Septarian Nodule (Dragon Stone)

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.

Identified on: 4/29/2026

Mode: Standard