sedimentary

Septarian (Dragon Stone)

Septarian Concretion (SiO2 + CaCO3)

AI-generated identification · may be incorrect

Hardness: 3.5-4 (Mohs scale); Color: Yellow (calcite), brown (aragonite), gray (limestone); Luster: Earthy to vitreous; Crystal structure: Trigonal/Orthorhombic components.

Hardness: 3
Color: Yellow (calcite), brown (aragonite), gray (limestone)
Luster: Earthy to vitreous

Identified May 31, 2026More sedimentary →

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Physical properties

Hardness: 3.5-4 (Mohs scale); Color: Yellow (calcite), brown (aragonite), gray (limestone); Luster: Earthy to vitreous; Crystal structure: Trigonal/Orthorhombic components.

Formation & geological history

Formed roughly 50 to 70 million years ago during the Cretaceous period from the solidification of mud pools as sea levels receded, creating shrinkage cracks that later filled with minerals.

Uses & applications

Primarily used for ornamental carvings, pocket stones, decorative pyramids/points, and jewelry. Highly valued by collectors for its unique 'cracked' aesthetic.

Geological facts

The name comes from the Latin word 'septum', meaning partition, referring to the cracks that divide the concretion. Their patterns are unique like fingerprints.

Field identification & locations

Identified by high-contrast yellow calcite filled cracks within a darker earthy matrix. Commonly found in Utah, USA and Madagascar. Collectors should look for vibrant crystallization in the 'veins'.