sedimentary
Septarian Nodule
Septarian Concretion
AI-generated identification · may be incorrectHardness 3-4 on Mohs scale, brownish-red exterior with yellow calcite or grey limestone fracture fillings, dull to earthy luster, massive crystal structure.
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Physical properties
Hardness 3-4 on Mohs scale, brownish-red exterior with yellow calcite or grey limestone fracture fillings, dull to earthy luster, massive crystal structure.
Formation & geological history
Formed in sedimentary mudstone layers during the Cretaceous period through the drying and cracking of iron-rich concretion mudballs, later filled with mineral-rich water.
Uses & applications
Popular in ornamental carving, polished display pieces, sphere-making, and metaphysical collecting.
Geological facts
The name originates from the Latin word septum, meaning partition, referring to the distinctive network of shrinkage cracks inside.
Field identification & locations
Easily identified by its turtle-shell or geometric polygonal cracking pattern on a rounded nodule; commonly found in Madagascar, Utah, and England.
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