A meticulously chosen septarian sphere from our collection of crystals, rocks and minerals. This highly polished sphere boasts beautiful calcite crystals within a contrasting border of aragonite.
Septarian was formed during the Cretaceous Period the end of which was marked by the extinction of the dinosaurs. It's a very distinctive stone that's more correctly known as a septarian nodule or concretion because in geology, that's a more accurate description of what it actually is. Made up of yellow calcite, brown aragonite and limestone, septarian is a unique combination of rock, mineral and organic matter.
It's not known exactly how septarian nodules were formed but it's believed that the shells of dead and decaying sea life attracted sediment and minerals to accumulate around them and in doing so, nodules or mud balls were created. As the oceans receded the nodules dried out and slowly cracked due to shrinkage in the clay. Natural minerals subsequently flowed through what was now sedimentary rock filling the cracks and causing the formation of yellow calcite crystals.
This septarian sphere is a beautiful and eye catching piece that would make a lovely gift for anyone with an interest in geology and polished minerals.
Weight (grams): 190
Size (cms): 4.9 in diameter