Septarian nodules form when cracks in sedimentary concretions are later filled by minerals such as calcite or quartz. They may form as muddy sediment dries, shrinks, and cracks, allowing mineral-rich water to flow into the openings.
Septarian Nodule
Rocks I've Found on the Beach
Septarian nodules form when cracks in sedimentary concretions are later filled by minerals such as calcite or quartz. They may form as muddy sediment dries, shrinks, and cracks, allowing mineral-rich water to flow into the openings.