sedimentary

Septarian Nodule (Brown)

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

Hardness varies by mineral component (3.5 to 4 for calcite/aragonite, up to 4 for limestone); colors are typically brown, yellow, and white; vitreous to dull luster; amorphous to microcrystalline structure with distinct crystal-filled cracks (septaria); conchoidal fracture.

Identified July 28, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed in sedimentary environments approximately 50 to 100 million years ago (Cretaceous period). Mudballs or concretions dried and cracked internally, and mineral-rich groundwater subsequently deposited crystals (usually calcite or aragonite) into the resulting cavities.

Uses & applications

Popular as a decorative stone, carved into spheres or display pieces, collected by mineral enthusiasts, and used in metaphysical practices.

Geological facts

The word 'septarian' comes from the Latin word 'septem,' meaning seven, referring to the radiating cracks that often form in seven-pointed patterns. Each nodule is entirely unique.

Field identification & locations

Easily identified by its distinctive dark brown exterior combined with contrasting spider-web-like veins of lighter minerals (often white or yellow calcite/aragonite) running through it. Found worldwide, with notable deposits in Madagascar, Utah, and England.

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