The listing, Polished Septarian Nodule- Unique Specimen! has ended.
Great sample of a septarian nodule. I found, cut and polished this unique creation of nature from Utah. It has yellow to opaque white calcite crystals (to 3mm) in veins/cracks, contrasted nicely to the dark gray mudstone matrix. The backside (not pictured) is the smooth, raw texture of the stone. This is a concretion (check wikipedia) formed in the mud of the ancient ocean that covered a great portion of the US about 75 million years ago! Even looks like a Native American lizard petroglyph!