sedimentary

Septarian Nodule (Dragon Stone)

Septarian (composed of Calcite CaCO3, Aragonite CaCO3, and Limestone/Clay)

Hardness: 3.5-4.0 (Mohs scale); Color: Brown, tan, and yellow with grey exterior; Luster: Waxy to vitreous; Crystal Structure: Trigonal/Orthorhombic; Cleavage: Perfect rhombohedral in calcite portions; Specific Gravity: 2.7-2.9

Hardness: 3
Color: Brown, tan, and yellow with grey exterior
Luster: Waxy to vitreous

Identified March 31, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed as sedimentary concretions during the Cretaceous period (50-70 million years ago). They originated as mud balls that cracked as the ocean receded and the mud dried, with the cracks later being filled by calcite and aragonite minerals.

Uses & applications

Primarily used as decorative display specimens, for jewelry (cabochons), and in metaphysical collecting. Often polished into spheres, eggs, or used as bookends.

Geological facts

Known as 'Dragon Stones' because the crackled patterns resemble dragon skin. The name 'Septarian' comes from the Latin word 'septum', meaning partition, referring to the internal cracks that divide the stone's sections.

Field identification & locations

Identify by its unique 'turtle shell' or crackled pattern of yellow/white veins against a dark brown matrix. Most famously found in Utah (USA) and Madagascar. To identify in the field, look for round, lumpy grey nodules that look like clay balls.

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