sedimentary

Septarian Nodule (Dragon Stone) sphere

Septarian concretion (Calcite, Aragonite, and Limestone)

AI-generated identification · may be incorrect

Hardness: 3.5-4; Color: Yellow (Calcite), Brown (Aragonite), Grey (Limestone/Clay); Luster: Vitreous to dull; Crystal structure: Trigonal/Orthorhombic; Specific gravity: approx 2.7.

Hardness: 3
Color: Yellow (Calcite), Brown (Aragonite), Grey (Limestone/Clay)
Luster: Vitreous to dull

Identified May 10, 2026More sedimentary →

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Physical properties

Hardness: 3.5-4; Color: Yellow (Calcite), Brown (Aragonite), Grey (Limestone/Clay); Luster: Vitreous to dull; Crystal structure: Trigonal/Orthorhombic; Specific gravity: approx 2.7.

Formation & geological history

Formed during the Cretaceous period (50-70 million years ago) in marine environments. Volcanic eruptions killed sea life which sank to the seafloor, forming mud balls. As the mud balls dried and shrank, they cracked, and minerals like Calcite and Aragonite drifted in to fill the voids.

Uses & applications

Primarily used for decorative purposes, ornamental carvings, lapidary spheres, and as a popular collector specimen for those interested in geology and metaphysics.

Geological facts

The word Septarian comes from the Latin word 'septum', meaning partition, referring to the cracks or separations within the rock. They are often called 'Dragon Stones' due to their scaly, cracked appearance that resembles mythical dragon eggs.

Field identification & locations

Identified by its distinctive three-color patterns showing yellow centers, brown borders, and grey outer shells. They are most famously found in Utah (USA) and Madagascar. To identify in the field, look for round, lumpy mudstone concretions that reveal crystalline interiors when cracked.