sedimentary
Septarian Nodule
Septarian Concretion (Calcite, Aragonite, Limestone, and Barite)
AI-generated identification · may be incorrectHardness of 3-4 on the Mohs scale. Displays brown carbonate mudstone exterior with yellow calcite or aragonite veining.
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Physical properties
Hardness of 3-4 on the Mohs scale. Displays brown carbonate mudstone exterior with yellow calcite or aragonite veining.
Formation & geological history
Formed 50 to 100 million years ago during the Cretaceous period when mud nodules cracked due to shrinking and were filled with mineral-rich groundwater.
Uses & applications
Popular as a decorative display specimen, for carving into ornamental objects, and prized by fossil and mineral collectors.
Geological facts
The name comes from the Latin word septum, meaning partition, referring to the distinctive network of cracks inside.
Field identification & locations
Easily identified by its turtle-shell-like pattern of intersecting mineral veins. Commonly found in Madagascar, Utah, and the UK.
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