sedimentary
Septarian Nodule (Dragon Stone)
Septarian Geode (CaCO3 + Mg + Fe)
Hardness: 3.5-4 (Mohs); Color: Gray (limestone), Yellow (calcite), Brown (aragonite); Luster: Waxy to vitreous; Structure: Trigonal/Hexagonal crystals within a concretion; Specific Gravity: 2.6-2.8
- Hardness
- 3
- Color
- Gray (limestone), Yellow (calcite), Brown (aragonite)
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 3.5-4 (Mohs); Color: Gray (limestone), Yellow (calcite), Brown (aragonite); Luster: Waxy to vitreous; Structure: Trigonal/Hexagonal crystals within a concretion; Specific Gravity: 2.6-2.8
Formation & geological history
Formed during the Cretaceous period (approx. 50-70 million years ago) specifically in ancient sea beds where mud and decomposing organic matter created nodules. As they dried and shrank, cracks formed and were filled with minerals like calcite and aragonite.
Uses & applications
Decorative items, lapidary carvings (points/spheres), metaphysical collecting, jewelry, and interior design showpieces.
Geological facts
The name 'Septarian' comes from the Latin word 'septum' meaning wall or partition, referring to the cracks that divide the nodule. They are colloquially known as Dragon Stones due to their scaly appearance.
Field identification & locations
Identify by the distinctive 'cracked' pattern (septaria) with yellow calcite centers and dark aragonite borders. Commonly found in Utah (USA) and Madagascar. Often found by looking for rounded, heavy concretions in shale deposits.
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