sedimentary
Septarian Nodule
Septarian Concretion
AI-generated identification · may be incorrectHardness 3.5 to 4 on the Mohs scale, featuring brown, yellow, and grey colors with a dull to vitreous luster and a microcrystalline structure.
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Physical properties
Hardness 3.5 to 4 on the Mohs scale, featuring brown, yellow, and grey colors with a dull to vitreous luster and a microcrystalline structure.
Formation & geological history
Formed around 50 to 100 million years ago during the Cretaceous period through the drying and cracking of mud concretions, with the resulting cavities later filled with minerals like calcite.
Uses & applications
Used primarily in decorative carvings, tumbled stones, jewelry making, and as a popular display specimen for mineral collectors.
Geological facts
The name septarian comes from the Latin word septum, meaning partition, referring to the radiating cracks that form the distinctive pattern inside the nodule.
Field identification & locations
Easily identified in the field by its distinct turtle-back or cracked mud pattern outlined with contrasting mineral veins; commonly found in sedimentary layers in Utah, Madagascar, and England.
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