septarium

An irregular polygonal system of calcite-filled cracks occurring in certain rock concretions.

A concretion or nodule of considerable size, and roughly spherical in shape, of which the parts nearest the center have become cracked during the drying of the mass, the open spaces thus formed having been subsequently filled with some infiltrated mineral, usually calcite. Such septaria or septarian nodules are abundant in various shaly rocks, especially in the Liassic beds in England.

A flattened concretionary nodule, usually of limestone, intersected within by cracks which are often filled with calcite, barite, or other minerals.

A flattened concretionary nodule, usually of limestone, intersected within by cracks which are often filled with calcite, barite, or other minerals.