sedimentary

Septarian Nodule (Dragon Stone)

Calcite-Aragonite-Limestone Septarian

AI-generated identification · may be incorrect

Hardness: 3.5-4 (Mohs); Color: Yellow (calcite), brown (aragonite), grey (limestone); Luster: Vitreous to dull; Crystal structure: Trigonal/Orthorhombic; Specific gravity: 2.7-2.9

Hardness: 3
Color: Yellow (calcite), brown (aragonite), grey (limestone)
Luster: Vitreous to dull

Identified June 30, 2026More sedimentary →

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Physical properties

Hardness: 3.5-4 (Mohs); Color: Yellow (calcite), brown (aragonite), grey (limestone); Luster: Vitreous to dull; Crystal structure: Trigonal/Orthorhombic; Specific gravity: 2.7-2.9

Formation & geological history

Formed during the Cretaceous period (50-70 million years ago) when volcanic eruptions killed sea life that sank to the ocean floor. Decomposing matter attracted minerals that formed nodules; as the seabed dried and cracked, calcite and aragonite filled the cavities.

Uses & applications

Primarily used as decorative display specimens, for jewelry (mostly cabochons), and highly valued by metaphysical practitioners and rock collectors.

Geological facts

Septarian is often called 'Dragon Stone' because the internal pattern resembles dragon skin or scales. They are unique among concretions because of their distinctive shrinking cracks (septaria) filled with mineral precipitates.