sedimentary
Septarian Nodule (Dragon Stone) sphere
Septarian concretion (Calcite, Aragonite, and Limestone)
Hardness: 3.5-4; Color: Yellow (Calcite), Brown (Aragonite), Grey (Limestone/Clay); Luster: Vitreous to dull; Crystal structure: Trigonal/Orthorhombic; Specific gravity: approx 2.7.
- Hardness
- 3
- Color
- Yellow (Calcite), Brown (Aragonite), Grey (Limestone/Clay)
- Luster
- Vitreous to dull
Identified More sedimentary →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 3.5-4; Color: Yellow (Calcite), Brown (Aragonite), Grey (Limestone/Clay); Luster: Vitreous to dull; Crystal structure: Trigonal/Orthorhombic; Specific gravity: approx 2.7.
Formation & geological history
Formed during the Cretaceous period (50-70 million years ago) in marine environments. Volcanic eruptions killed sea life which sank to the seafloor, forming mud balls. As the mud balls dried and shrank, they cracked, and minerals like Calcite and Aragonite drifted in to fill the voids.
Uses & applications
Primarily used for decorative purposes, ornamental carvings, lapidary spheres, and as a popular collector specimen for those interested in geology and metaphysics.
Geological facts
The word Septarian comes from the Latin word 'septum', meaning partition, referring to the cracks or separations within the rock. They are often called 'Dragon Stones' due to their scaly, cracked appearance that resembles mythical dragon eggs.
Field identification & locations
Identified by its distinctive three-color patterns showing yellow centers, brown borders, and grey outer shells. They are most famously found in Utah (USA) and Madagascar. To identify in the field, look for round, lumpy mudstone concretions that reveal crystalline interiors when cracked.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary
Sandstone (Quartz-rich)
Arenite (SiO2)
sedimentary
Sandstone (with man-made markings)
Arenite (composed primarily of Quartz, SiO2)
sedimentary