sedimentary
Septarian Nodule
Septarian Concretion (Calcite, Aragonite, Limestone, and Barite)
AI-generated identification · may be incorrectHardness ranges from 3 to 4 on the Mohs scale due to calcite and aragonite. Colors are typically brown, yellow, and grey with intersecting network veins.
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Physical properties
Hardness ranges from 3 to 4 on the Mohs scale due to calcite and aragonite. Colors are typically brown, yellow, and grey with intersecting network veins.
Formation & geological history
Formed in sedimentary mudstone layers during the Cretaceous period roughly 50 to 100 million years ago through the desiccation and shrinkage of mud concretions.
Uses & applications
Commonly used for ornamental carvings, polished display specimens, spheres, and lapidary art. Valued by mineral collectors worldwide.
Geological facts
The name originates from the Latin word septum, meaning partition, referring to the characteristic cavity-filling cracks called septa.
Field identification & locations
Easily identified by its distinctive turtle-shell-like pattern of brownish mudstone divided by yellow calcite veins. Frequently found in marine sedimentary clay deposits.
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