4.4" Polished Septarian Egg with Stand - Madagascar

This is a beautiful, hand-polished egg and stand that were both sculpted from septarian. The septarian comes from the Betsiboka Region of Madagascar and was deposited during the Jurassic period. The polishing reveals a beautiful pattern of yellow calcite, brown aragonite, and grey-brown limestone. The polished septarian base has a concave depression that the egg sits upright within, creating this aesthetic display.

The egg itself is 4.4" tall and including the stand the entire specimen is 5.25" tall.

Septarian or septarian nodules are concretions containing angular cavities or cracks, called "septaria", filled with calcite and aragonite. A concretion is a hard, compact mass of rock that often forms around decaying organic matter. In the case of septarian nodules, the concretions formed around decaying sea-life in a marine environment.

The exact mechanism for how the cracks form in the concretions is a mystery. One possible mechanism is the dehydration of the clay-rich core of a concretion, causing it to shrink and crack. The cracks could also be caused by gas expansion produced by the decaying organic matter within a concretion. Earthquakes have also been suggested as yet another mechanism.

The cracks in the concretions are then filled in with minerals such as calcite (yellow), aragonite (brown), and sometimes pyrite, causing the very interesting patterns. They have often been described as looking like dragon's skin. They are frequently found as geodes with hollow, calcite crystal-filled cavities. More rarely, the fossils that originally started the formation of the concretion are still preserved in the septarian.
FOR SALE
$49 $41
DETAILS
SPECIES
Septarian
LOCATION
Ambondromamy, Betsiboka Region, Madagascar
SIZE
Egg: 4.4 x 3.05"
CATEGORY
ITEM
#252826