sedimentary
Septarian Nodule
Septarian Concretion (Calcite, Aragonite, and Limestone)
AI-generated identification · may be incorrectHardness of 3.5-4 on Mohs scale, brownish-grey color with yellow calcite veins, dull to vitreous luster, amorphous concretionary structure.
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Physical properties
Hardness of 3.5-4 on Mohs scale, brownish-grey color with yellow calcite veins, dull to vitreous luster, amorphous concretionary structure.
Formation & geological history
Formed in sedimentary mud/shale layers during the Cretaceous period through the drying and cracking of concretions filled with mineral-rich water.
Uses & applications
Used widely in decorative carvings, polished palm stones, spheres, and as a popular collectible specimen.
Geological facts
Septarian nodules are often called dragon stones due to their reptilian pattern of intersecting cracks filled with golden calcite.
Field identification & locations
Easily identified by their distinctive turtle-shell pattern of internal veins; found prominently in Madagascar and Utah.
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