This is a beautiful, polished Septarian nodule. It has been polished by hand to a very high standard from very good grade Septarian mined in Madagascar. It perfectly shows off the beautiful patterning that makes Septarian so special.
Septarian nodules formed 50 to 70 million years ago. As a result of volcanic eruptions, dead sea life was chemically attracted to the sediment around them, forming mud balls. As the ocean receded, the balls dried and cracked. They also shrank in size, creating the cracks inside. Decomposed shells seeped down into these cracks, forming Calcite crystals. The outer walls of the calcite then transformed into aragonite. Septarian nodules are composed of Calcite (The Yellow Centers), Aragonite (The Brown Lines), and the outer grey rock is Limestone.