sedimentary
Septarian Nodule (Dragon Stone)
Septarian concretion (primarily Calcite, Aragonite, and Limestone/Claystone mixture)
Hardness: 3.5-4; Color: Yellow (calcite), brown (aragonite), and grey (limestone); Luster: Waxy to vitreous; Crystal structure: Trigonal (calcite/aragonite centers); Specific gravity: ~2.60-2.70.
- Hardness
- 3
- Color
- Yellow (calcite), brown (aragonite), and grey (limestone)
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 3.5-4; Color: Yellow (calcite), brown (aragonite), and grey (limestone); Luster: Waxy to vitreous; Crystal structure: Trigonal (calcite/aragonite centers); Specific gravity: ~2.60-2.70.
Formation & geological history
Formed during the Cretaceous period (50-70 million years ago) through the desiccation and shrinkage of clay nodules in sea beds, followed by the cracking and subsequent filling of cracks with minerals like calcite and aragonite.
Uses & applications
Primarily used for decorative purposes, ornamental carvings, polished spheres, metaphysical practices (grounding), and as collector specimens.
Geological facts
The name comes from the Latin word 'septum', referring to the partitions or cracks within the stone. They are often called 'Dragon Stones' due to their scaly, cracked appearance that resembles mythical dragon skin.
Field identification & locations
Identify in the field by looking for rounded, dull-looking nodules in sedimentary layers; once cracked or cut, they reveal a unique angular 'star' pattern of veins. Common locations include Utah, USA, and Madagascar.
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