Septarian Nodule Slice
Stunning septarian nodule slice measuring approx 4.5" x .25"
Utah Septarians are found in Southern Utah, about 15 miles from Zion National Park. Septarians were formed sometime during the Cretaceous Period, also known as the age of dinosaurs, between 144 to 65 million years ago. During this period of time what is now known as the Gulf of Mexico extended into present day Utah, forming a vast interior sea. On this ancient seabed decomposing sea life, killed by volcanic eruptions, had a chemical attraction for the sediment around them and became trapped. Along with tide and wave actions, mud balls of sediment were formed on the sea floor. The waters receded leaving the mud balls to dry out and crack. Because of the bentonite content, the mud balls also shrank trapping the cracks inside. The ocean returned for a period depositing more sediment and sea life on top. As the sea life decomposed, the calcite from the shells seeped into the cracks forming calcite crystals. A thin wall of calcite was transformed into aragonite which divides the heavy bentonite clay exteriors from the calcite centers. Septarians received their name because of this aragonite division. (Septum is Latin for division). Some Septarian centers filled completely with calcite and are called nodules. Other more rare Septarians are hollow and are called geodes.
Septarians are very desirable because of their contrasting colors, unique patterns and their stunning calcite crystals. Since fossils started the formation of the rock, they are often found in the Septarian, making it even more unique.
Septarians are sedimentary rocks that lie in a three foot layer of clay sediment which is usually found 40 - 50 feet beneath the earth's surface. Because of the depth, heavy mining equipment is needed to peel back the layers of time covering these gems of the ancient sea. Septarians are found in a variety of sizes. Once the Septarians are out of the ground, they are taken to a lapidary shop that specializes in bringing out the natural beauty of the rock through cutting, grinding and polishing.
COMPOSITION: Calcite (the yellow centers) Aragonite (the brown lines)
Limestone (the outer grey rock which is the bentonite clay replaced with limestone)