sedimentary
Septarian Nodule
Septarian concretion (Calcite, Aragonite, Limestone)
AI-generated identification · may be incorrectHardness ranges from 3 to 4 on the Mohs scale depending on the mineral present. Displays brownish-grey exterior with contrasting yellow calcite or brown aragonite veins.
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Physical properties
Hardness ranges from 3 to 4 on the Mohs scale depending on the mineral present. Displays brownish-grey exterior with contrasting yellow calcite or brown aragonite veins.
Formation & geological history
Formed from ancient muddy sediments during the Cretaceous period, developing shrinkage cracks that later filled with mineral-rich groundwater.
Uses & applications
Polished into decorative display pieces, bookends, and spheres for mineral collectors and home decor.
Geological facts
The name originates from the Latin word septum, meaning partition, referring to the distinctive cracks that divide the nodule into sections.
Field identification & locations
Easily identified in the field by its rounded, potato-like exterior and internal network of radiating cracks filled with crystalline minerals.
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