Polished Septarian from Utah
These septarian nodules have been polished to a vitreous lustre.
Septarian is an interesting material composed of yellow calcite and aragonite, within a limestone or mudstone matrix.
It's relatively soft, so must be handled carefully
Septarian nodules formed in marine sediments during the Jurassic to Cretaceous periods, roughly 200 to 66 million years ago. They formed as mineral-rich sediment slowly hardened and cemented into a nodule over several million years.
Details
1. 96.2g | 5.3 x 4.5 x 3cm - £14.50
2. 60.1g | 4.6 x 2cm - £9.25
3. 31.5g | 4 x 3 x 1.9cm - £5.25