sedimentary
Septarian Nodule
Septarian Concretion (Calcite, Aragonite, and Limestone)
AI-generated identification · may be incorrectHardness of 3-4 on the Mohs scale, brownish-grey exterior with yellow calcite veins, dull to vitreous luster, amorphous nodular structure with conchoidal fracture.
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Physical properties
Hardness of 3-4 on the Mohs scale, brownish-grey exterior with yellow calcite veins, dull to vitreous luster, amorphous nodular structure with conchoidal fracture.
Formation & geological history
Formed during the Cretaceous period approximately 50 to 100 million years ago when mud-rich sediments accumulated and shrank, creating shrinkage cracks that filled with mineral-rich water precipitating calcite and aragonite.
Uses & applications
Popularly used for lapidary work, carved into decorative objects, and collected as display specimens.
Geological facts
The name originates from the Latin septum, meaning partition, referring to the radiating cracks that divide the nodule into distinctive patterns.
Field identification & locations
Easily identified by its turtle-shell-like exterior and internal network of crystalline veins, commonly found in marine sedimentary layers worldwide.
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