Are concretion rocks worth anything?

Generally, calcareous concretions are valued much like pearls. Brighter colors and stronger saturations command higher prices. Rounds and ovals are more desirable, and other shapes are judged based on how symmetrical they appear. Smoother surfaces, higher luster, and larger sizes also increase value.

What is a septarian concretion?

Septarian concretions (or septarian nodules) are carbonate-rich concretions containing angular cavities or cracks (septaria; sg. septarium, from the Latin septum “partition, separating element”, referring to the cracks or cavities separating polygonal blocks of hardened material).

Where can I find concretions?

Concretions are found in shale, occasionally in sandstone, and even in coal. If coal balls are described as concretions, coal may also be included. Concretions are most commonly composed of calcium carbonate or iron carbonate, although they may occur in sediments that are lacking in either carbonate.

Do all concretions contain fossils?

Concretions are commonly misunderstood geologic structures. Often mistaken for fossil eggs, turtle shells, or bones, they are actually not fossils at all but a common geologic phenomenon in almost all types of sedimentary rock, including sandstones, shales, siltstones, and limestones.

How do you identify concretions?

A concretion consists of the same material as the rock around it, plus the cementing mineral, whereas a nodule (like flint nodules in limestone) is composed of different material. Concretions can be shaped like cylinders, sheets, nearly perfect spheres, and everything in between. Most are spherical.

How are Septarian concretions formed?

Septarian nodules formed as a result of volcanic eruptions and compressed matter of Dead Sea creatures. Therefore, the bonds of Septarian nodules are formed in sediment through the “concretion” of mud masses and mixed organic material.

What does a concretion look like?

Although often rounded, concretions can be lumpy, long, oval, disk-shaped, or irregular. They vary in color, hardness, and size—from smaller than the head of a pin to several hundred pounds—and are sometimes misidentified as fossils, dinosaur eggs, or meteorites.