discussed that the nodule must have formed penecontemporaneously with the sedimentation and near a non-sequence.