Where is Septarian Nodule found?
Septarian Nodule (calcite, aragonite, and limestone/shale)
Got a photo? Identify rocks instantly with the Rockby app
Open the appSeptarian Nodule occurs in specific geological environments. Knowing where to look, and in what kind of rock, is the difference between going home empty-handed and finding a great specimen.
Where to find Septarian Nodule
Madagascar
Known for producing large, high-quality septarian nodules with excellent calcite infillings, often exhibiting a striking yellow-brown color.
Utah, USA
Specifically the 'Dragon Egg' nodules from the Morrison Formation, characterized by their distinctive patterns and often containing barite in addition to calcite.
New Zealand
Found in various sedimentary formations, often with well-defined septaria.
England
Occurrences in Jurassic and Cretaceous sedimentary rocks, particularly in coastal areas.
Canada
Found in sedimentary basins, often associated with shale and mudstone deposits.
Collecting tips
- Look for Concretions. Septarian nodules often appear as rounded or oval-shaped concretions in exposed sedimentary rock layers, particularly in shales, mudstones, and limestones. Look for areas where erosion has exposed these layers.
- Check for Cracks. While the exterior may look like a plain rock, a key indicator is the presence of subtle cracks or a slightly irregular surface that might hint at the internal septaria. Sometimes, small pieces of the infilling minerals might be visible on the surface.
- Break Open Carefully. To confirm identification, a nodule may need to be carefully broken open. Look for the characteristic internal network of cracks filled with contrasting minerals (typically yellow/brown calcite) against the darker host rock.
- Coastal and Riverbed Environments. Erosion in coastal cliffs, riverbeds, and badlands can expose septarian nodules that have weathered out of their host rock. They may be found as loose specimens.
Quick Check
- Color:
- Dark grey/brown exterior, yellow/brown/white interior cracks.
- Luster:
- Dull exterior, vitreous interior crystals.
- Streak:
- White (for calcite/aragonite components).
Explore Septarian Nodule
Identify rocks anywhere
Free on iOS, Android, and Web. Photo identification, full database, and your personal collection.