sedimentary

Septarian Nodule

Septarian Concretion (Calcite, Aragonite, Limestone, and Barite)

AI-generated identification · may be incorrect

Hardness of 3.5 to 4 on the Mohs scale, brownish-yellow exterior with dark gray centers, dull to vitreous luster, amorphous to cryptocrystalline structure with radial shrinkage cracks.

Identified November 12, 2026More sedimentary →

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Physical properties

Hardness of 3.5 to 4 on the Mohs scale, brownish-yellow exterior with dark gray centers, dull to vitreous luster, amorphous to cryptocrystalline structure with radial shrinkage cracks.

Formation & geological history

Formed in marine sediments during the Cretaceous period approximately 50 to 100 million years ago through the dehydration and cracking of iron-rich mud nodules, which were later filled with mineral precipitation.

Uses & applications

Used primarily as decorative lapidary objects, polished display specimens, spheres, and in metaphysical healing practices.

Geological facts

The word septarian comes from the Latin septem, meaning seven, referring to the radiating pattern of cracks that typically divide the concretion into seven or more segments.

Field identification & locations

Easily identified by its distinctive turtle-back surface texture and internal spiderweb pattern of yellow calcite veins; found globally in marine shale and limestone deposits.