matte SEPTARIA sphere with lid – Madagascar –

This sphere of SEPTARIA, originally from Madagascar, has been partially polished to accentuate its spherical shape. Then it was cleverly broken, exactly along a slit, to reveal a cavity lined with crystallizations. A small brass button has been added to the upper part, allowing thel lid to be lifted and the inside to be discovered. The pale outer stone contrasts strikingly with the dark calcite inside.
Septaria forms in clay-rich sediments that shrink as they dry, creating cracks later filled by minerals. These internal patterns, known as septa (from the Latin septum, meaning partition), are the result of a slow geological process involving pressure, mineral-rich water, and microbial activity.
A striking curiosity specimen, mounted on a brass base.