sedimentary
Septarian Nodule
Calcite-filled Concretion
AI-generated identification · may be incorrectHardness 3.5 to 4 on Mohs scale, brownish exterior with yellow calcite veins, dull to vitreous luster, amorphous to microcrystalline structure.
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Physical properties
Hardness 3.5 to 4 on Mohs scale, brownish exterior with yellow calcite veins, dull to vitreous luster, amorphous to microcrystalline structure.
Formation & geological history
Formed in sedimentary mudstone layers during the Cretaceous period through the drying and cracking of iron-rich concretions filled with mineral-rich groundwater.
Uses & applications
Used primarily in lapidary arts, decorative carvings, metaphysical crystal collecting, and polished display pieces.
Geological facts
Septarian nodules often form around a fossil nucleus and are frequently called dragon stones due to their scaly, patterned appearance.
Field identification & locations
Identified by distinctive radial cracks filled with contrasting yellow calcite or aragonite. Commonly found in Madagascar, Utah, and England.
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